From ef44006ef67f59ff3a31b5c1d2fcd7f978bae77b Mon Sep 17 00:00:00 2001 From: Wilson Lin Date: Mon, 24 Aug 2020 23:59:19 +1000 Subject: [PATCH] Fix ECMA-262 bench page --- bench/tests/ECMA-262 | 8872 +++++++++++++++++++++--------------------- 1 file changed, 4436 insertions(+), 4436 deletions(-) diff --git a/bench/tests/ECMA-262 b/bench/tests/ECMA-262 index 31097fd..dbe7255 100644 --- a/bench/tests/ECMA-262 +++ b/bench/tests/ECMA-262 @@ -1,4 +1,4 @@ - + @@ -57,8 +57,8 @@

 

Contributing to this Specification

-

This specification is developed on GitHub with the help of the -ECMAScript community. There are a number of ways to contribute to the +

This specification is developed on GitHub with the help of the +ECMAScript community. There are a number of ways to contribute to the development of this specification:

Introduction

-

This Ecma Standard defines the ECMAScript 2019 Language. It is the -tenth edition of the ECMAScript Language Specification. Since +

This Ecma Standard defines the ECMAScript 2019 Language. It is the +tenth edition of the ECMAScript Language Specification. Since publication of the first edition in 1997, ECMAScript has grown to be one - of the world's most widely used general-purpose programming languages. -It is best known as the language embedded in web browsers but has also + of the world's most widely used general-purpose programming languages. +It is best known as the language embedded in web browsers but has also been widely adopted for server and embedded applications.

-

ECMAScript is based on several originating technologies, the most -well-known being JavaScript (Netscape) and JScript (Microsoft). The -language was invented by Brendan Eich at Netscape and first appeared in -that company's Navigator 2.0 browser. It has appeared in all subsequent -browsers from Netscape and in all browsers from Microsoft starting with +

ECMAScript is based on several originating technologies, the most +well-known being JavaScript (Netscape) and JScript (Microsoft). The +language was invented by Brendan Eich at Netscape and first appeared in +that company's Navigator 2.0 browser. It has appeared in all subsequent +browsers from Netscape and in all browsers from Microsoft starting with Internet Explorer 3.0.

The development of the ECMAScript Language Specification started in - November 1996. The first edition of this Ecma Standard was adopted by + November 1996. The first edition of this Ecma Standard was adopted by the Ecma General Assembly of June 1997.

-

That Ecma Standard was submitted to ISO/IEC JTC 1 for adoption -under the fast-track procedure, and approved as international standard -ISO/IEC 16262, in April 1998. The Ecma General Assembly of June 1998 -approved the second edition of ECMA-262 to keep it fully aligned with -ISO/IEC 16262. Changes between the first and the second edition are +

That Ecma Standard was submitted to ISO/IEC JTC 1 for adoption +under the fast-track procedure, and approved as international standard +ISO/IEC 16262, in April 1998. The Ecma General Assembly of June 1998 +approved the second edition of ECMA-262 to keep it fully aligned with +ISO/IEC 16262. Changes between the first and the second edition are editorial in nature.

-

The third edition of the Standard introduced powerful regular -expressions, better string handling, new control statements, try/catch +

The third edition of the Standard introduced powerful regular +expressions, better string handling, new control statements, try/catch exception handling, tighter definition of errors, formatting for numeric output and minor changes in anticipation of future language growth. The - third edition of the ECMAScript standard was adopted by the Ecma + third edition of the ECMAScript standard was adopted by the Ecma General Assembly of December 1999 and published as ISO/IEC 16262:2002 in June 2002.

After publication of the third edition, ECMAScript achieved massive adoption in conjunction with the World Wide Web where it has become the programming language that is supported by essentially all web browsers. - Significant work was done to develop a fourth edition of ECMAScript. -However, that work was not completed and not published as the fourth -edition of ECMAScript but some of it was incorporated into the + Significant work was done to develop a fourth edition of ECMAScript. +However, that work was not completed and not published as the fourth +edition of ECMAScript but some of it was incorporated into the development of the sixth edition.

The fifth edition of ECMAScript (published as ECMA-262 5th - edition) codified de facto interpretations of the language -specification that have become common among browser implementations and + edition) codified de facto interpretations of the language +specification that have become common among browser implementations and added support for new features that had emerged since the publication of - the third edition. Such features include accessor properties, -reflective creation and inspection of objects, program control of -property attributes, additional array manipulation functions, support -for the JSON object encoding format, and a strict mode that provides -enhanced error checking and program security. The fifth edition was + the third edition. Such features include accessor properties, +reflective creation and inspection of objects, program control of +property attributes, additional array manipulation functions, support +for the JSON object encoding format, and a strict mode that provides +enhanced error checking and program security. The fifth edition was adopted by the Ecma General Assembly of December 2009.

The fifth edition was submitted to ISO/IEC JTC 1 for adoption under - the fast-track procedure, and approved as international standard -ISO/IEC 16262:2011. Edition 5.1 of the ECMAScript Standard incorporated -minor corrections and is the same text as ISO/IEC 16262:2011. The 5.1 + the fast-track procedure, and approved as international standard +ISO/IEC 16262:2011. Edition 5.1 of the ECMAScript Standard incorporated +minor corrections and is the same text as ISO/IEC 16262:2011. The 5.1 Edition was adopted by the Ecma General Assembly of June 2011.

-

Focused development of the sixth edition started in 2009, as the -fifth edition was being prepared for publication. However, this was -preceded by significant experimentation and language enhancement design -efforts dating to the publication of the third edition in 1999. In a -very real sense, the completion of the sixth edition is the culmination +

Focused development of the sixth edition started in 2009, as the +fifth edition was being prepared for publication. However, this was +preceded by significant experimentation and language enhancement design +efforts dating to the publication of the third edition in 1999. In a +very real sense, the completion of the sixth edition is the culmination of a fifteen year effort. The goals for this addition included providing better support for large applications, library creation, and for use of - ECMAScript as a compilation target for other languages. Some of its -major enhancements included modules, class declarations, lexical block -scoping, iterators and generators, promises for asynchronous -programming, destructuring patterns, and proper tail calls. The -ECMAScript library of built-ins was expanded to support additional data -abstractions including maps, sets, and arrays of binary numeric values -as well as additional support for Unicode supplemental characters in + ECMAScript as a compilation target for other languages. Some of its +major enhancements included modules, class declarations, lexical block +scoping, iterators and generators, promises for asynchronous +programming, destructuring patterns, and proper tail calls. The +ECMAScript library of built-ins was expanded to support additional data +abstractions including maps, sets, and arrays of binary numeric values +as well as additional support for Unicode supplemental characters in strings and regular expressions. The built-ins were also made extensible via subclassing. The sixth edition provides the foundation for regular, - incremental language and library enhancements. The sixth edition was + incremental language and library enhancements. The sixth edition was adopted by the General Assembly of June 2015.

-

ECMAScript 2016 was the first ECMAScript edition released under -Ecma TC39's new yearly release cadence and open development process. A -plain-text source document was built from the ECMAScript 2015 source -document to serve as the base for further development entirely on -GitHub. Over the year of this standard's development, hundreds of pull -requests and issues were filed representing thousands of bug fixes, -editorial fixes and other improvements. Additionally, numerous software -tools were developed to aid in this effort including Ecmarkup, -Ecmarkdown, and Grammarkdown. ES2016 also included support for a new +

ECMAScript 2016 was the first ECMAScript edition released under +Ecma TC39's new yearly release cadence and open development process. A +plain-text source document was built from the ECMAScript 2015 source +document to serve as the base for further development entirely on +GitHub. Over the year of this standard's development, hundreds of pull +requests and issues were filed representing thousands of bug fixes, +editorial fixes and other improvements. Additionally, numerous software +tools were developed to aid in this effort including Ecmarkup, +Ecmarkdown, and Grammarkdown. ES2016 also included support for a new exponentiation operator and adds a new method to Array.prototype called includes.

-

ECMAScript 2017 introduced Async Functions, Shared Memory, and +

ECMAScript 2017 introduced Async Functions, Shared Memory, and Atomics along with smaller language and library enhancements, bug fixes, - and editorial updates. Async functions improve the asynchronous -programming experience by providing syntax for promise-returning + and editorial updates. Async functions improve the asynchronous +programming experience by providing syntax for promise-returning functions. Shared Memory and Atomics introduce a new memory model that allows multi-agent - programs to communicate using atomic operations that ensure a -well-defined execution order even on parallel CPUs. This specification + programs to communicate using atomic operations that ensure a +well-defined execution order even on parallel CPUs. This specification also includes new static methods on Object: Object.values, Object.entries, and Object.getOwnPropertyDescriptors.

-

ECMAScript 2018 introduced support for asynchronous iteration via -the AsyncIterator protocol and async generators. It also included four -new regular expression features: the dotAll flag, named capture groups, +

ECMAScript 2018 introduced support for asynchronous iteration via +the AsyncIterator protocol and async generators. It also included four +new regular expression features: the dotAll flag, named capture groups, Unicode property escapes, and look-behind assertions. Lastly it included rest parameter and spread operator support for object properties.

This specification, the 10th edition, introduces a few new built-in functions: flat and flatMap on Array.prototype for flattening arrays, Object.fromEntries for directly turning the return value of Object.entries into a new Object, and trimStart and trimEnd on String.prototype as better-named alternatives to the widely implemented but non-standard String.prototype.trimLeft and trimRight built-ins. In addition, this specification includes a few minor updates to syntax and semantics. Updated syntax includes optional catch binding - parameters and allowing U+2028 (LINE SEPARATOR) and U+2029 (PARAGRAPH -SEPARATOR) in string literals to align with JSON. Other updates include + parameters and allowing U+2028 (LINE SEPARATOR) and U+2029 (PARAGRAPH +SEPARATOR) in string literals to align with JSON. Other updates include requiring that Array.prototype.sort be a stable sort, requiring that JSON.stringify return well-formed UTF-8 regardless of input, and clarifying Function.prototype.toString by requiring that it either return the corresponding original source text or a standard placeholder.

-

Dozens of individuals representing many organizations have made -very significant contributions within Ecma TC39 to the development of +

Dozens of individuals representing many organizations have made +very significant contributions within Ecma TC39 to the development of this edition and to the prior editions. In addition, a vibrant community - has emerged supporting TC39's ECMAScript efforts. This community has -reviewed numerous drafts, filed thousands of bug reports, performed -implementation experiments, contributed test suites, and educated the -world-wide developer community about ECMAScript. Unfortunately, it is + has emerged supporting TC39's ECMAScript efforts. This community has +reviewed numerous drafts, filed thousands of bug reports, performed +implementation experiments, contributed test suites, and educated the +world-wide developer community about ECMAScript. Unfortunately, it is impossible to identify and acknowledge every person and organization who has contributed to this effort.

Allen Wirfs-Brock
ECMA-262, Project Editor, 6th Edition - +

Brian Terlson
ECMA-262, Project Editor, 7th through 10th Editions - +

@@ -210,48 +210,48 @@ impossible to identify and acknowledge every person and organization who

2Conformance

-

A conforming implementation of ECMAScript must provide and support -all the types, values, objects, properties, functions, and program +

A conforming implementation of ECMAScript must provide and support +all the types, values, objects, properties, functions, and program syntax and semantics described in this specification.

-

A conforming implementation of ECMAScript must interpret source -text input in conformance with the latest version of the Unicode +

A conforming implementation of ECMAScript must interpret source +text input in conformance with the latest version of the Unicode Standard and ISO/IEC 10646.

-

A conforming implementation of ECMAScript that provides an +

A conforming implementation of ECMAScript that provides an application programming interface (API) that supports programs that need - to adapt to the linguistic and cultural conventions used by different -human languages and countries must implement the interface defined by -the most recent edition of ECMA-402 that is compatible with this + to adapt to the linguistic and cultural conventions used by different +human languages and countries must implement the interface defined by +the most recent edition of ECMA-402 that is compatible with this specification.

-

A conforming implementation of ECMAScript may provide additional +

A conforming implementation of ECMAScript may provide additional types, values, objects, properties, and functions beyond those described - in this specification. In particular, a conforming implementation of -ECMAScript may provide properties not described in this specification, -and values for those properties, for objects that are described in this + in this specification. In particular, a conforming implementation of +ECMAScript may provide properties not described in this specification, +and values for those properties, for objects that are described in this specification.

-

A conforming implementation of ECMAScript may support program and -regular expression syntax not described in this specification. In -particular, a conforming implementation of ECMAScript may support -program syntax that makes use of the “future reserved words” listed in +

A conforming implementation of ECMAScript may support program and +regular expression syntax not described in this specification. In +particular, a conforming implementation of ECMAScript may support +program syntax that makes use of the “future reserved words” listed in subclause 11.6.2.2 of this specification.

-

A conforming implementation of ECMAScript must not implement any +

A conforming implementation of ECMAScript must not implement any extension that is listed as a Forbidden Extension in subclause 16.2.

3Normative References

-

The following referenced documents are indispensable for the -application of this document. For dated references, only the edition -cited applies. For undated references, the latest edition of the +

The following referenced documents are indispensable for the +application of this document. For dated references, only the edition +cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO/IEC 10646 Information Technology – Universal Multiple-Octet - Coded Character Set (UCS) plus Amendment 1:2005, Amendment 2:2006, + Coded Character Set (UCS) plus Amendment 1:2005, Amendment 2:2006, Amendment 3:2008, and Amendment 4:2008, plus additional amendments and corrigenda, or successor

ECMA-402, ECMAScript 2015 Internationalization API Specification. - +
https://ecma-international.org/publications/standards/Ecma-402.htm

ECMA-404, The JSON Data Interchange Format. - +
https://ecma-international.org/publications/standards/Ecma-404.htm

 @@ -259,41 +259,41 @@ Amendment 3:2008, and Amendment 4:2008, plus additional amendments and corri

4Overview

This section contains a non-normative overview of the ECMAScript language.

-

ECMAScript is an object-oriented programming language for -performing computations and manipulating computational objects within a -host environment. ECMAScript as defined here is not intended to be +

ECMAScript is an object-oriented programming language for +performing computations and manipulating computational objects within a +host environment. ECMAScript as defined here is not intended to be computationally self-sufficient; indeed, there are no provisions in this specification for input of external data or output of computed results. - Instead, it is expected that the computational environment of an -ECMAScript program will provide not only the objects and other -facilities described in this specification but also certain + Instead, it is expected that the computational environment of an +ECMAScript program will provide not only the objects and other +facilities described in this specification but also certain environment-specific objects, whose description and behaviour are beyond - the scope of this specification except to indicate that they may -provide certain properties that can be accessed and certain functions + the scope of this specification except to indicate that they may +provide certain properties that can be accessed and certain functions that can be called from an ECMAScript program.

-

ECMAScript was originally designed to be used as a scripting -language, but has become widely used as a general-purpose programming -language. A scripting language is a programming language that -is used to manipulate, customize, and automate the facilities of an -existing system. In such systems, useful functionality is already -available through a user interface, and the scripting language is a -mechanism for exposing that functionality to program control. In this -way, the existing system is said to provide a host environment of -objects and facilities, which completes the capabilities of the -scripting language. A scripting language is intended for use by both +

ECMAScript was originally designed to be used as a scripting +language, but has become widely used as a general-purpose programming +language. A scripting language is a programming language that +is used to manipulate, customize, and automate the facilities of an +existing system. In such systems, useful functionality is already +available through a user interface, and the scripting language is a +mechanism for exposing that functionality to program control. In this +way, the existing system is said to provide a host environment of +objects and facilities, which completes the capabilities of the +scripting language. A scripting language is intended for use by both professional and non-professional programmers.

ECMAScript was originally designed to be a Web scripting language, - providing a mechanism to enliven Web pages in browsers and to perform -server computation as part of a Web-based client-server architecture. -ECMAScript is now used to provide core scripting capabilities for a -variety of host environments. Therefore the core language is specified + providing a mechanism to enliven Web pages in browsers and to perform +server computation as part of a Web-based client-server architecture. +ECMAScript is now used to provide core scripting capabilities for a +variety of host environments. Therefore the core language is specified in this document apart from any particular host environment.

-

ECMAScript usage has moved beyond simple scripting and it is now -used for the full spectrum of programming tasks in many different +

ECMAScript usage has moved beyond simple scripting and it is now +used for the full spectrum of programming tasks in many different environments and scales. As the usage of ECMAScript has expanded, so has - the features and facilities it provides. ECMAScript is now a fully + the features and facilities it provides. ECMAScript is now a fully featured general-purpose programming language.

-

Some of the facilities of ECMAScript are similar to those used in +

Some of the facilities of ECMAScript are similar to those used in other programming languages; in particular C, Java™, Self, and Scheme as described in:

ISO/IEC 9899:1996, Programming Languages – C.

@@ -303,21 +303,21 @@ other programming languages; in particular C, Java™, Self, and Scheme as

4.1Web Scripting

-

A web browser provides an ECMAScript host environment for -client-side computation including, for instance, objects that represent -windows, menus, pop-ups, dialog boxes, text areas, anchors, frames, -history, cookies, and input/output. Further, the host environment -provides a means to attach scripting code to events such as change of -focus, page and image loading, unloading, error and abort, selection, -form submission, and mouse actions. Scripting code appears within the -HTML and the displayed page is a combination of user interface elements -and fixed and computed text and images. The scripting code is reactive +

A web browser provides an ECMAScript host environment for +client-side computation including, for instance, objects that represent +windows, menus, pop-ups, dialog boxes, text areas, anchors, frames, +history, cookies, and input/output. Further, the host environment +provides a means to attach scripting code to events such as change of +focus, page and image loading, unloading, error and abort, selection, +form submission, and mouse actions. Scripting code appears within the +HTML and the displayed page is a combination of user interface elements +and fixed and computed text and images. The scripting code is reactive to user interaction, and there is no need for a main program.

-

A web server provides a different host environment for -server-side computation including objects representing requests, -clients, and files; and mechanisms to lock and share data. By using -browser-side and server-side scripting together, it is possible to -distribute computation between the client and server while providing a +

A web server provides a different host environment for +server-side computation including objects representing requests, +clients, and files; and mechanisms to lock and share data. By using +browser-side and server-side scripting together, it is possible to +distribute computation between the client and server while providing a customized user interface for a Web-based application.

Each Web browser and server that supports ECMAScript supplies its own host environment, completing the ECMAScript execution environment.

@@ -326,108 +326,108 @@ customized user interface for a Web-based application.

4.2ECMAScript Overview

The following is an informal overview of ECMAScript—not all parts - of the language are described. This overview is not part of the + of the language are described. This overview is not part of the standard proper.

-

ECMAScript is object-based: basic language and host facilities -are provided by objects, and an ECMAScript program is a cluster of +

ECMAScript is object-based: basic language and host facilities +are provided by objects, and an ECMAScript program is a cluster of communicating objects. In ECMAScript, an object is a collection of zero or more properties each with attributes that determine how each property can be used—for example, when the Writable attribute for a property is set to false, - any attempt by executed ECMAScript code to assign a different value to + any attempt by executed ECMAScript code to assign a different value to the property fails. Properties are containers that hold other objects, primitive values, or functions. A primitive value is a member of one of the following built-in types: Undefined, Null, Boolean, Number, String, and Symbol; an object is a member of the built-in type Object; and a function is a callable object. A function that is associated with an object via a property is called a method.

ECMAScript defines a collection of built-in objects that round out the definition of ECMAScript entities. These built-in objects include the global object; objects that are fundamental to the runtime semantics of the language including Object, Function, Boolean, Symbol, and various Error objects; objects that represent and manipulate numeric values including Math, Number, and Date; the text processing objects String and RegExp; objects that are indexed collections of values including Array - and nine different kinds of Typed Arrays whose elements all have a + and nine different kinds of Typed Arrays whose elements all have a specific numeric data representation; keyed collections including Map and Set objects; objects supporting structured data including the JSON object, ArrayBuffer, SharedArrayBuffer, and DataView; objects supporting control abstractions including generator functions and Promise objects; and reflection objects including Proxy and Reflect.

-

ECMAScript also defines a set of built-in operators. -ECMAScript operators include various unary operations, multiplicative -operators, additive operators, bitwise shift operators, relational -operators, equality operators, binary bitwise operators, binary logical +

ECMAScript also defines a set of built-in operators. +ECMAScript operators include various unary operations, multiplicative +operators, additive operators, bitwise shift operators, relational +operators, equality operators, binary bitwise operators, binary logical operators, assignment operators, and the comma operator.

-

Large ECMAScript programs are supported by modules -which allow a program to be divided into multiple sequences of -statements and declarations. Each module explicitly identifies +

Large ECMAScript programs are supported by modules +which allow a program to be divided into multiple sequences of +statements and declarations. Each module explicitly identifies declarations it uses that need to be provided by other modules and which of its declarations are available for use by other modules.

ECMAScript syntax intentionally resembles Java syntax. ECMAScript - syntax is relaxed to enable it to serve as an easy-to-use scripting -language. For example, a variable is not required to have its type + syntax is relaxed to enable it to serve as an easy-to-use scripting +language. For example, a variable is not required to have its type declared nor are types associated with properties, and defined functions - are not required to have their declarations appear textually before + are not required to have their declarations appear textually before calls to them.

4.2.1Objects

-

Even though ECMAScript includes syntax for class definitions, -ECMAScript objects are not fundamentally class-based such as those in -C++, Smalltalk, or Java. Instead objects may be created in various ways -including via a literal notation or via constructors which -create objects and then execute code that initializes all or part of +

Even though ECMAScript includes syntax for class definitions, +ECMAScript objects are not fundamentally class-based such as those in +C++, Smalltalk, or Java. Instead objects may be created in various ways +including via a literal notation or via constructors which +create objects and then execute code that initializes all or part of them by assigning initial values to their properties. Each constructor is a function that has a property named "prototype" that is used to implement prototype-based inheritance and shared properties. Objects are created by using constructors in new expressions; for example, new Date(2009, 11) creates a new Date object. Invoking a constructor without using new has consequences that depend on the constructor. For example, Date() produces a string representation of the current date and time rather than an object.

Every object created by a constructor has an implicit reference (called the object's prototype) to the value of its constructor's "prototype" property. Furthermore, a prototype may have a non-null implicit reference to its prototype, and so on; this is called the prototype chain. - When a reference is made to a property in an object, that reference is -to the property of that name in the first object in the prototype chain -that contains a property of that name. In other words, first the object -mentioned directly is examined for such a property; if that object + When a reference is made to a property in an object, that reference is +to the property of that name in the first object in the prototype chain +that contains a property of that name. In other words, first the object +mentioned directly is examined for such a property; if that object contains the named property, that is the property to which the reference - refers; if that object does not contain the named property, the + refers; if that object does not contain the named property, the prototype for that object is examined next; and so on.

Figure 1: Object/Prototype Relationships
An image of lots of boxes and arrows.

In a class-based object-oriented language, in general, state is - carried by instances, methods are carried by classes, and inheritance + carried by instances, methods are carried by classes, and inheritance is only of structure and behaviour. In ECMAScript, the state and methods - are carried by objects, while structure, behaviour, and state are all + are carried by objects, while structure, behaviour, and state are all inherited.

-

All objects that do not directly contain a particular property +

All objects that do not directly contain a particular property that their prototype contains share that property and its value. Figure 1 illustrates this:

CF is a constructor (and also an object). Five objects have been created by using new expressions: cf1, cf2, cf3, cf4, and cf5. Each of these objects contains properties named q1 and q2. The dashed lines represent the implicit prototype relationship; so, for example, cf3's prototype is CFp. The constructor, CF, has two properties itself, named P1 and P2, which are not visible to CFp, cf1, cf2, cf3, cf4, or cf5. The property named CFP1 in CFp is shared by cf1, cf2, cf3, cf4, and cf5 (but not by CF), as are any properties found in CFp's implicit prototype chain that are not named q1, q2, or CFP1. Notice that there is no implicit prototype link between CF and CFp.

-

Unlike most class-based object languages, properties can be -added to objects dynamically by assigning values to them. That is, -constructors are not required to name or assign values to all or any of +

Unlike most class-based object languages, properties can be +added to objects dynamically by assigning values to them. That is, +constructors are not required to name or assign values to all or any of the constructed object's properties. In the above diagram, one could add a new shared property for cf1, cf2, cf3, cf4, and cf5 by assigning a new value to the property in CFp.

-

Although ECMAScript objects are not inherently class-based, it -is often convenient to define class-like abstractions based upon a +

Although ECMAScript objects are not inherently class-based, it +is often convenient to define class-like abstractions based upon a common pattern of constructor - functions, prototype objects, and methods. The ECMAScript built-in -objects themselves follow such a class-like pattern. Beginning with -ECMAScript 2015, the ECMAScript language includes syntactic class -definitions that permit programmers to concisely define objects that -conform to the same class-like abstraction pattern used by the built-in + functions, prototype objects, and methods. The ECMAScript built-in +objects themselves follow such a class-like pattern. Beginning with +ECMAScript 2015, the ECMAScript language includes syntactic class +definitions that permit programmers to concisely define objects that +conform to the same class-like abstraction pattern used by the built-in objects.

4.2.2The Strict Variant of ECMAScript

-

The ECMAScript Language recognizes the possibility that some -users of the language may wish to restrict their usage of some features -available in the language. They might do so in the interests of +

The ECMAScript Language recognizes the possibility that some +users of the language may wish to restrict their usage of some features +available in the language. They might do so in the interests of security, to avoid what they consider to be error-prone features, to get - enhanced error checking, or for other reasons of their choosing. In -support of this possibility, ECMAScript defines a strict variant of the -language. The strict variant of the language excludes some specific -syntactic and semantic features of the regular ECMAScript language and -modifies the detailed semantics of some features. The strict variant -also specifies additional error conditions that must be reported by + enhanced error checking, or for other reasons of their choosing. In +support of this possibility, ECMAScript defines a strict variant of the +language. The strict variant of the language excludes some specific +syntactic and semantic features of the regular ECMAScript language and +modifies the detailed semantics of some features. The strict variant +also specifies additional error conditions that must be reported by throwing error exceptions in situations that are not specified as errors by the non-strict form of the language.

The strict variant of ECMAScript is commonly referred to as the strict mode - of the language. Strict mode selection and use of the strict mode -syntax and semantics of ECMAScript is explicitly made at the level of + of the language. Strict mode selection and use of the strict mode +syntax and semantics of ECMAScript is explicitly made at the level of individual ECMAScript source text units. Because strict mode is selected - at the level of a syntactic source text unit, strict mode only imposes -restrictions that have local effect within such a source text unit. -Strict mode does not restrict or modify any aspect of the ECMAScript -semantics that must operate consistently across multiple source text + at the level of a syntactic source text unit, strict mode only imposes +restrictions that have local effect within such a source text unit. +Strict mode does not restrict or modify any aspect of the ECMAScript +semantics that must operate consistently across multiple source text units. A complete ECMAScript program may be composed of both strict mode - and non-strict mode ECMAScript source text units. In this case, strict -mode only applies when actually executing code that is defined within a + and non-strict mode ECMAScript source text units. In this case, strict +mode only applies when actually executing code that is defined within a strict mode source text unit.

-

In order to conform to this specification, an ECMAScript -implementation must implement both the full unrestricted ECMAScript +

In order to conform to this specification, an ECMAScript +implementation must implement both the full unrestricted ECMAScript language and the strict variant of the ECMAScript language as defined by - this specification. In addition, an implementation must support the -combination of unrestricted and strict mode source text units into a + this specification. In addition, an implementation must support the +combination of unrestricted and strict mode source text units into a single composite program.

 @@ -470,9 +470,9 @@ single composite program.

object that provides shared properties for other objects

Note

When a constructor creates an object, that object implicitly references the constructor's prototype property for the purpose of resolving property references. The constructor's prototype property can be referenced by the program expression constructor.prototype, - and properties added to an object's prototype are shared, through -inheritance, by all objects sharing the prototype. Alternatively, a new -object may be created with an explicitly specified prototype by using + and properties added to an object's prototype are shared, through +inheritance, by all objects sharing the prototype. Alternatively, a new +object may be created with an explicitly specified prototype by using the Object.create built-in function.

 @@ -499,8 +499,8 @@ the Object.create built-in function.

4.3.9built-in object

object specified and supplied by an ECMAScript implementation

Note
-

Standard built-in objects are defined in this specification. -An ECMAScript implementation may specify and supply additional kinds of +

Standard built-in objects are defined in this specification. +An ECMAScript implementation may specify and supply additional kinds of built-in objects. A built-in constructor is a built-in object that is also a constructor.

 @@ -543,8 +543,8 @@ built-in objects. A built-in member of the Object type that is an instance of the standard built-in Boolean constructor

Note

A Boolean object is created by using the Boolean constructor in a new - expression, supplying a Boolean value as an argument. The resulting -object has an internal slot whose value is the Boolean value. A Boolean + expression, supplying a Boolean value as an argument. The resulting +object has an internal slot whose value is the Boolean value. A Boolean object can be coerced to a Boolean value.

 @@ -553,10 +553,10 @@ object can be coerced to a Boolean value.

4.3.17String value

primitive value that is a finite ordered sequence of zero or more 16-bit unsigned integer values

Note
-

A String value is a member of the String type. Each integer -value in the sequence usually represents a single 16-bit unit of UTF-16 -text. However, ECMAScript does not place any restrictions or -requirements on the values except that they must be 16-bit unsigned +

A String value is a member of the String type. Each integer +value in the sequence usually represents a single 16-bit unit of UTF-16 +text. However, ECMAScript does not place any restrictions or +requirements on the values except that they must be 16-bit unsigned integers.

 @@ -571,8 +571,8 @@ integers.

member of the Object type that is an instance of the standard built-in String constructor

Note

A String object is created by using the String constructor in a new - expression, supplying a String value as an argument. The resulting -object has an internal slot whose value is the String value. A String + expression, supplying a String value as an argument. The resulting +object has an internal slot whose value is the String value. A String object can be coerced to a String value by calling the String constructor as a function (21.1.1.1).

 @@ -595,8 +595,8 @@ object can be coerced to a String value by calling the String member of the Object type that is an instance of the standard built-in Number constructor

Note

A Number object is created by using the Number constructor in a new - expression, supplying a number value as an argument. The resulting -object has an internal slot whose value is the number value. A Number + expression, supplying a number value as an argument. The resulting +object has an internal slot whose value is the number value. A Number object can be coerced to a number value by calling the Number constructor as a function (20.1.1.1).

 @@ -648,8 +648,8 @@ object can be coerced to a number value by calling the Number 4.3.30property

part of an object that associates a key (either a String value or a Symbol value) and a value

Note
-

Depending upon the form of the property the value may be -represented either directly as a data value (a primitive value, an +

Depending upon the form of the property the value may be +represented either directly as a data value (a primitive value, an object, or a function object) or indirectly by a pair of accessor functions.

 @@ -666,8 +666,8 @@ object, or a 4.3.32built-in method

method that is a built-in function

Note
-

Standard built-in methods are defined in this specification, -and an ECMAScript implementation may specify and provide other +

Standard built-in methods are defined in this specification, +and an ECMAScript implementation may specify and provide other additional built-in methods.

 @@ -693,13 +693,13 @@ additional built-in methods.

The remainder of this specification is organized as follows:

Clause 5 defines the notational conventions used throughout the specification.

Clauses 6-9 define the execution environment within which ECMAScript programs operate.

-

Clauses 10-16 define the actual ECMAScript programming language -including its syntactic encoding and the execution semantics of all +

Clauses 10-16 define the actual ECMAScript programming language +including its syntactic encoding and the execution semantics of all language features.

-

Clauses 17-26 define the ECMAScript standard library. They -include the definitions of all of the standard objects that are +

Clauses 17-26 define the ECMAScript standard library. They +include the definitions of all of the standard objects that are available for use by ECMAScript programs as they execute.

-

Clause 27 describes the memory consistency model of accesses on +

Clause 27 describes the memory consistency model of accesses on SharedArrayBuffer-backed memory and methods of the Atomics object.

@@ -715,26 +715,26 @@ SharedArrayBuffer-backed memory and methods of the Atomics object.

A context-free grammar consists of a number of productions. Each production has an abstract symbol called a nonterminal as its left-hand side, and a sequence of zero or more nonterminal and terminal symbols as its right-hand side. For each grammar, the terminal symbols are drawn from a specified alphabet.

A chain production is a production that has exactly one nonterminal symbol on its right-hand side along with zero or more terminal symbols.

Starting from a sentence consisting of a single distinguished nonterminal, called the goal symbol, a given context-free grammar specifies a language, - namely, the (perhaps infinite) set of possible sequences of terminal + namely, the (perhaps infinite) set of possible sequences of terminal symbols that can result from repeatedly replacing any nonterminal in the - sequence with a right-hand side of a production for which the + sequence with a right-hand side of a production for which the nonterminal is the left-hand side.

5.1.2The Lexical and RegExp Grammars

A lexical grammar for ECMAScript is given in clause 11. This grammar has as its terminal symbols Unicode code points that conform to the rules for SourceCharacter defined in 10.1. It defines a set of productions, starting from the goal symbol InputElementDiv, InputElementTemplateTail, or InputElementRegExp, or InputElementRegExpOrTemplateTail, that describe how sequences of such code points are translated into a sequence of input elements.

-

Input elements other than white space and comments form the +

Input elements other than white space and comments form the terminal symbols for the syntactic grammar for ECMAScript and are called - ECMAScript tokens. These tokens are the reserved words, -identifiers, literals, and punctuators of the ECMAScript language. -Moreover, line terminators, although not considered to be tokens, also -become part of the stream of input elements and guide the process of + ECMAScript tokens. These tokens are the reserved words, +identifiers, literals, and punctuators of the ECMAScript language. +Moreover, line terminators, although not considered to be tokens, also +become part of the stream of input elements and guide the process of automatic semicolon insertion (11.9). - Simple white space and single-line comments are discarded and do not + Simple white space and single-line comments are discarded and do not appear in the stream of input elements for the syntactic grammar. A MultiLineComment (that is, a comment of the form /*…*/ regardless of whether it spans more than one line) is likewise simply discarded if it contains no line terminator; but if a MultiLineComment - contains one or more line terminators, then it is replaced by a single -line terminator, which becomes part of the stream of input elements for + contains one or more line terminators, then it is replaced by a single +line terminator, which becomes part of the stream of input elements for the syntactic grammar.

A RegExp grammar for ECMAScript is given in 21.2.1. This grammar also has as its terminal symbols the code points as defined by SourceCharacter. It defines a set of productions, starting from the goal symbol Pattern, that describe how sequences of code points are translated into regular expression patterns.

Productions of the lexical and RegExp grammars are distinguished by having two colons “::” as separating punctuation. The lexical and RegExp grammars share some productions.

@@ -742,37 +742,37 @@ the syntactic grammar.

5.1.3The Numeric String Grammar

-

Another grammar is used for translating Strings into numeric -values. This grammar is similar to the part of the lexical grammar +

Another grammar is used for translating Strings into numeric +values. This grammar is similar to the part of the lexical grammar having to do with numeric literals and has as its terminal symbols SourceCharacter. This grammar appears in 7.1.3.1.

Productions of the numeric string grammar are distinguished by having three colons “:::” as punctuation.

5.1.4The Syntactic Grammar

-

The syntactic grammar for ECMAScript is given in -clauses 11, 12, 13, 14, and 15. This grammar has ECMAScript tokens +

The syntactic grammar for ECMAScript is given in +clauses 11, 12, 13, 14, and 15. This grammar has ECMAScript tokens defined by the lexical grammar as its terminal symbols (5.1.2). It defines a set of productions, starting from two alternative goal symbols Script and Module, that describe how sequences of tokens form syntactically correct independent components of ECMAScript programs.

When a stream of code points is to be parsed as an ECMAScript Script or Module, - it is first converted to a stream of input elements by repeated -application of the lexical grammar; this stream of input elements is -then parsed by a single application of the syntactic grammar. The input -stream is syntactically in error if the tokens in the stream of input + it is first converted to a stream of input elements by repeated +application of the lexical grammar; this stream of input elements is +then parsed by a single application of the syntactic grammar. The input +stream is syntactically in error if the tokens in the stream of input elements cannot be parsed as a single instance of the goal nonterminal (Script or Module), with no tokens left over.

When a parse is successful, it constructs a parse tree, a rooted tree structure in which each node is a Parse Node. Each Parse Node is an instance - of a symbol in the grammar; it represents a span of the source text -that can be derived from that symbol. The root node of the parse tree, + of a symbol in the grammar; it represents a span of the source text +that can be derived from that symbol. The root node of the parse tree, representing the whole of the source text, is an instance of the parse's goal symbol. - When a Parse Node is an instance of a nonterminal, it is also an -instance of some production that has that nonterminal as its left-hand -side. Moreover, it has zero or more children, one for each -symbol on the production's right-hand side: each child is a Parse Node + When a Parse Node is an instance of a nonterminal, it is also an +instance of some production that has that nonterminal as its left-hand +side. Moreover, it has zero or more children, one for each +symbol on the production's right-hand side: each child is a Parse Node that is an instance of the corresponding symbol.

-

New Parse Nodes are instantiated for each invocation of the -parser and never reused between parses even of identical source text. -Parse Nodes are considered the same Parse Node if and only -if they represent the same span of source text, are instances of the +

New Parse Nodes are instantiated for each invocation of the +parser and never reused between parses even of identical source text. +Parse Nodes are considered the same Parse Node if and only +if they represent the same span of source text, are instances of the same grammar symbol, and resulted from the same parser invocation.

Note 1

Parsing the same String multiple times will lead to different Parse Nodes, e.g., as occurs in:

@@ -781,15 +781,15 @@ same grammar symbol, and resulted from the same parser invocation.

Note 2
Parse Nodes are specification artefacts, and implementations are not required to use an analogous data structure.

Productions of the syntactic grammar are distinguished by having just one colon “:” as punctuation.

The syntactic grammar as presented in clauses 12, 13, 14 and 15 - is not a complete account of which token sequences are accepted as a + is not a complete account of which token sequences are accepted as a correct ECMAScript Script or Module. - Certain additional token sequences are also accepted, namely, those -that would be described by the grammar if only semicolons were added to -the sequence in certain places (such as before line terminator -characters). Furthermore, certain token sequences that are described by + Certain additional token sequences are also accepted, namely, those +that would be described by the grammar if only semicolons were added to +the sequence in certain places (such as before line terminator +characters). Furthermore, certain token sequences that are described by the grammar are not considered acceptable if a line terminator character appears in certain “awkward” places.

-

In certain cases, in order to avoid ambiguities, the syntactic +

In certain cases, in order to avoid ambiguities, the syntactic grammar uses generalized productions that permit token sequences that do not form a valid ECMAScript Script or Module. For example, this technique is used for object literals and object destructuring patterns. In such cases a more restrictive supplemental grammar is provided that further restricts the acceptable token sequences. Typically, an early error rule will then define an error condition if "P is not covering an N", where P is a Parse Node (an instance of the generalized production) and N is a nonterminal from the supplemental grammar. Here, the sequence of tokens originally matched by P is parsed again using N as the goal symbol. (If N takes grammatical parameters, then they are set to the same values used when P was originally parsed.) An error occurs if the sequence of tokens cannot be parsed as a single instance of N, with no tokens left over. Subsequently, algorithms access the result of the parse using a phrase of the form "the N that is covered by P". This will always be a Parse Node (an instance of N, unique for a given P), since any parsing failure would have been detected by an early error rule.

@@ -797,17 +797,17 @@ grammar uses generalized productions that permit token sequences that do

5.1.5Grammar Notation

Terminal symbols of the lexical, RegExp, and numeric string grammars are shown in fixed width - font, both in the productions of the grammars and throughout this -specification whenever the text directly refers to such a terminal + font, both in the productions of the grammars and throughout this +specification whenever the text directly refers to such a terminal symbol. These are to appear in a script exactly as written. All terminal - symbol code points specified in this way are to be understood as the -appropriate Unicode code points from the Basic Latin range, as opposed + symbol code points specified in this way are to be understood as the +appropriate Unicode code points from the Basic Latin range, as opposed to any similar-looking code points from other Unicode ranges.

-

Nonterminal symbols are shown in italic type. The -definition of a nonterminal (also called a “production”) is introduced -by the name of the nonterminal being defined followed by one or more -colons. (The number of colons indicates to which grammar the production -belongs.) One or more alternative right-hand sides for the nonterminal +

Nonterminal symbols are shown in italic type. The +definition of a nonterminal (also called a “production”) is introduced +by the name of the nonterminal being defined followed by one or more +colons. (The number of colons indicates to which grammar the production +belongs.) One or more alternative right-hand sides for the nonterminal then follow on succeeding lines. For example, the syntactic definition:

WhileStatement:while(Expression)Statement @@ -819,9 +819,9 @@ then follow on succeeding lines. For example, the syntactic definition:

states that an ArgumentList may represent either a single AssignmentExpression or an ArgumentList, followed by a comma, followed by an AssignmentExpression. This definition of ArgumentList is recursive, that is, it is defined in terms of itself. The result is that an ArgumentList may contain any positive number of arguments, separated by commas, where each argument expression is an AssignmentExpression. Such recursive definitions of nonterminals are common.

The subscripted suffix “opt”, which may appear after - a terminal or nonterminal, indicates an optional symbol. The -alternative containing the optional symbol actually specifies two -right-hand sides, one that omits the optional element and one that + a terminal or nonterminal, indicates an optional symbol. The +alternative containing the optional symbol actually specifies two +right-hand sides, one that omits the optional element and one that includes it. This means that:

VariableDeclaration:BindingIdentifierInitializeropt @@ -849,9 +849,9 @@ includes it. This means that:

so, in this example, the nonterminal IterationStatement actually has four alternative right-hand sides.

A production may be parameterized by a subscripted annotation of the form “[parameters]”, which may appear as a suffix to the nonterminal symbol defined by the production. “parameters” - may be either a single name or a comma separated list of names. A -parameterized production is shorthand for a set of productions defining -all combinations of the parameter names, preceded by an underscore, + may be either a single name or a comma separated list of names. A +parameterized production is shorthand for a set of productions defining +all combinations of the parameter names, preceded by an underscore, appended to the parameterized nonterminal symbol. This means that:

StatementList[Return]:ReturnStatement @@ -888,8 +888,8 @@ appended to the parameterized nonterminal symbol. This means that:

StatementList_Return_In:ReturnStatement ExpressionStatement -

Multiple parameters produce a combinatory number of -productions, not all of which are necessarily referenced in a complete +

Multiple parameters produce a combinatory number of +productions, not all of which are necessarily referenced in a complete grammar.

References to nonterminals on the right-hand side of a production can also be parameterized. For example:

@@ -920,9 +920,9 @@ grammar.

VariableDeclaration:BindingIdentifier BindingIdentifierInitializer_In -

Prefixing a parameter name with “?” on a right-hand +

Prefixing a parameter name with “?” on a right-hand side nonterminal reference makes that parameter value dependent upon the - occurrence of the parameter name on the reference to the current + occurrence of the parameter name on the reference to the current production's left-hand side symbol. For example:

VariableDeclaration[In]:BindingIdentifierInitializer[?In] @@ -934,10 +934,10 @@ production's left-hand side symbol. For example:

VariableDeclaration_In:BindingIdentifierInitializer_In -

If a right-hand side alternative is prefixed with +

If a right-hand side alternative is prefixed with “[+parameter]” that alternative is only available if the named parameter - was used in referencing the production's nonterminal symbol. If a -right-hand side alternative is prefixed with “[~parameter]” that + was used in referencing the production's nonterminal symbol. If a +right-hand side alternative is prefixed with “[~parameter]” that alternative is only available if the named parameter was not used in referencing the production's nonterminal symbol. This means that:

StatementList[Return]:[+Return]ReturnStatement @@ -965,8 +965,8 @@ alternative is only available if the named parameter was not used in r StatementList_Return:ExpressionStatement

When the words “one of” follow the colon(s) in a grammar - definition, they signify that each of the terminal symbols on the -following line or lines is an alternative definition. For example, the + definition, they signify that each of the terminal symbols on the +following line or lines is an alternative definition. For example, the lexical grammar for ECMAScript contains the production:

NonZeroDigit::one of123456789 @@ -983,16 +983,16 @@ lexical grammar for ECMAScript contains the production:

8 9 -

If the phrase “[empty]” appears as the right-hand side of a -production, it indicates that the production's right-hand side contains +

If the phrase “[empty]” appears as the right-hand side of a +production, it indicates that the production's right-hand side contains no terminals or nonterminals.

-

If the phrase “[lookahead ∉ set]” appears in the -right-hand side of a production, it indicates that the production may -not be used if the immediately following input token sequence is a +

If the phrase “[lookahead ∉ set]” appears in the +right-hand side of a production, it indicates that the production may +not be used if the immediately following input token sequence is a member of the given set. The set can be written as - a comma separated list of one or two element terminal sequences + a comma separated list of one or two element terminal sequences enclosed in curly brackets. For convenience, the set can also be written - as a nonterminal, in which case it represents the set of all terminals + as a nonterminal, in which case it represents the set of all terminals to which that nonterminal could expand. If the set consists of a single terminal the phrase “[lookahead ≠ terminal]” may be used.

For example, given the definitions:

@@ -1009,8 +1009,8 @@ to which that nonterminal could expand. If the set consists of a sing

matches either the letter n followed by one or more decimal digits the first of which is even, or a decimal digit not followed by another decimal digit.

Similarly, if the phrase “[lookahead ∈ set]” appears - in the right-hand side of a production, it indicates that the -production may only be used if the immediately following input token + in the right-hand side of a production, it indicates that the +production may only be used if the immediately following input token sequence is a member of the given set. If the set consists of a single terminal the phrase “[lookahead = terminal]” may be used.

If the phrase “[no LineTerminator here]” appears in the right-hand side of a production of the syntactic grammar, it indicates that the production is a restricted production: it may not be used if a LineTerminator occurs in the input stream at the indicated position. For example, the production:

@@ -1018,18 +1018,18 @@ sequence is a member of the given set. If the set consists

indicates that the production may not be used if a LineTerminator occurs in the script between the throw token and the Expression.

Unless the presence of a LineTerminator is forbidden by a restricted production, any number of occurrences of LineTerminator - may appear between any two consecutive tokens in the stream of input + may appear between any two consecutive tokens in the stream of input elements without affecting the syntactic acceptability of the script.

-

When an alternative in a production of the lexical grammar or -the numeric string grammar appears to be a multi-code point token, it +

When an alternative in a production of the lexical grammar or +the numeric string grammar appears to be a multi-code point token, it represents the sequence of code points that would make up such a token.

The right-hand side of a production may specify that certain expansions are not permitted by using the phrase “but not” and then indicating the expansions to be excluded. For example, the production:

Identifier::IdentifierNamebut not ReservedWord

means that the nonterminal Identifier may be replaced by any sequence of code points that could replace IdentifierName provided that the same sequence of code points could not replace ReservedWord.

-

Finally, a few nonterminal symbols are described by a -descriptive phrase in sans-serif type in cases where it would be +

Finally, a few nonterminal symbols are described by a +descriptive phrase in sans-serif type in cases where it would be impractical to list all the alternatives:

SourceCharacter::any Unicode code point @@ -1039,39 +1039,39 @@ impractical to list all the alternatives:

5.2Algorithm Conventions

-

The specification often uses a numbered list to specify steps in -an algorithm. These algorithms are used to precisely specify the +

The specification often uses a numbered list to specify steps in +an algorithm. These algorithms are used to precisely specify the required semantics of ECMAScript language constructs. The algorithms are not intended to imply the use of any specific implementation technique. - In practice, there may be more efficient algorithms available to + In practice, there may be more efficient algorithms available to implement a given feature.

-

Algorithms may be explicitly parameterized, in which case the -names and usage of the parameters must be provided as part of the +

Algorithms may be explicitly parameterized, in which case the +names and usage of the parameters must be provided as part of the algorithm's definition.

-

Algorithm steps may be subdivided into sequential substeps. -Substeps are indented and may themselves be further divided into -indented substeps. Outline numbering conventions are used to identify -substeps with the first level of substeps labelled with lower case -alphabetic characters and the second level of substeps labelled with -lower case roman numerals. If more than three levels are required these +

Algorithm steps may be subdivided into sequential substeps. +Substeps are indented and may themselves be further divided into +indented substeps. Outline numbering conventions are used to identify +substeps with the first level of substeps labelled with lower case +alphabetic characters and the second level of substeps labelled with +lower case roman numerals. If more than three levels are required these rules repeat with the fourth level using numeric labels. For example:

  1. Top-level step
    1. Substep.
    2. Substep.
      1. Subsubstep.
        1. Subsubsubstep
          1. Subsubsubsubstep
            1. Subsubsubsubsubstep
-

A step or substep may be written as an “if” predicate that -conditions its substeps. In this case, the substeps are only applied if +

A step or substep may be written as an “if” predicate that +conditions its substeps. In this case, the substeps are only applied if the predicate is true. If a step or substep begins with the word “else”, - it is a predicate that is the negation of the preceding “if” predicate + it is a predicate that is the negation of the preceding “if” predicate step at the same level.

A step may specify the iterative application of its substeps.

-

A step that begins with “Assert:” asserts -an invariant condition of its algorithm. Such assertions are used to -make explicit algorithmic invariants that would otherwise be implicit. -Such assertions add no additional semantic requirements and hence need -not be checked by an implementation. They are used simply to clarify +

A step that begins with “Assert:” asserts +an invariant condition of its algorithm. Such assertions are used to +make explicit algorithmic invariants that would otherwise be implicit. +Such assertions add no additional semantic requirements and hence need +not be checked by an implementation. They are used simply to clarify algorithms.

Algorithm steps may declare named aliases for any value using the form “Let x be someValue”. These aliases are reference-like in that both x and someValue - refer to the same underlying data and modifications to either are -visible to both. Algorithm steps that want to avoid this reference-like + refer to the same underlying data and modifications to either are +visible to both. Algorithm steps that want to avoid this reference-like behaviour should explicitly make a copy of the right-hand side: “Let x be a copy of someValue” creates a shallow copy of someValue.

Once declared, an alias may be referenced in any subsequent steps and must not be referenced from steps prior to the alias's declaration. @@ -1082,52 +1082,52 @@ behaviour should explicitly make a copy of the right-hand side: “Let xIn order to facilitate their use in multiple parts of this specification, some algorithms, called abstract operations, are named and written in parameterized functional form so that they may be referenced by name from within other algorithms. Abstract operations - are typically referenced using a functional application style such as -OperationName(arg1, arg2). Some abstract -operations are treated as polymorphically dispatched methods of -class-like specification abstractions. Such method-like abstract -operations are typically referenced using a method application style + are typically referenced using a functional application style such as +OperationName(arg1, arg2). Some abstract +operations are treated as polymorphically dispatched methods of +class-like specification abstractions. Such method-like abstract +operations are typically referenced using a method application style such as someValue.OperationName(arg1, arg2).

5.2.2Syntax-Directed Operations

-

A syntax-directed operation is a named operation -whose definition consists of algorithms, each of which is associated -with one or more productions from one of the ECMAScript grammars. A +

A syntax-directed operation is a named operation +whose definition consists of algorithms, each of which is associated +with one or more productions from one of the ECMAScript grammars. A production that has multiple alternative definitions will typically have - a distinct algorithm for each alternative. When an algorithm is -associated with a grammar production, it may reference the terminal and -nonterminal symbols of the production alternative as if they were -parameters of the algorithm. When used in this manner, nonterminal -symbols refer to the actual alternative definition that is matched when -parsing the source text. The source text matched by a -grammar production is the portion of the source text that starts at the -beginning of the first terminal that participated in the match and ends + a distinct algorithm for each alternative. When an algorithm is +associated with a grammar production, it may reference the terminal and +nonterminal symbols of the production alternative as if they were +parameters of the algorithm. When used in this manner, nonterminal +symbols refer to the actual alternative definition that is matched when +parsing the source text. The source text matched by a +grammar production is the portion of the source text that starts at the +beginning of the first terminal that participated in the match and ends at the end of the last terminal that participated in the match.

-

When an algorithm is associated with a production alternative, -the alternative is typically shown without any “[ ]” grammar -annotations. Such annotations should only affect the syntactic -recognition of the alternative and have no effect on the associated +

When an algorithm is associated with a production alternative, +the alternative is typically shown without any “[ ]” grammar +annotations. Such annotations should only affect the syntactic +recognition of the alternative and have no effect on the associated semantics for the alternative.

-

Syntax-directed operations are invoked with a parse node and, +

Syntax-directed operations are invoked with a parse node and, optionally, other parameters by using the conventions on steps 1, 3, and 4 in the following algorithm:

  1. Let status be the result of performing SyntaxDirectedOperation of SomeNonTerminal.
  2. Let someParseNode be the parse of some source text.
  3. Perform SyntaxDirectedOperation of someParseNode.
  4. Perform SyntaxDirectedOperation of someParseNode passing "value" as the argument.
-

Unless explicitly specified otherwise, all chain productions +

Unless explicitly specified otherwise, all chain productions have an implicit definition for every operation that might be applied to - that production's left-hand side nonterminal. The implicit definition + that production's left-hand side nonterminal. The implicit definition simply reapplies the same operation with the same parameters, if any, to the chain production's - sole right-hand side nonterminal and then returns the result. For -example, assume that some algorithm has a step of the form: “Return the + sole right-hand side nonterminal and then returns the result. For +example, assume that some algorithm has a step of the form: “Return the result of evaluating Block” and that there is a production:

Block:{StatementList} -

but the Evaluation operation does not associate an algorithm -with that production. In that case, the Evaluation operation implicitly +

but the Evaluation operation does not associate an algorithm +with that production. In that case, the Evaluation operation implicitly includes an association of the form:

Runtime Semantics: Evaluation

@@ -1217,43 +1217,43 @@ includes an association of the form:

5.2.4Static Semantics

-

Context-free grammars are not sufficiently powerful to express -all the rules that define whether a stream of input elements form a +

Context-free grammars are not sufficiently powerful to express +all the rules that define whether a stream of input elements form a valid ECMAScript Script or Module - that may be evaluated. In some situations additional rules are needed -that may be expressed using either ECMAScript algorithm conventions or -prose requirements. Such rules are always associated with a production + that may be evaluated. In some situations additional rules are needed +that may be expressed using either ECMAScript algorithm conventions or +prose requirements. Such rules are always associated with a production of a grammar and are called the static semantics of the production.

-

Static Semantic Rules have names and typically are defined -using an algorithm. Named Static Semantic Rules are associated with -grammar productions and a production that has multiple alternative -definitions will typically have for each alternative a distinct +

Static Semantic Rules have names and typically are defined +using an algorithm. Named Static Semantic Rules are associated with +grammar productions and a production that has multiple alternative +definitions will typically have for each alternative a distinct algorithm for each applicable named static semantic rule.

Unless otherwise specified every grammar production alternative in this specification implicitly has a definition for a static semantic - rule named Contains which takes an argument named symbol -whose value is a terminal or nonterminal of the grammar that includes + rule named Contains which takes an argument named symbol +whose value is a terminal or nonterminal of the grammar that includes the associated production. The default definition of Contains is:

  1. For each child node child of this Parse Node, do
    1. If child is an instance of symbol, return true.
    2. If child is an instance of a nonterminal, then
      1. Let contained be the result of child Contains symbol.
      2. If contained is true, return true.
  2. Return false.

The above definition is explicitly over-ridden for specific productions.

A special kind of static semantic rule is an Early Error Rule. Early error rules define early error conditions (see clause 16) that are associated with specific grammar productions. Evaluation of most early error - rules are not explicitly invoked within the algorithms of this -specification. A conforming implementation must, prior to the first + rules are not explicitly invoked within the algorithms of this +specification. A conforming implementation must, prior to the first evaluation of a Script or Module, validate all of the early error rules of the productions used to parse that Script or Module. If any of the early error rules are violated the Script or Module is invalid and cannot be evaluated.

5.2.5Mathematical Operations

-

Mathematical operations such as addition, subtraction, -negation, multiplication, division, and the mathematical functions -defined later in this clause should always be understood as computing -exact mathematical results on mathematical real numbers, which unless -otherwise noted do not include infinities and do not include a negative -zero that is distinguished from positive zero. Algorithms in this -standard that model floating-point arithmetic include explicit steps, -where necessary, to handle infinities and signed zero and to perform -rounding. If a mathematical operation or function is applied to a -floating-point number, it should be understood as being applied to the +

Mathematical operations such as addition, subtraction, +negation, multiplication, division, and the mathematical functions +defined later in this clause should always be understood as computing +exact mathematical results on mathematical real numbers, which unless +otherwise noted do not include infinities and do not include a negative +zero that is distinguished from positive zero. Algorithms in this +standard that model floating-point arithmetic include explicit steps, +where necessary, to handle infinities and signed zero and to perform +rounding. If a mathematical operation or function is applied to a +floating-point number, it should be understood as being applied to the exact mathematical value represented by that floating-point number; such a floating-point number must be finite, and if it is +0 or -0 then the corresponding mathematical value is simply 0.

The mathematical function abs(x) produces the absolute value of x, which is -x if x is negative (less than zero) and otherwise is x itself.

@@ -1269,20 +1269,20 @@ exact mathematical value represented by that floating-point number; such

6ECMAScript Data Types and Values

-

Algorithms within this specification manipulate values each of +

Algorithms within this specification manipulate values each of which has an associated type. The possible value types are exactly those defined in this clause. Types are further subclassified into ECMAScript language types and specification types.

Within this specification, the notation “Type(x)” is used as shorthand for “the type of x” - where “type” refers to the ECMAScript language and specification types -defined in this clause. When the term “empty” is used as if it was + where “type” refers to the ECMAScript language and specification types +defined in this clause. When the term “empty” is used as if it was naming a value, it is equivalent to saying “no value of any type”.

6.1ECMAScript Language Types

-

An ECMAScript language type corresponds to values -that are directly manipulated by an ECMAScript programmer using the -ECMAScript language. The ECMAScript language types are Undefined, Null, +

An ECMAScript language type corresponds to values +that are directly manipulated by an ECMAScript programmer using the +ECMAScript language. The ECMAScript language types are Undefined, Null, Boolean, String, Symbol, Number, and Object. An ECMAScript language value is a value that is characterized by an ECMAScript language type.

@@ -1302,50 +1302,50 @@ Boolean, String, Symbol, Number, and Object. An ECMAScript language value<

6.1.4The String Type

-

The String type is the set of all ordered sequences of zero or -more 16-bit unsigned integer values (“elements”) up to a maximum length -of 253 - 1 elements. The String type is generally used to -represent textual data in a running ECMAScript program, in which case -each element in the String is treated as a UTF-16 code unit value. Each -element is regarded as occupying a position within the sequence. These -positions are indexed with nonnegative integers. The first element (if +

The String type is the set of all ordered sequences of zero or +more 16-bit unsigned integer values (“elements”) up to a maximum length +of 253 - 1 elements. The String type is generally used to +represent textual data in a running ECMAScript program, in which case +each element in the String is treated as a UTF-16 code unit value. Each +element is regarded as occupying a position within the sequence. These +positions are indexed with nonnegative integers. The first element (if any) is at index 0, the next element (if any) at index 1, and so on. The - length of a String is the number of elements (i.e., 16-bit values) -within it. The empty String has length zero and therefore contains no + length of a String is the number of elements (i.e., 16-bit values) +within it. The empty String has length zero and therefore contains no elements.

-

ECMAScript operations that do not interpret String contents -apply no further semantics. Operations that do interpret String values -treat each element as a single UTF-16 code unit. However, ECMAScript -does not restrict the value of or relationships between these code +

ECMAScript operations that do not interpret String contents +apply no further semantics. Operations that do interpret String values +treat each element as a single UTF-16 code unit. However, ECMAScript +does not restrict the value of or relationships between these code units, so operations that further interpret String contents as sequences - of Unicode code points encoded in UTF-16 must account for ill-formed + of Unicode code points encoded in UTF-16 must account for ill-formed subsequences. Such operations apply special treatment to every code unit - with a numeric value in the inclusive range 0xD800 to 0xDBFF (defined + with a numeric value in the inclusive range 0xD800 to 0xDBFF (defined by the Unicode Standard as a leading surrogate, or more formally as a high-surrogate code unit) and every code unit with a numeric value in the inclusive range 0xDC00 to 0xDFFF (defined as a trailing surrogate, or more formally as a low-surrogate code unit) using the following rules:

The function String.prototype.normalize (see 21.1.3.12) can be used to explicitly normalize a String value. String.prototype.localeCompare (see 21.1.3.10) internally normalizes String values, but no other operations implicitly normalize the strings upon which they operate. Only operations that are - explicitly specified to be language or locale sensitive produce + explicitly specified to be language or locale sensitive produce language-sensitive results.

Note
-

The rationale behind this design was to keep the -implementation of Strings as simple and high-performing as possible. If -ECMAScript source text is in Normalized Form C, string literals are -guaranteed to also be normalized, as long as they do not contain any +

The rationale behind this design was to keep the +implementation of Strings as simple and high-performing as possible. If +ECMAScript source text is in Normalized Form C, string literals are +guaranteed to also be normalized, as long as they do not contain any Unicode escape sequences.

In this specification, the phrase "the string-concatenation of A, B, @@ -1363,13 +1363,13 @@ Unicode escape sequences.

6.1.5.1Well-Known Symbols

-

Well-known symbols are built-in Symbol values that are -explicitly referenced by algorithms of this specification. They are +

Well-known symbols are built-in Symbol values that are +explicitly referenced by algorithms of this specification. They are typically used as the keys of properties whose values serve as extension - points of a specification algorithm. Unless otherwise specified, + points of a specification algorithm. Unless otherwise specified, well-known symbols values are shared by all realms (8.2).

-

Within this specification a well-known symbol is referred to -by using a notation of the form @@name, where “name” is one of the +

Within this specification a well-known symbol is referred to +by using a notation of the form @@name, where “name” is one of the values listed in Table 1.

Table 1: Well-known Symbols
@@ -1377,187 +1377,187 @@ values listed in Tabl @@ -1569,22 +1569,22 @@ method

6.1.6The Number Type

The Number type has exactly 18437736874454810627 (that is, 264 - 253 + 3) - values, representing the double-precision 64-bit format IEEE 754-2008 -values as specified in the IEEE Standard for Binary Floating-Point + values, representing the double-precision 64-bit format IEEE 754-2008 +values as specified in the IEEE Standard for Binary Floating-Point Arithmetic, except that the 9007199254740990 (that is, 253 - 2) distinct “Not-a-Number” values of the IEEE Standard are represented in ECMAScript as a single special NaN value. (Note that the NaN value is produced by the program expression NaN.) - In some implementations, external code might be able to detect a -difference between various Not-a-Number values, but such behaviour is + In some implementations, external code might be able to detect a +difference between various Not-a-Number values, but such behaviour is implementation-dependent; to ECMAScript code, all NaN values are indistinguishable from each other.

Note

The bit pattern that might be observed in an ArrayBuffer (see 24.1) or a SharedArrayBuffer (see 24.2) - after a Number value has been stored into it is not necessarily the -same as the internal representation of that Number value used by the + after a Number value has been stored into it is not necessarily the +same as the internal representation of that Number value used by the ECMAScript implementation.

There are two other special values, called positive Infinity and negative Infinity. For brevity, these values are also referred to for expository purposes by the symbols +∞ and -∞, respectively. (Note that these two infinite Number values are produced by the program expressions +Infinity (or simply Infinity) and -Infinity.)

The other 18437736874454810624 (that is, 264 - 253) - values are called the finite numbers. Half of these are positive -numbers and half are negative numbers; for every finite positive Number + values are called the finite numbers. Half of these are positive +numbers and half are negative numbers; for every finite positive Number value there is a corresponding negative value having the same magnitude.

Note that there is both a positive zero and a negative zero. For brevity, these values are also referred to for expository purposes by the symbols +0 and -0, respectively. (Note that these two different zero Number values are produced by the program expressions +0 (or simply 0) and -0.)

The 18437736874454810622 (that is, 264 - 253 - 2) finite nonzero values are of two kinds:

@@ -1601,14 +1601,14 @@ value there is a corresponding negative value having the same magnitude.

Note that all the positive and negative integers whose magnitude is no greater than 253 are representable in the Number type (indeed, the integer 0 has two representations, +0 and -0).

A finite number has an odd significand if it is nonzero and the integer m used to express it (in one of the two forms shown above) is odd. Otherwise, it has an even significand.

In this specification, the phrase “the Number value for x” where x - represents an exact real mathematical quantity (which might even be an -irrational number such as π) means a Number value chosen in the -following manner. Consider the set of all finite values of the Number + represents an exact real mathematical quantity (which might even be an +irrational number such as π) means a Number value chosen in the +following manner. Consider the set of all finite values of the Number type, with -0 removed and with two additional values added to it that are not representable in the Number type, namely 21024 (which is +1 × 253 × 2971) and -21024 (which is -1 × 253 × 2971). Choose the member of this set that is closest in value to x. - If two values of the set are equally close, then the one with an even + If two values of the set are equally close, then the one with an even significand is chosen; for this purpose, the two extra values 21024 and -21024 are considered to have even significands. Finally, if 21024 was chosen, replace it with +∞; if -21024 was chosen, replace it with -∞; if +0 was chosen, replace it with -0 if and only if x is less than zero; any other chosen value is used unchanged. The result is the Number value for x. (This procedure corresponds exactly to the behaviour of the IEEE 754-2008 “round to nearest, ties to even” mode.)

Some ECMAScript operators deal only with integers in specific ranges such as -231 through 231 - 1, inclusive, or in the range 0 through 216 - 1, - inclusive. These operators accept any value of the Number type but + inclusive. These operators accept any value of the Number type but first convert each such value to an integer value in the expected range. See the descriptions of the numeric conversion operations in 7.1.

@@ -1619,30 +1619,30 @@ first convert each such value to an integer value in the expected range.
  • A data property associates a key value with an ECMAScript language value and a set of Boolean attributes. - +
  • - An accessor property associates a key value with -one or two accessor functions, and a set of Boolean attributes. The + An accessor property associates a key value with +one or two accessor functions, and a set of Boolean attributes. The accessor functions are used to store or retrieve an ECMAScript language value that is associated with the property. - +
-

Properties are identified using key values. A property key +

Properties are identified using key values. A property key value is either an ECMAScript String value or a Symbol value. All String - and Symbol values, including the empty string, are valid as property + and Symbol values, including the empty string, are valid as property keys. A property name is a property key that is a String value.

An integer index is a String-valued property key that is a canonical numeric String (see 7.1.16) and whose numeric value is either +0 or a positive integer ≤ 253 - 1. An array index is an integer index whose numeric value i is in the range +0 ≤ i < 232 - 1.

Property keys are used to access properties and their values. There are two kinds of access for properties: get and set, - corresponding to value retrieval and assignment, respectively. The + corresponding to value retrieval and assignment, respectively. The properties accessible via get and set access includes both own properties that are a direct part of an object and inherited properties - which are provided by another associated object via a property -inheritance relationship. Inherited properties may be either own or -inherited properties of the associated object. Each own property of an -object must each have a key value that is distinct from the key values + which are provided by another associated object via a property +inheritance relationship. Inherited properties may be either own or +inherited properties of the associated object. Each own property of an +object must each have a key value that is distinct from the key values of the other own properties of that object.

-

All objects are logically collections of properties, but there -are multiple forms of objects that differ in their semantics for +

All objects are logically collections of properties, but there +are multiple forms of objects that differ in their semantics for accessing and manipulating their properties. Ordinary objects are the most common form of objects and have the default object semantics. An exotic object is any form of object whose property semantics differ in any way from the default semantics.

@@ -1654,71 +1654,71 @@ accessing and manipulating their properties. Ordinar @@ -1731,82 +1731,82 @@ accessing and manipulating their properties. Ordinar
Specification Name - + [[Description]] - + Value and Purpose - +
@@asyncIterator - + "Symbol.asyncIterator" - + A method that returns the default AsyncIterator for an object. Called by the semantics of the for-await-of statement. - +
@@hasInstance - + "Symbol.hasInstance" - + A method that determines if a constructor object recognizes an object as one of the constructor's instances. Called by the semantics of the instanceof operator. - +
@@isConcatSpreadable - + "Symbol.isConcatSpreadable" - + A Boolean valued property that if true indicates that an object should be flattened to its array elements by Array.prototype.concat. - +
@@iterator - + "Symbol.iterator" - + A method that returns the default Iterator for an object. Called by the semantics of the for-of statement. - +
@@match - + "Symbol.match" - + A regular expression method that matches the regular expression against a string. Called by the String.prototype.match method. - +
@@replace - + "Symbol.replace" - + A regular expression method that replaces matched substrings of a string. Called by the String.prototype.replace method. - +
@@search - + "Symbol.search" - + - A regular expression method that returns the index + A regular expression method that returns the index within a string that matches the regular expression. Called by the String.prototype.search method. - +
@@species - + "Symbol.species" - + A function valued property that is the constructor function that is used to create derived objects. - +
@@split - + "Symbol.split" - + - A regular expression method that splits a string at the + A regular expression method that splits a string at the indices that match the regular expression. Called by the String.prototype.split method. - +
@@toPrimitive - + "Symbol.toPrimitive" - + A method that converts an object to a corresponding primitive value. Called by the ToPrimitive abstract operation. - +
@@toStringTag - + "Symbol.toStringTag" - + A String valued property that is used in the creation of - the default string description of an object. Accessed by the built-in + the default string description of an object. Accessed by the built-in method Object.prototype.toString. - +
@@unscopables - + "Symbol.unscopables" - + An object valued property whose own and inherited property names are property names that are excluded from the with environment bindings of the associated object. - +
Attribute Name - + Value Domain - + Description - +
[[Value]] - + Any ECMAScript language type - + The value retrieved by a get access of the property. - +
[[Writable]] - + Boolean - + If false, attempts by ECMAScript code to change the property's [[Value]] attribute using [[Set]] will not succeed. - +
[[Enumerable]] - + Boolean - + If true, the property will be enumerated by a for-in enumeration (see 13.7.5). Otherwise, the property is said to be non-enumerable. - +
[[Configurable]] - + Boolean - + If false, attempts to delete the property, change the property to be an accessor property, or change its attributes (other than [[Value]], or changing [[Writable]] to false) will fail. - +
Attribute Name - + Value Domain - + Description - +
[[Get]] - + Object | Undefined - + If the value is an Object it must be a function object. The function's [[Call]] internal method (Table 6) is called with an empty arguments list to retrieve the property value each time a get access of the property is performed. - +
[[Set]] - + Object | Undefined - + If the value is an Object it must be a function object. The function's [[Call]] internal method (Table 6) - is called with an arguments list containing the assigned value as its -sole argument each time a set access of the property is performed. The -effect of a property's [[Set]] internal method may, but is not required -to, have an effect on the value returned by subsequent calls to the + is called with an arguments list containing the assigned value as its +sole argument each time a set access of the property is performed. The +effect of a property's [[Set]] internal method may, but is not required +to, have an effect on the value returned by subsequent calls to the property's [[Get]] internal method. - +
[[Enumerable]] - + Boolean - + If true, the property is to be enumerated by a for-in enumeration (see 13.7.5). Otherwise, the property is said to be non-enumerable. - +
[[Configurable]] - + Boolean - + If false, attempts to delete the property, change the property to be a data property, or change its attributes will fail. - +
-

If the initial values of a property's attributes are not +

If the initial values of a property's attributes are not explicitly specified by this specification, the default value defined in Table 4 is used.

Table 4: Default Attribute Values
@@ -1815,71 +1815,71 @@ explicitly specified by this specification, the default value defined in Attribute Name - + Default Value - + [[Value]] - + undefined - + [[Get]] - + undefined - + [[Set]] - + undefined - + [[Writable]] - + false - + [[Enumerable]] - + false - + [[Configurable]] - + false - + @@ -1890,47 +1890,47 @@ explicitly specified by this specification, the default value defined in

6.1.7.2Object Internal Methods and Internal Slots

The actual semantics of objects, in ECMAScript, are specified via algorithms called internal methods. - Each object in an ECMAScript engine is associated with a set of -internal methods that defines its runtime behaviour. These internal -methods are not part of the ECMAScript language. They are defined by -this specification purely for expository purposes. However, each object -within an implementation of ECMAScript must behave as specified by the -internal methods associated with it. The exact manner in which this is + Each object in an ECMAScript engine is associated with a set of +internal methods that defines its runtime behaviour. These internal +methods are not part of the ECMAScript language. They are defined by +this specification purely for expository purposes. However, each object +within an implementation of ECMAScript must behave as specified by the +internal methods associated with it. The exact manner in which this is accomplished is determined by the implementation.

-

Internal method names are polymorphic. This means that -different object values may perform different algorithms when a common +

Internal method names are polymorphic. This means that +different object values may perform different algorithms when a common internal method name is invoked upon them. That actual object upon which an internal method is invoked is the “target” of the invocation. If, at runtime, the implementation of an algorithm attempts to use an internal method of an object that the object does not support, a TypeError exception is thrown.

-

Internal slots correspond to internal state that is -associated with objects and used by various ECMAScript specification -algorithms. Internal slots are not object properties and they are not +

Internal slots correspond to internal state that is +associated with objects and used by various ECMAScript specification +algorithms. Internal slots are not object properties and they are not inherited. Depending upon the specific internal slot specification, such state may consist of values of any ECMAScript language type - or of specific ECMAScript specification type values. Unless explicitly + or of specific ECMAScript specification type values. Unless explicitly specified otherwise, internal slots are allocated as part of the process - of creating an object and may not be dynamically added to an object. + of creating an object and may not be dynamically added to an object. Unless specified otherwise, the initial value of an internal slot is the - value undefined. Various algorithms within this -specification create objects that have internal slots. However, the -ECMAScript language provides no direct way to associate internal slots + value undefined. Various algorithms within this +specification create objects that have internal slots. However, the +ECMAScript language provides no direct way to associate internal slots with an object.

-

Internal methods and internal slots are identified within +

Internal methods and internal slots are identified within this specification using names enclosed in double square brackets [[ ]].

Table 5 summarizes the essential internal methods - used by this specification that are applicable to all objects created + used by this specification that are applicable to all objects created or manipulated by ECMAScript code. Every object must have algorithms for - all of the essential internal methods. However, all objects do not + all of the essential internal methods. However, all objects do not necessarily use the same algorithms for those methods.

The “Signature” column of Table 5 - and other similar tables describes the invocation pattern for each -internal method. The invocation pattern always includes a parenthesized -list of descriptive parameter names. If a parameter name is the same as + and other similar tables describes the invocation pattern for each +internal method. The invocation pattern always includes a parenthesized +list of descriptive parameter names. If a parameter name is the same as an ECMAScript type name then the name describes the required type of the - parameter value. If an internal method explicitly returns a value, its -parameter list is followed by the symbol “→” and the type name of the -returned value. The type names used in signatures refer to the types + parameter value. If an internal method explicitly returns a value, its +parameter list is followed by the symbol “→” and the type name of the +returned value. The type names used in signatures refer to the types defined in clause 6 augmented by the following additional names. “any” means the value may be any ECMAScript language type. An internal method implicitly returns a Completion Record. In addition to its parameters, an internal method always has access to the object that is the target of the method invocation.

Table 5: Essential Internal Methods
@@ -1938,176 +1938,176 @@ defined in clause Property Descriptor - +
Return a Property Descriptor for the own property of this object whose key is propertyKey, or undefined if no such property exists. - +
[[DefineOwnProperty]] - + (propertyKey, PropertyDescriptor) → Boolean - + Create or alter the own property, whose key is propertyKey, to have the state described by PropertyDescriptor. Return true if that property was successfully created/updated or false if the property could not be created or updated. - +
[[HasProperty]] - + (propertyKey) → Boolean - + - Return a Boolean value indicating whether this object + Return a Boolean value indicating whether this object already has either an own or inherited property whose key is propertyKey. - +
[[Get]] - + (propertyKey, Receiver) → any Return the value of the property whose key is propertyKey from this object. If any ECMAScript code must be executed to retrieve the property value, Receiver is used as the this value when evaluating the code. - +
[[Set]] - + (propertyKey, value, Receiver) → Boolean - + Set the value of the property whose key is propertyKey to value. If any ECMAScript code must be executed to set the property value, Receiver is used as the this value when evaluating the code. Returns true if the property value was set or false if it could not be set. - +
[[Delete]] - + (propertyKey) → Boolean - + Remove the own property whose key is propertyKey from this object. Return false if the property was not deleted and is still present. Return true if the property was deleted or is not present. - +
[[OwnPropertyKeys]] - + ( ) → List of propertyKey - + Return a List whose elements are all of the own property keys for the object. - +

Table 6 summarizes additional essential internal methods that are supported by objects that may be called as functions. A function object is an object that supports the [[Call]] internal method. A constructor - is an object that supports the [[Construct]] internal method. Every + is an object that supports the [[Construct]] internal method. Every object that supports [[Construct]] must support [[Call]]; that is, every constructor must be a function object. Therefore, a constructor may also be referred to as a constructor function or constructor function object.

Table 6: Additional Essential Internal Methods of Function Objects
@@ -2116,21 +2116,21 @@ object that supports [[Construct]] must support [[Call]]; that is, every Internal Method - + Signature - + Description - + [[Call]] - + (any, a List of any) → any @@ -2138,26 +2138,26 @@ object that supports [[Construct]] must support [[Call]]; that is, every Executes code associated with this object. Invoked via a function call expression. The arguments to the internal method are a this - value and a list containing the arguments passed to the function by a + value and a list containing the arguments passed to the function by a call expression. Objects that implement this internal method are callable. - + [[Construct]] - + (a List of any, Object) → Object - + Creates an object. Invoked via the new or super - operators. The first argument to the internal method is a list -containing the arguments of the operator. The second argument is the + operators. The first argument to the internal method is a list +containing the arguments of the operator. The second argument is the object to which the new operator was initially applied. Objects that implement this internal method are called constructors. A function object is not necessarily a constructor and such non-constructor function objects do not have a [[Construct]] internal method. - + @@ -2168,119 +2168,119 @@ object to which the new operator was initially applied. Objects tha

6.1.7.3Invariants of the Essential Internal Methods

-

The Internal Methods of Objects of an ECMAScript engine must -conform to the list of invariants specified below. Ordinary ECMAScript -Objects as well as all standard exotic objects in this specification -maintain these invariants. ECMAScript Proxy objects maintain these -invariants by means of runtime checks on the result of traps invoked on +

The Internal Methods of Objects of an ECMAScript engine must +conform to the list of invariants specified below. Ordinary ECMAScript +Objects as well as all standard exotic objects in this specification +maintain these invariants. ECMAScript Proxy objects maintain these +invariants by means of runtime checks on the result of traps invoked on the [[ProxyHandler]] object.

Any implementation provided exotic objects must also maintain - these invariants for those objects. Violation of these invariants may -cause ECMAScript code to have unpredictable behaviour and create -security issues. However, violation of these invariants must never + these invariants for those objects. Violation of these invariants may +cause ECMAScript code to have unpredictable behaviour and create +security issues. However, violation of these invariants must never compromise the memory safety of an implementation.

-

An implementation must not allow these invariants to be -circumvented in any manner such as by providing alternative interfaces -that implement the functionality of the essential internal methods +

An implementation must not allow these invariants to be +circumvented in any manner such as by providing alternative interfaces +that implement the functionality of the essential internal methods without enforcing their invariants.

Definitions:

  • The target of an internal method is the object upon which the internal method is called. - +
  • A target is non-extensible if it has been observed to return false from its [[IsExtensible]] internal method, or true from its [[PreventExtensions]] internal method. - +
  • A non-existent property is a property that does not exist as an own property on a non-extensible target. - +
  • All references to SameValue are according to the definition of the SameValue algorithm. - +

[[GetPrototypeOf]] ( )

  • The Type of the return value must be either Object or Null. - +
  • If target is non-extensible, and [[GetPrototypeOf]] returns a value V, then any future calls to [[GetPrototypeOf]] should return the SameValue as V. - +
Note 1

An object's prototype chain should have finite length (that - is, starting from any object, recursively applying the -[[GetPrototypeOf]] internal method to its result should eventually lead -to the value null). However, this requirement is not + is, starting from any object, recursively applying the +[[GetPrototypeOf]] internal method to its result should eventually lead +to the value null). However, this requirement is not enforceable as an object level invariant if the prototype chain includes - any exotic objects that do not use the ordinary object definition of -[[GetPrototypeOf]]. Such a circular prototype chain may result in + any exotic objects that do not use the ordinary object definition of +[[GetPrototypeOf]]. Such a circular prototype chain may result in infinite loops when accessing object properties.

[[SetPrototypeOf]] ( V )

  • The Type of the return value must be Boolean. - +
  • If target is non-extensible, [[SetPrototypeOf]] must return false, unless V is the SameValue as the target's observed [[GetPrototypeOf]] value. - +

[[IsExtensible]] ( )

  • The Type of the return value must be Boolean. - +
  • If [[IsExtensible]] returns false, all future calls to [[IsExtensible]] on the target must return false. - +

[[PreventExtensions]] ( )

  • The Type of the return value must be Boolean. - +
  • If [[PreventExtensions]] returns true, all future calls to [[IsExtensible]] on the target must return false and the target is now considered non-extensible. - +

[[GetOwnProperty]] ( P )

  • The Type of the return value must be either Property Descriptor or Undefined. - +
  • If the Type of the return value is Property Descriptor, the return value must be a complete property descriptor. - +
  • If P is described as a non-configurable, non-writable own data property, all future calls to [[GetOwnProperty]] ( P ) must return Property Descritor whose [[Value]] is SameValue as P's [[Value]] attribute. - +
  • If P's attributes other than [[Writable]] may change over time or if the property might be deleted, then P's [[Configurable]] attribute must be true. - +
  • If the [[Writable]] attribute may change from false to true, then the [[Configurable]] attribute must be true. - +
  • If the target is non-extensible and P is non-existent, then all future calls to [[GetOwnProperty]] (P) on the target must describe P as non-existent (i.e. [[GetOwnProperty]] (P) must return undefined). - +
Note 2
@@ -2290,113 +2290,113 @@ infinite loops when accessing object properties.

  • The Type of the return value must be Boolean. - +
  • [[DefineOwnProperty]] must return false if P has previously been observed as a non-configurable own property of the target, unless either: - +
    1. P is a writable data property. A non-configurable writable data property can be changed into a non-configurable non-writable data property. - +
    2. All attributes of Desc are the SameValue as P's attributes. - +
  • [[DefineOwnProperty]] (P, Desc) must return false if target is non-extensible and P is a non-existent own property. That is, a non-extensible target object cannot be extended with new properties. - +

[[HasProperty]] ( P )

  • The Type of the return value must be Boolean. - +
  • If P was previously observed as a non-configurable own data or accessor property of the target, [[HasProperty]] must return true. - +

[[Get]] ( P, Receiver )

  • If P was previously observed as a non-configurable, non-writable own data property of the target with value V, then [[Get]] must return the SameValue as V. - +
  • If P was previously observed as a non-configurable own accessor property of the target whose [[Get]] attribute is undefined, the [[Get]] operation must return undefined. - +

[[Set]] ( P, V, Receiver )

  • The Type of the return value must be Boolean. - +
  • If P was previously observed as a non-configurable, non-writable own data property of the target, then [[Set]] must return false unless V is the SameValue as P's [[Value]] attribute. - +
  • If P was previously observed as a non-configurable own accessor property of the target whose [[Set]] attribute is undefined, the [[Set]] operation must return false. - +

[[Delete]] ( P )

  • The Type of the return value must be Boolean. - +
  • If P was previously observed as a non-configurable own data or accessor property of the target, [[Delete]] must return false. - +

[[OwnPropertyKeys]] ( )

  • The return value must be a List. - +
  • The returned List must not contain any duplicate entries. - +
  • The Type of each element of the returned List is either String or Symbol. - +
  • The returned List must contain at least the keys of all non-configurable own properties that have previously been observed. - +
  • If the object is non-extensible, the returned List must contain only the keys of all own properties of the object that are observable using [[GetOwnProperty]]. - +

[[Construct]] ( )

  • The Type of the return value must be Object. - +

6.1.7.4Well-Known Intrinsic Objects

-

Well-known intrinsics are built-in objects that are -explicitly referenced by the algorithms of this specification and which +

Well-known intrinsics are built-in objects that are +explicitly referenced by the algorithms of this specification and which usually have realm-specific - identities. Unless otherwise specified each intrinsic object actually + identities. Unless otherwise specified each intrinsic object actually corresponds to a set of similar objects, one per realm.

Within this specification a reference such as %name% means the intrinsic object, associated with the current realm, corresponding to the name. Determination of the current realm and its intrinsics is described in 8.3. The well-known intrinsics are listed in Table 7.

Table 7: Well-Known Intrinsic Objects
@@ -2405,1519 +2405,1519 @@ corresponds to a set of similar objects, one per %Array% - + Array - + The Array constructor (22.1.1) - + %ArrayBuffer% - + ArrayBuffer - + The ArrayBuffer constructor (24.1.2) - + %ArrayBufferPrototype% - + ArrayBuffer.prototype - + The initial value of the prototype data property of %ArrayBuffer%. - + %ArrayIteratorPrototype% - + The prototype of Array iterator objects (22.1.5) - + %ArrayPrototype% - + Array.prototype - + The initial value of the prototype data property of %Array% (22.1.3) - + %ArrayProto_entries% - + Array.prototype.entries - + The initial value of the entries data property of %ArrayPrototype% (22.1.3.4) - + %ArrayProto_forEach% - + Array.prototype.forEach - + The initial value of the forEach data property of %ArrayPrototype% (22.1.3.12) - + %ArrayProto_keys% - + Array.prototype.keys - + The initial value of the keys data property of %ArrayPrototype% (22.1.3.16) - + %ArrayProto_values% - + Array.prototype.values - + The initial value of the values data property of %ArrayPrototype% (22.1.3.32) - + %AsyncFromSyncIteratorPrototype% - + The prototype of async-from-sync iterator objects (25.1.4) - + %AsyncFunction% - + The constructor of async function objects (25.7.1) - + %AsyncFunctionPrototype% - + The initial value of the prototype data property of %AsyncFunction% - + %AsyncGenerator% - + The initial value of the prototype property of %AsyncGeneratorFunction% - + %AsyncGeneratorFunction% - + The constructor of async iterator objects (25.3.1) - + %AsyncGeneratorPrototype% - + The initial value of the prototype property of %AsyncGenerator% - + %AsyncIteratorPrototype% - + An object that all standard built-in async iterator objects indirectly inherit from - + %Atomics% - + Atomics - + The Atomics object (24.4) - + %Boolean% - + Boolean - + The Boolean constructor (19.3.1) - + %BooleanPrototype% - + Boolean.prototype - + The initial value of the prototype data property of %Boolean% (19.3.3) - + %DataView% - + DataView - + The DataView constructor (24.3.2) - + %DataViewPrototype% - + DataView.prototype - + The initial value of the prototype data property of %DataView% - + %Date% - + Date - + The Date constructor (20.3.2) - + %DatePrototype% - + Date.prototype - + The initial value of the prototype data property of %Date%. - + %decodeURI% - + decodeURI - + The decodeURI function (18.2.6.2) - + %decodeURIComponent% - + decodeURIComponent - + The decodeURIComponent function (18.2.6.3) - + %encodeURI% - + encodeURI - + The encodeURI function (18.2.6.4) - + %encodeURIComponent% - + encodeURIComponent - + The encodeURIComponent function (18.2.6.5) - + %Error% - + Error - + The Error constructor (19.5.1) - + %ErrorPrototype% - + Error.prototype - + The initial value of the prototype data property of %Error% - + %eval% - + eval - + The eval function (18.2.1) - + %EvalError% - + EvalError - + The EvalError constructor (19.5.5.1) - + %EvalErrorPrototype% - + EvalError.prototype - + The initial value of the prototype data property of %EvalError% - + %Float32Array% - + Float32Array - + The Float32Array constructor (22.2) - + %Float32ArrayPrototype% - + Float32Array.prototype - + The initial value of the prototype data property of %Float32Array% - + %Float64Array% - + Float64Array - + The Float64Array constructor (22.2) - + %Float64ArrayPrototype% - + Float64Array.prototype - + The initial value of the prototype data property of %Float64Array% - + %Function% - + Function - + The Function constructor (19.2.1) - + %FunctionPrototype% - + Function.prototype - + The initial value of the prototype data property of %Function% - + %Generator% - + The initial value of the prototype data property of %GeneratorFunction% - + %GeneratorFunction% - + The constructor of generator objects (25.2.1) - + %GeneratorPrototype% - + The initial value of the prototype data property of %Generator% - + %Int8Array% - + Int8Array - + The Int8Array constructor (22.2) - + %Int8ArrayPrototype% - + Int8Array.prototype - + The initial value of the prototype data property of %Int8Array% - + %Int16Array% - + Int16Array - + The Int16Array constructor (22.2) - + %Int16ArrayPrototype% - + Int16Array.prototype - + The initial value of the prototype data property of %Int16Array% - + %Int32Array% - + Int32Array - + The Int32Array constructor (22.2) - + %Int32ArrayPrototype% - + Int32Array.prototype - + The initial value of the prototype data property of %Int32Array% - + %isFinite% - + isFinite - + The isFinite function (18.2.2) - + %isNaN% - + isNaN - + The isNaN function (18.2.3) - + %IteratorPrototype% - + An object that all standard built-in iterator objects indirectly inherit from - + %JSON% - + JSON - + The JSON object (24.5) - + %JSONParse% - + JSON.parse - + The initial value of the parse data property of %JSON% - + %JSONStringify% - + JSON.stringify - + The initial value of the stringify data property of %JSON% - + %Map% - + Map - + The Map constructor (23.1.1) - + %MapIteratorPrototype% - + The prototype of Map iterator objects (23.1.5) - + %MapPrototype% - + Map.prototype - + The initial value of the prototype data property of %Map% - + %Math% - + Math - + The Math object (20.2) - + %Number% - + Number - + The Number constructor (20.1.1) - + %NumberPrototype% - + Number.prototype - + The initial value of the prototype data property of %Number% - + %Object% - + Object - + The Object constructor (19.1.1) - + %ObjectPrototype% - + Object.prototype - + The initial value of the prototype data property of %Object% (19.1.3) - + %ObjProto_toString% - + Object.prototype.toString - + The initial value of the toString data property of %ObjectPrototype% (19.1.3.6) - + %ObjProto_valueOf% - + Object.prototype.valueOf - + The initial value of the valueOf data property of %ObjectPrototype% (19.1.3.7) - + %parseFloat% - + parseFloat - + The parseFloat function (18.2.4) - + %parseInt% - + parseInt - + The parseInt function (18.2.5) - + %Promise% - + Promise - + The Promise constructor (25.6.3) - + %PromisePrototype% - + Promise.prototype - + The initial value of the prototype data property of %Promise% - + %PromiseProto_then% - + Promise.prototype.then - + The initial value of the then data property of %PromisePrototype% (25.6.5.4) - + %Promise_all% - + Promise.all - + The initial value of the all data property of %Promise% (25.6.4.1) - + %Promise_reject% - + Promise.reject - + The initial value of the reject data property of %Promise% (25.6.4.4) - + %Promise_resolve% - + Promise.resolve - + The initial value of the resolve data property of %Promise% (25.6.4.5) - + %Proxy% - + Proxy - + The Proxy constructor (26.2.1) - + %RangeError% - + RangeError - + The RangeError constructor (19.5.5.2) - + %RangeErrorPrototype% - + RangeError.prototype - + The initial value of the prototype data property of %RangeError% - + %ReferenceError% - + ReferenceError - + The ReferenceError constructor (19.5.5.3) - + %ReferenceErrorPrototype% - + ReferenceError.prototype - + The initial value of the prototype data property of %ReferenceError% - + %Reflect% - + Reflect - + The Reflect object (26.1) - + %RegExp% - + RegExp - + The RegExp constructor (21.2.3) - + %RegExpPrototype% - + RegExp.prototype - + The initial value of the prototype data property of %RegExp% - + %Set% - + Set - + The Set constructor (23.2.1) - + %SetIteratorPrototype% - + The prototype of Set iterator objects (23.2.5) - + %SetPrototype% - + Set.prototype - + The initial value of the prototype data property of %Set% - + %SharedArrayBuffer% - + SharedArrayBuffer - + The SharedArrayBuffer constructor (24.2.2) - + %SharedArrayBufferPrototype% - + SharedArrayBuffer.prototype - + The initial value of the prototype data property of %SharedArrayBuffer% - + %String% - + String - + The String constructor (21.1.1) - + %StringIteratorPrototype% - + The prototype of String iterator objects (21.1.5) - + %StringPrototype% - + String.prototype - + The initial value of the prototype data property of %String% - + %Symbol% - + Symbol - + The Symbol constructor (19.4.1) - + %SymbolPrototype% - + Symbol.prototype - + The initial value of the prototype data property of %Symbol% (19.4.3) - + %SyntaxError% - + SyntaxError - + The SyntaxError constructor (19.5.5.4) - + %SyntaxErrorPrototype% - + SyntaxError.prototype - + The initial value of the prototype data property of %SyntaxError% - + %ThrowTypeError% - + A function object that unconditionally throws a new instance of %TypeError% - + %TypedArray% - + The super class of all typed Array constructors (22.2.1) - + %TypedArrayPrototype% - + The initial value of the prototype data property of %TypedArray% - + %TypeError% - + TypeError - + The TypeError constructor (19.5.5.5) - + %TypeErrorPrototype% - + TypeError.prototype - + The initial value of the prototype data property of %TypeError% - + %Uint8Array% - + Uint8Array - + The Uint8Array constructor (22.2) - + %Uint8ArrayPrototype% - + Uint8Array.prototype - + The initial value of the prototype data property of %Uint8Array% - + %Uint8ClampedArray% - + Uint8ClampedArray - + The Uint8ClampedArray constructor (22.2) - + %Uint8ClampedArrayPrototype% - + Uint8ClampedArray.prototype - + The initial value of the prototype data property of %Uint8ClampedArray% - + %Uint16Array% - + Uint16Array - + The Uint16Array constructor (22.2) - + %Uint16ArrayPrototype% - + Uint16Array.prototype - + The initial value of the prototype data property of %Uint16Array% - + %Uint32Array% - + Uint32Array - + The Uint32Array constructor (22.2) - + %Uint32ArrayPrototype% - + Uint32Array.prototype - + The initial value of the prototype data property of %Uint32Array% - + %URIError% - + URIError - + The URIError constructor (19.5.5.6) - + %URIErrorPrototype% - + URIError.prototype - + The initial value of the prototype data property of %URIError% - + %WeakMap% - + WeakMap - + The WeakMap constructor (23.3.1) - + %WeakMapPrototype% - + WeakMap.prototype - + The initial value of the prototype data property of %WeakMap% - + %WeakSet% - + WeakSet - + The WeakSet constructor (23.4.1) - + %WeakSetPrototype% - + WeakSet.prototype - + The initial value of the prototype data property of %WeakSet% - + @@ -3929,62 +3929,62 @@ corresponds to a set of similar objects, one per

6.2ECMAScript Specification Types

-

A specification type corresponds to meta-values that are used -within algorithms to describe the semantics of ECMAScript language -constructs and ECMAScript language types. The specification types +

A specification type corresponds to meta-values that are used +within algorithms to describe the semantics of ECMAScript language +constructs and ECMAScript language types. The specification types include Reference, List, Completion, Property Descriptor, Lexical Environment, Environment Record, and Data Block. - Specification type values are specification artefacts that do not -necessarily correspond to any specific entity within an ECMAScript -implementation. Specification type values may be used to describe + Specification type values are specification artefacts that do not +necessarily correspond to any specific entity within an ECMAScript +implementation. Specification type values may be used to describe intermediate results of ECMAScript expression evaluation but such values - cannot be stored as properties of objects or values of ECMAScript + cannot be stored as properties of objects or values of ECMAScript language variables.

6.2.1The List and Record Specification Types

The List type is used to explain the evaluation of argument lists (see 12.3.6) in new - expressions, in function calls, and in other algorithms where a simple -ordered list of values is needed. Values of the List type are simply -ordered sequences of list elements containing the individual values. -These sequences may be of any length. The elements of a list may be -randomly accessed using 0-origin indices. For notational convenience an + expressions, in function calls, and in other algorithms where a simple +ordered list of values is needed. Values of the List type are simply +ordered sequences of list elements containing the individual values. +These sequences may be of any length. The elements of a list may be +randomly accessed using 0-origin indices. For notational convenience an array-like syntax can be used to access List elements. For example, arguments[2] is shorthand for saying the 3rd element of the List arguments.

For notational convenience within this specification, a literal - syntax can be used to express a new List value. For example, « 1, 2 » -defines a List value that has two elements each of which is initialized + syntax can be used to express a new List value. For example, « 1, 2 » +defines a List value that has two elements each of which is initialized to a specific value. A new empty List can be expressed as « ».

-

The Record type is used to describe data -aggregations within the algorithms of this specification. A Record type -value consists of one or more named fields. The value of each field is -either an ECMAScript value or an abstract value represented by a name -associated with the Record type. Field names are always enclosed in +

The Record type is used to describe data +aggregations within the algorithms of this specification. A Record type +value consists of one or more named fields. The value of each field is +either an ECMAScript value or an abstract value represented by a name +associated with the Record type. Field names are always enclosed in double brackets, for example [[Value]].

For notational convenience within this specification, an object literal-like syntax can be used to express a Record value. For example, { [[Field1]]: 42, [[Field2]]: false, [[Field3]]: empty - } defines a Record value that has three fields, each of which is -initialized to a specific value. Field name order is not significant. + } defines a Record value that has three fields, each of which is +initialized to a specific value. Field name order is not significant. Any fields that are not explicitly listed are considered to be absent.

-

In specification text and algorithms, dot notation may be used +

In specification text and algorithms, dot notation may be used to refer to a specific field of a Record value. For example, if R is the - record shown in the previous paragraph then R.[[Field2]] is shorthand + record shown in the previous paragraph then R.[[Field2]] is shorthand for “the field of R named [[Field2]]”.

-

Schema for commonly used Record field combinations may be -named, and that name may be used as a prefix to a literal Record value -to identify the specific kind of aggregations that is being described. +

Schema for commonly used Record field combinations may be +named, and that name may be used as a prefix to a literal Record value +to identify the specific kind of aggregations that is being described. For example: PropertyDescriptor { [[Value]]: 42, [[Writable]]: false, [[Configurable]]: true }.

6.2.2The Set and Relation Specification Types

The Set type is used to explain a collection of unordered elements for use in the memory model. - Values of the Set type are simple collections of elements, where no -element appears more than once. Elements may be added to and removed -from Sets. Sets may be unioned, intersected, or subtracted from each + Values of the Set type are simple collections of elements, where no +element appears more than once. Elements may be added to and removed +from Sets. Sets may be unioned, intersected, or subtracted from each other.

The Relation type is used to explain constraints on - Sets. Values of the Relation type are Sets of ordered pairs of values -from its value domain. For example, a Relation on events is a set of + Sets. Values of the Relation type are Sets of ordered pairs of values +from its value domain. For example, a Relation on events is a set of ordered pairs of events. For a Relation R and two values a and b in the value domain of R, a R b is shorthand for saying the ordered pair (a, b) is a member of R. A Relation is least with respect to some conditions when it is the smallest Relation that satisfies those conditions.

A strict partial order is a Relation value R that satisfies the following.

    @@ -4025,57 +4025,57 @@ ordered pairs of events. For a Relation R and two values a Field Name - + Value - + Meaning - + [[Type]] - + One of normal, break, continue, return, or throw - + The type of completion that occurred. - + [[Value]] - + any ECMAScript language value or empty - + The value that was produced. - + [[Target]] - + any ECMAScript string or empty - + The target label for directed control transfers. - + @@ -4172,7 +4172,7 @@ ordered pairs of events. For a Relation R and two values a

A Reference is a resolved name or property binding. A Reference consists of three components, the base value component, the - referenced name component, and the Boolean-valued strict reference + referenced name component, and the Boolean-valued strict reference flag. The base value component is either undefined, an Object, a Boolean, a String, a Symbol, a Number, or an Environment Record. A base value component of undefined indicates that the Reference could not be resolved to a binding. The referenced name component is a String or Symbol value.

A Super Reference is a Reference that is used to represent a name binding that was expressed using the super keyword. A Super Reference has an additional thisValue component, and its base value component will never be an Environment Record.

The following abstract operations are used in this specification to operate on references:

@@ -4224,9 +4224,9 @@ flag. The base value component is either undefined, an Object
  1. ReturnIfAbrupt(V).
  2. If Type(V) is not Reference, return V.
  3. Let base be GetBase(V).
  4. If IsUnresolvableReference(V) is true, throw a ReferenceError exception.
  5. If IsPropertyReference(V) is true, then
    1. If HasPrimitiveBase(V) is true, then
      1. Assert: In this case, base will never be undefined or null.
      2. Set base to ! ToObject(base).
    2. Return ? base.[[Get]](GetReferencedName(V), GetThisValue(V)).
  6. Else base must be an Environment Record,
    1. Return ? base.GetBindingValue(GetReferencedName(V), IsStrictReference(V)) (see 8.1.1).
Note
-

The object that may be created in step 5.a.ii is not -accessible outside of the above abstract operation and the ordinary -object [[Get]] internal method. An implementation might choose to avoid +

The object that may be created in step 5.a.ii is not +accessible outside of the above abstract operation and the ordinary +object [[Get]] internal method. An implementation might choose to avoid the actual creation of the object.

 @@ -4236,9 +4236,9 @@ the actual creation of the object.

  1. ReturnIfAbrupt(V).
  2. ReturnIfAbrupt(W).
  3. If Type(V) is not Reference, throw a ReferenceError exception.
  4. Let base be GetBase(V).
  5. If IsUnresolvableReference(V) is true, then
    1. If IsStrictReference(V) is true, then
      1. Throw a ReferenceError exception.
    2. Let globalObj be GetGlobalObject().
    3. Return ? Set(globalObj, GetReferencedName(V), W, false).
  6. Else if IsPropertyReference(V) is true, then
    1. If HasPrimitiveBase(V) is true, then
      1. Assert: In this case, base will never be undefined or null.
      2. Set base to ! ToObject(base).
    2. Let succeeded be ? base.[[Set]](GetReferencedName(V), W, GetThisValue(V)).
    3. If succeeded is false and IsStrictReference(V) is true, throw a TypeError exception.
    4. Return.
  7. Else base must be an Environment Record,
    1. Return ? base.SetMutableBinding(GetReferencedName(V), W, IsStrictReference(V)) (see 8.1.1).
Note
-

The object that may be created in step 6.a.ii is not -accessible outside of the above algorithm and the ordinary object -[[Set]] internal method. An implementation might choose to avoid the +

The object that may be created in step 6.a.ii is not +accessible outside of the above algorithm and the ordinary object +[[Set]] internal method. An implementation might choose to avoid the actual creation of that object.

 @@ -4259,26 +4259,26 @@ actual creation of that object.

6.2.5The Property Descriptor Specification Type

The Property Descriptor type is used to explain the - manipulation and reification of Object property attributes. Values of -the Property Descriptor type are Records. Each field's name is an -attribute name and its value is a corresponding attribute value as + manipulation and reification of Object property attributes. Values of +the Property Descriptor type are Records. Each field's name is an +attribute name and its value is a corresponding attribute value as specified in 6.1.7.1. - In addition, any field may be present or absent. The schema name used -within this specification to tag literal descriptions of Property + In addition, any field may be present or absent. The schema name used +within this specification to tag literal descriptions of Property Descriptor records is “PropertyDescriptor”.

-

Property Descriptor values may be further classified as data -Property Descriptors and accessor Property Descriptors based upon the -existence or use of certain fields. A data Property Descriptor is one -that includes any fields named either [[Value]] or [[Writable]]. An -accessor Property Descriptor is one that includes any fields named +

Property Descriptor values may be further classified as data +Property Descriptors and accessor Property Descriptors based upon the +existence or use of certain fields. A data Property Descriptor is one +that includes any fields named either [[Value]] or [[Writable]]. An +accessor Property Descriptor is one that includes any fields named either [[Get]] or [[Set]]. Any Property Descriptor may have fields named - [[Enumerable]] and [[Configurable]]. A Property Descriptor value may -not be both a data Property Descriptor and an accessor Property + [[Enumerable]] and [[Configurable]]. A Property Descriptor value may +not be both a data Property Descriptor and an accessor Property Descriptor; however, it may be neither. A generic Property Descriptor is - a Property Descriptor value that is neither a data Property Descriptor -nor an accessor Property Descriptor. A fully populated Property -Descriptor is one that is either an accessor Property Descriptor or a -data Property Descriptor and that has all of the fields that correspond + a Property Descriptor value that is neither a data Property Descriptor +nor an accessor Property Descriptor. A fully populated Property +Descriptor is one that is either an accessor Property Descriptor or a +data Property Descriptor and that has all of the fields that correspond to the property attributes defined in either Table 2 or Table 3.

The following abstract operations are used in this specification to operate upon Property Descriptor values:

@@ -4328,27 +4328,27 @@ to the property attributes defined in either

6.2.6The Lexical Environment and Environment Record Specification Types

The Lexical Environment and Environment Record - types are used to explain the behaviour of name resolution in nested -functions and blocks. These types and the operations upon them are + types are used to explain the behaviour of name resolution in nested +functions and blocks. These types and the operations upon them are defined in 8.1.

6.2.7Data Blocks

-

The Data Block specification type is used to -describe a distinct and mutable sequence of byte-sized (8 bit) numeric -values. A Data Block value is created with a fixed number of bytes that +

The Data Block specification type is used to +describe a distinct and mutable sequence of byte-sized (8 bit) numeric +values. A Data Block value is created with a fixed number of bytes that each have the initial value 0.

-

For notational convenience within this specification, an -array-like syntax can be used to access the individual bytes of a Data -Block value. This notation presents a Data Block value as a 0-origined +

For notational convenience within this specification, an +array-like syntax can be used to access the individual bytes of a Data +Block value. This notation presents a Data Block value as a 0-origined integer-indexed sequence of bytes. For example, if db is a 5 byte Data Block value then db[2] can be used to access its 3rd byte.

A data block that resides in memory that can be referenced from multiple agents concurrently is designated a Shared Data Block. A Shared Data Block has an identity (for the purposes of equality testing Shared Data Block values) that is address-free: - it is tied not to the virtual addresses the block is mapped to in any -process, but to the set of locations in memory that the block -represents. Two data blocks are equal only if the sets of the locations -they contain are equal; otherwise, they are not equal and the -intersection of the sets of locations they contain is empty. Finally, + it is tied not to the virtual addresses the block is mapped to in any +process, but to the set of locations in memory that the block +represents. Two data blocks are equal only if the sets of the locations +they contain are equal; otherwise, they are not equal and the +intersection of the sets of locations they contain is empty. Finally, Shared Data Blocks can be distinguished from Data Blocks.

The semantics of Shared Data Blocks is defined using Shared Data Block events by the memory model. Abstract operations below introduce Shared Data Block events and act as the interface between evaluation semantics and the event semantics of the memory model. The events form a candidate execution, on which the memory model acts as a filter. Please consult the memory model for full semantics.

Shared Data Block events are modeled by Records, defined in the memory model.

@@ -4372,7 +4372,7 @@ Shared Data Blocks can be distinguished from Data Blocks.

6.2.7.3CopyDataBlockBytes ( toBlock, toIndex, fromBlock, fromIndex, count )

When the abstract operation CopyDataBlockBytes is called, the following steps are taken:

  1. Assert: fromBlock and toBlock are distinct Data Block or Shared Data Block values.
  2. Assert: fromIndex, toIndex, and count are integer values ≥ 0.
  3. Let fromSize be the number of bytes in fromBlock.
  4. Assert: fromIndex + count ≤ fromSize.
  5. Let toSize be the number of bytes in toBlock.
  6. Assert: toIndex + count ≤ toSize.
  7. Repeat, while count > 0
    1. If fromBlock is a Shared Data Block, then
      1. Let execution be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
      2. Let eventList be the [[EventList]] field of the element in execution.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
      3. Let bytes be a List of length 1 that contains a nondeterministically chosen byte value.
      4. NOTE: In implementations, bytes - is the result of a non-atomic read instruction on the underlying + is the result of a non-atomic read instruction on the underlying hardware. The nondeterminism is a semantic prescription of the memory model to describe observable behaviour of hardware with weak consistency.
      5. Let readEvent be ReadSharedMemory { [[Order]]: "Unordered", [[NoTear]]: true, [[Block]]: fromBlock, [[ByteIndex]]: fromIndex, [[ElementSize]]: 1 }.
      6. Append readEvent to eventList.
      7. Append Chosen Value Record { [[Event]]: readEvent, [[ChosenValue]]: bytes } to execution.[[ChosenValues]].
      8. If toBlock is a Shared Data Block, then
        1. Append WriteSharedMemory { [[Order]]: "Unordered", [[NoTear]]: true, [[Block]]: toBlock, [[ByteIndex]]: toIndex, [[ElementSize]]: 1, [[Payload]]: bytes } to eventList.
      9. Else,
        1. Set toBlock[toIndex] to bytes[0].
    2. Else,
      1. Assert: toBlock is not a Shared Data Block.
      2. Set toBlock[toIndex] to fromBlock[fromIndex].
    3. Increment toIndex and fromIndex each by 1.
    4. Decrement count by 1.
  8. Return NormalCompletion(empty).
@@ -4382,14 +4382,14 @@ hardware. The nondeterminism is a semantic prescription of the

7Abstract Operations

-

These operations are not a part of the ECMAScript language; they -are defined here to solely to aid the specification of the semantics of +

These operations are not a part of the ECMAScript language; they +are defined here to solely to aid the specification of the semantics of the ECMAScript language. Other, more specialized abstract operations are defined throughout this specification.

7.1Type Conversion

-

The ECMAScript language implicitly performs automatic type -conversion as needed. To clarify the semantics of certain constructs it +

The ECMAScript language implicitly performs automatic type +conversion as needed. To clarify the semantics of certain constructs it is useful to define a set of conversion abstract operations. The conversion abstract operations are polymorphic; they can accept a value of any ECMAScript language type. But no other specification types are used with these operations.

@@ -4400,9 +4400,9 @@ is useful to define a set of conversion Assert: input is an ECMAScript language value.
  • If Type(input) is Object, then
    1. If PreferredType is not present, let hint be "default".
    2. Else if PreferredType is hint String, let hint be "string".
    3. Else PreferredType is hint Number, let hint be "number".
    4. Let exoticToPrim be ? GetMethod(input, @@toPrimitive).
    5. If exoticToPrim is not undefined, then
      1. Let result be ? Call(exoticToPrim, input, « hint »).
      2. If Type(result) is not Object, return result.
      3. Throw a TypeError exception.
    6. If hint is "default", set hint to "number".
    7. Return ? OrdinaryToPrimitive(input, hint).
  • Return input.
    • Note
    -

    When ToPrimitive is called with no hint, then it generally -behaves as if the hint were Number. However, objects may over-ride this -behaviour by defining a @@toPrimitive method. Of the objects defined in +

    When ToPrimitive is called with no hint, then it generally +behaves as if the hint were Number. However, objects may over-ride this +behaviour by defining a @@toPrimitive method. Of the objects defined in this specification only Date objects (see 20.3.4.45) and Symbol objects (see 19.4.3.5) over-ride the default ToPrimitive behaviour. Date objects treat no hint as if the hint were String.

     @@ -4423,81 +4423,81 @@ this specification only Date objects (see Argument Type - + Result - + Undefined - + Return NaN. - + Null - + Return +0. - + Boolean - + If argument is true, return 1. If argument is false, return +0. - + Number - + Return argument (no conversion). - + String - + See grammar and conversion algorithm below. - + Symbol - + Throw a TypeError exception. - + Object - +

    Apply the following steps:

    @@ -4600,7 +4600,7 @@ this specification only Date objects (see 7.1.3.1ToNumber Applied to the String Type

    ToNumber applied to Strings applies the following grammar to the input String interpreted as a sequence of UTF-16 encoded code points (6.1.4). If the grammar cannot interpret the String as an expansion of StringNumericLiteral, then the result of ToNumber is NaN.

    Note 1
    -

    The terminal symbols of this grammar are all composed of +

    The terminal symbols of this grammar are all composed of characters in the Unicode Basic Multilingual Plane (BMP). Therefore, the result of ToNumber will be NaN if the string contains any leading surrogate or trailing surrogate code units, whether paired or unpaired.

     @@ -4639,175 +4639,175 @@ characters in the Unicode Basic Multilingual Plane (BMP). Therefore, the

    7.1.3.1.1Runtime Semantics: MV

    -

    The conversion of a String to a Number value is similar -overall to the determination of the Number value for a numeric literal +

    The conversion of a String to a Number value is similar +overall to the determination of the Number value for a numeric literal (see 11.8.3), - but some of the details are different, so the process for converting a -String numeric literal to a value of Number type is given here. This -value is determined in two steps: first, a mathematical value (MV) is + but some of the details are different, so the process for converting a +String numeric literal to a value of Number type is given here. This +value is determined in two steps: first, a mathematical value (MV) is derived from the String numeric literal; second, this mathematical value - is rounded as described below. The MV on any grammar symbol, not + is rounded as described below. The MV on any grammar symbol, not provided below, is the MV for that symbol defined in 11.8.3.1.

    -

    Once the exact MV for a String numeric literal has been -determined, it is then rounded to a value of the Number type. If the MV +

    Once the exact MV for a String numeric literal has been +determined, it is then rounded to a value of the Number type. If the MV is 0, then the rounded value is +0 unless the first non white space code point in the String numeric literal is "-", in which case the rounded value is -0. Otherwise, the rounded value must be the Number value for the MV (in the sense defined in 6.1.6), unless the literal includes a StrUnsignedDecimalLiteral - and the literal has more than 20 significant digits, in which case the -Number value may be either the Number value for the MV of a literal -produced by replacing each significant digit after the 20th with a 0 -digit or the Number value for the MV of a literal produced by replacing -each significant digit after the 20th with a 0 digit and then -incrementing the literal at the 20th digit position. A digit is + and the literal has more than 20 significant digits, in which case the +Number value may be either the Number value for the MV of a literal +produced by replacing each significant digit after the 20th with a 0 +digit or the Number value for the MV of a literal produced by replacing +each significant digit after the 20th with a 0 digit and then +incrementing the literal at the 20th digit position. A digit is significant if it is not part of an ExponentPart and

    • it is not 0; or - +
    • there is a nonzero digit to its left and there is a nonzero digit, not in the ExponentPart, to its right. - +
    @@ -4831,17 +4831,17 @@ significant if it is not part of an ToUint32    (x)) is equal to ToInt32(x) for all values of x. (It is to preserve this latter property that +∞ and -∞ are mapped to +0.) - +
  • ToInt32 maps -0 to +0. - +
    • @@ -4857,21 +4857,21 @@ unchanged.
    • Step 5 is the only difference between ToUint32 and ToInt32. - +
    • The ToUint32 abstract operation is idempotent: if applied to - a result that it produced, the second application leaves that value + a result that it produced, the second application leaves that value unchanged. - +
    • ToUint32(ToInt32(x)) is equal to ToUint32(x) for all values of x. (It is to preserve this latter property that +∞ and -∞ are mapped to +0.) - +
    • ToUint32 maps -0 to +0. - +
    @@ -4894,11 +4894,11 @@ unchanged.
    • The substitution of 216 for 232 in step 4 is the only difference between ToUint32 and ToUint16. - +
    • ToUint16 maps -0 to +0. - +
    @@ -4924,8 +4924,8 @@ unchanged.
    1. Let number be ? ToNumber(argument).
    2. If number is NaN, return +0.
    3. If number ≤ 0, return +0.
    4. If number ≥ 255, return 255.
    5. Let f be floor(number).
    6. If f + 0.5 < number, return f + 1.
    7. If number < f + 0.5, return f.
    8. If f is odd, return f + 1.
    9. Return f.
    Note
    -

    Unlike the other ECMAScript integer conversion abstract -operation, ToUint8Clamp rounds rather than truncates non-integer values +

    Unlike the other ECMAScript integer conversion abstract +operation, ToUint8Clamp rounds rather than truncates non-integer values and does not convert +∞ to 0. ToUint8Clamp does “round half to even” tie-breaking. This differs from Math.round which does “round half up” tie-breaking.

     @@ -4939,37 +4939,37 @@ and does not convert +∞ to 0. ToUint8Clamp does “round ha Argument Type - + Result - + Undefined - + Return "undefined". - + Null - + Return "null". - + Boolean - +

    If argument is true, return "true".

    @@ -4979,37 +4979,37 @@ and does not convert +∞ to 0. ToUint8Clamp does “round ha Number - + Return NumberToString(argument). - + String - + Return argument. - + Symbol - + Throw a TypeError exception. - + Object - +

    Apply the following steps:

    @@ -5027,42 +5027,42 @@ and does not convert +∞ to 0. ToUint8Clamp does “round ha
    1. If m is NaN, return the String "NaN".
    2. If m is +0 or -0, return the String "0".
    3. If m is less than zero, return the string-concatenation of "-" and ! NumberToString(-m).
    4. If m is +∞, return the String "Infinity".
    5. Otherwise, let n, k, and s be integers such that k ≥ 1, 10k - 1 ≤ s < 10k, the Number value for s × 10n - k is m, and k is as small as possible. Note that k is the number of digits in the decimal representation of s, that s is not divisible by 10, and that the least significant digit of s is not necessarily uniquely determined by these criteria.
    6. If k ≤ n ≤ 21, return the string-concatenation of:
      • the code units of the k digits of the decimal representation of s (in order, with no leading zeroes)
      • n - k occurrences of the code unit 0x0030 (DIGIT ZERO)
    7. If 0 < n ≤ 21, return the string-concatenation of:
      • the code units of the most significant n digits of the decimal representation of s
      • the code unit 0x002E (FULL STOP)
      • the code units of the remaining k - n digits of the decimal representation of s
    8. If -6 < n ≤ 0, return the string-concatenation of:
      • the code unit 0x0030 (DIGIT ZERO)
      • the code unit 0x002E (FULL STOP)
      • -n occurrences of the code unit 0x0030 (DIGIT ZERO)
      • the code units of the k digits of the decimal representation of s
    9. Otherwise, if k = 1, return the string-concatenation of:
      • the code unit of the single digit of s
      • the code unit 0x0065 (LATIN SMALL LETTER E)
      • the code unit 0x002B (PLUS SIGN) or the code unit 0x002D (HYPHEN-MINUS) according to whether n - 1 is positive or negative
      • the code units of the decimal representation of the integer abs(n - 1) (with no leading zeroes)
    10. Return the string-concatenation of:
      • the code units of the most significant digit of the decimal representation of s
      • the code unit 0x002E (FULL STOP)
      • the code units of the remaining k - 1 digits of the decimal representation of s
      • the code unit 0x0065 (LATIN SMALL LETTER E)
      • the code unit 0x002B (PLUS SIGN) or the code unit 0x002D (HYPHEN-MINUS) according to whether n - 1 is positive or negative
      • the code units of the decimal representation of the integer abs(n - 1) (with no leading zeroes)
    Note 1
    -

    The following observations may be useful as guidelines for -implementations, but are not part of the normative requirements of this +

    The following observations may be useful as guidelines for +implementations, but are not part of the normative requirements of this Standard:

    • If x is any Number value other than -0, then ToNumber(ToString(x)) is exactly the same Number value as x. - +
    • The least significant digit of s is not always uniquely determined by the requirements listed in step 5. - +
    Note 2
    -

    For implementations that provide more accurate conversions -than required by the rules above, it is recommended that the following +

    For implementations that provide more accurate conversions +than required by the rules above, it is recommended that the following alternative version of step 5 be used as a guideline:

    1. Otherwise, let n, k, and s be integers such that k ≥ 1, 10k - 1 ≤ s < 10k, the Number value for s × 10n - k is m, and k is as small as possible. If there are multiple possibilities for s, choose the value of s for which s × 10n - k is closest in value to m. If there are two such possible values of s, choose the one that is even. Note that k is the number of digits in the decimal representation of s and that s is not divisible by 10.
    Note 3
    -

    Implementers of ECMAScript may find useful the paper and -code written by David M. Gay for binary-to-decimal conversion of +

    Implementers of ECMAScript may find useful the paper and +code written by David M. Gay for binary-to-decimal conversion of floating-point numbers:

    -

    Gay, David M. Correctly Rounded Binary-Decimal and -Decimal-Binary Conversions. Numerical Analysis, Manuscript 90-10. +

    Gay, David M. Correctly Rounded Binary-Decimal and +Decimal-Binary Conversions. Numerical Analysis, Manuscript 90-10. AT&T Bell Laboratories (Murray Hill, New Jersey). November 30, 1990. Available as - +
    http://ampl.com/REFS/abstracts.html#rounding. Associated code available as - +
    http://netlib.sandia.gov/fp/dtoa.c and as - +
    http://netlib.sandia.gov/fp/g_fmt.c and may also be found at the various netlib mirror sites.

     @@ -5078,81 +5078,81 @@ AT&T Bell Laboratories (Murray Hill, New Jersey). November 30, 1990. Argument Type - + Result - + Undefined - + Throw a TypeError exception. - + Null - + Throw a TypeError exception. - + Boolean - + Return a new Boolean object whose [[BooleanData]] internal slot is set to argument. See 19.3 for a description of Boolean objects. - + Number - + Return a new Number object whose [[NumberData]] internal slot is set to argument. See 20.1 for a description of Number objects. - + String - + Return a new String object whose [[StringData]] internal slot is set to argument. See 21.1 for a description of String objects. - + Symbol - + Return a new Symbol object whose [[SymbolData]] internal slot is set to argument. See 19.4 for a description of Symbol objects. - + Object - + Return argument. - + @@ -5202,81 +5202,81 @@ AT&T Bell Laboratories (Murray Hill, New Jersey). November 30, 1990. Argument Type - + Result - + Undefined - + Throw a TypeError exception. - + Null - + Throw a TypeError exception. - + Boolean - + Return argument. - + Number - + Return argument. - + String - + Return argument. - + Symbol - + Return argument. - + Object - + Return argument. - + @@ -5370,7 +5370,7 @@ AT&T Bell Laboratories (Murray Hill, New Jersey). November 30, 1990.

    7.2.13Abstract Relational Comparison

    The comparison x < y, where x and y are values, produces true, false, or undefined (which indicates that at least one operand is NaN). In addition to x and y the algorithm takes a Boolean flag named LeftFirst - as a parameter. The flag is used to control the order in which + as a parameter. The flag is used to control the order in which operations with potentially visible side-effects are performed upon x and y. It is necessary because ECMAScript specifies left to right evaluation of expressions. The default value of LeftFirst is true and indicates that the x parameter corresponds to an expression that occurs to the left of the y parameter's corresponding expression. If LeftFirst is false, the reverse is the case and operations must be performed upon y before x. Such a comparison is performed as follows:

    1. If the LeftFirst flag is true, then
      1. Let px be ? ToPrimitive(x, hint Number).
      2. Let py be ? ToPrimitive(y, hint Number).
    2. Else the order of evaluation needs to be reversed to preserve left to right evaluation,
      1. Let py be ? ToPrimitive(y, hint Number).
      2. Let px be ? ToPrimitive(x, hint Number).
    3. If Type(px) is String and Type(py) is String, then
      1. If IsStringPrefix(py, px) is true, return false.
      2. If IsStringPrefix(px, py) is true, return true.
      3. Let k be the smallest nonnegative integer such that the code unit at index k within px is different from the code unit at index k within py. (There must be such a k, for neither String is a prefix of the other.)
      4. Let m be the integer that is the numeric value of the code unit at index k within px.
      5. Let n be the integer that is the numeric value of the code unit at index k within py.
      6. If m < n, return true. Otherwise, return false.
    4. Else,
      1. NOTE: Because px and py are primitive values evaluation order is not important.
      2. Let nx be ? ToNumber(px).
      3. Let ny be ? ToNumber(py).
      4. If nx is NaN, return undefined.
      5. If ny is NaN, return undefined.
      6. If nx and ny are the same Number value, return false.
      7. If nx is +0 and ny is -0, return false.
      8. If nx is -0 and ny is +0, return false.
      9. If nx is +∞, return false.
      10. If ny is +∞, return true.
      11. If ny is -∞, return false.
      12. If nx is -∞, return true.
      13. If the mathematical value of nx is less than the mathematical value of ny—note that these mathematical values are both finite and not both zero—return true. Otherwise, return false.
    @@ -5378,15 +5378,15 @@ operations with potentially visible side-effects are performed upon x

    Step 3 differs from step 7 in the algorithm for the addition operator + (12.8.3) by using the logical-and operation instead of the logical-or operation.

    Note 2
    -

    The comparison of Strings uses a simple lexicographic -ordering on sequences of code unit values. There is no attempt to use -the more complex, semantically oriented definitions of character or -string equality and collating order defined in the Unicode -specification. Therefore String values that are canonically equal -according to the Unicode standard could test as unequal. In effect this -algorithm assumes that both Strings are already in normalized form. -Also, note that for strings containing supplementary characters, -lexicographic ordering on sequences of UTF-16 code unit values differs +

    The comparison of Strings uses a simple lexicographic +ordering on sequences of code unit values. There is no attempt to use +the more complex, semantically oriented definitions of character or +string equality and collating order defined in the Unicode +specification. Therefore String values that are canonically equal +according to the Unicode standard could test as unequal. In effect this +algorithm assumes that both Strings are already in normalized form. +Also, note that for strings containing supplementary characters, +lexicographic ordering on sequences of UTF-16 code unit values differs from that on sequences of code point values.

         @@ -5414,7 +5414,7 @@ from that on sequences of code point values.

    7.3.1Get ( O, P )

    -

    The abstract operation Get is used to retrieve the value of a +

    The abstract operation Get is used to retrieve the value of a specific property of an object. The operation is called with arguments O and P where O is the object and P is the property key. This abstract operation performs the following steps:

    1. Assert: Type(O) is Object.
    2. Assert: IsPropertyKey(P) is true.
    3. Return ? O.[[Get]](P, O).
    @@ -5424,7 +5424,7 @@ specific property of an object. The operation is called with arguments O7.3.2GetV ( V, P )

    The abstract operation GetV is used to retrieve the value of a specific property of an ECMAScript language value. If the value is not an object, the property lookup is performed using a - wrapper object appropriate for the type of the value. The operation is + wrapper object appropriate for the type of the value. The operation is called with arguments V and P where V is the value and P is the property key. This abstract operation performs the following steps:

    1. Assert: IsPropertyKey(P) is true.
    2. Let O be ? ToObject(V).
    3. Return ? O.[[Get]](P, V).
    @@ -5439,13 +5439,13 @@ called with arguments V and P where V is the va

    7.3.4CreateDataProperty ( O, P, V )

    -

    The abstract operation CreateDataProperty is used to create a +

    The abstract operation CreateDataProperty is used to create a new own property of an object. The operation is called with arguments O, P, and V where O is the object, P is the property key, and V is the value for the property. This abstract operation performs the following steps:

    1. Assert: Type(O) is Object.
    2. Assert: IsPropertyKey(P) is true.
    3. Let newDesc be the PropertyDescriptor { [[Value]]: V, [[Writable]]: true, [[Enumerable]]: true, [[Configurable]]: true }.
    4. Return ? O.[[DefineOwnProperty]](P, newDesc).
    Note
    -

    This abstract operation creates a property whose attributes -are set to the same defaults used for properties created by the +

    This abstract operation creates a property whose attributes +are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if O is not extensible, [[DefineOwnProperty]] will return false.

     @@ -5458,9 +5458,9 @@ ECMAScript language assignment operator. Normally, the property will not
    1. Assert: Type(O) is Object.
    2. Assert: IsPropertyKey(P) is true.
    3. Let newDesc be the PropertyDescriptor { [[Value]]: V, [[Writable]]: true, [[Enumerable]]: false, [[Configurable]]: true }.
    4. Return ? O.[[DefineOwnProperty]](P, newDesc).
    Note
    -

    This abstract operation creates a property whose attributes -are set to the same defaults used for built-in methods and methods -defined using class declaration syntax. Normally, the property will not +

    This abstract operation creates a property whose attributes +are set to the same defaults used for built-in methods and methods +defined using class declaration syntax. Normally, the property will not already exist. If it does exist and is not configurable or if O is not extensible, [[DefineOwnProperty]] will return false.

         @@ -5471,8 +5471,8 @@ already exist. If it does exist and is not configurable or if O is no
    1. Assert: Type(O) is Object.
    2. Assert: IsPropertyKey(P) is true.
    3. Let success be ? CreateDataProperty(O, P, V).
    4. If success is false, throw a TypeError exception.
    5. Return success.
    Note
    -

    This abstract operation creates a property whose attributes -are set to the same defaults used for properties created by the +

    This abstract operation creates a property whose attributes +are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if O is not extensible, [[DefineOwnProperty]] will return false causing this operation to throw a TypeError exception.

     @@ -5480,8 +5480,8 @@ ECMAScript language assignment operator. Normally, the property will not

    7.3.7DefinePropertyOrThrow ( O, P, desc )

    -

    The abstract operation DefinePropertyOrThrow is used to call -the [[DefineOwnProperty]] internal method of an object in a manner that +

    The abstract operation DefinePropertyOrThrow is used to call +the [[DefineOwnProperty]] internal method of an object in a manner that will throw a TypeError exception if the requested property update cannot be performed. The operation is called with arguments O, P, and desc where O is the object, P is the property key, and desc is the Property Descriptor for the property. This abstract operation performs the following steps:

    1. Assert: Type(O) is Object.
    2. Assert: IsPropertyKey(P) is true.
    3. Let success be ? O.[[DefineOwnProperty]](P, desc).
    4. If success is false, throw a TypeError exception.
    5. Return success.
    @@ -5490,7 +5490,7 @@ will throw a TypeError exception if the requested property up

    7.3.8DeletePropertyOrThrow ( O, P )

    The abstract operation DeletePropertyOrThrow is used to remove a - specific own property of an object. It throws an exception if the + specific own property of an object. It throws an exception if the property is not configurable. The operation is called with arguments O and P where O is the object and P is the property key. This abstract operation performs the following steps:

    1. Assert: Type(O) is Object.
    2. Assert: IsPropertyKey(P) is true.
    3. Let success be ? O.[[Delete]](P).
    4. If success is false, throw a TypeError exception.
    5. Return success.
    @@ -5506,8 +5506,8 @@ property is not configurable. The operation is called with arguments O

    7.3.10HasProperty ( O, P )

    The abstract operation HasProperty is used to determine whether - an object has a property with the specified property key. The property -may be either an own or inherited. A Boolean value is returned. The + an object has a property with the specified property key. The property +may be either an own or inherited. A Boolean value is returned. The operation is called with arguments O and P where O is the object and P is the property key. This abstract operation performs the following steps:

    1. Assert: Type(O) is Object.
    2. Assert: IsPropertyKey(P) is true.
    3. Return ? O.[[HasProperty]](P).
    @@ -5515,7 +5515,7 @@ operation is called with arguments O and P where O

    7.3.11HasOwnProperty ( O, P )

    -

    The abstract operation HasOwnProperty is used to determine +

    The abstract operation HasOwnProperty is used to determine whether an object has an own property with the specified property key. A Boolean value is returned. The operation is called with arguments O and P where O is the object and P is the property key. This abstract operation performs the following steps:

    1. Assert: Type(O) is Object.
    2. Assert: IsPropertyKey(P) is true.
    3. Let desc be ? O.[[GetOwnProperty]](P).
    4. If desc is undefined, return false.
    5. Return true. @@ -5542,7 +5542,7 @@ whether an object has an own property with the specified property key. A

      7.3.14SetIntegrityLevel ( O, level )

      The abstract operation SetIntegrityLevel is used to fix the set - of own properties of an object. This abstract operation performs the + of own properties of an object. This abstract operation performs the following steps:

      1. Assert: Type(O) is Object.
      2. Assert: level is either "sealed" or "frozen".
      3. Let status be ? O.[[PreventExtensions]]().
      4. If status is false, return false.
      5. Let keys be ? O.[[OwnPropertyKeys]]().
      6. If level is "sealed", then
        1. For each element k of keys, do
          1. Perform ? DefinePropertyOrThrow(O, k, PropertyDescriptor { [[Configurable]]: false }).
      7. Else level is "frozen",
        1. For each element k of keys, do
          1. Let currentDesc be ? O.[[GetOwnProperty]](k).
          2. If currentDesc is not undefined, then
            1. If IsAccessorDescriptor(currentDesc) is true, then
              1. Let desc be the PropertyDescriptor { [[Configurable]]: false }.
            2. Else,
              1. Let desc be the PropertyDescriptor { [[Configurable]]: false, [[Writable]]: false }.
            3. Perform ? DefinePropertyOrThrow(O, k, desc).
      8. Return true.
      @@ -5550,8 +5550,8 @@ following steps:

      7.3.15TestIntegrityLevel ( O, level )

      -

      The abstract operation TestIntegrityLevel is used to determine -if the set of own properties of an object are fixed. This abstract +

      The abstract operation TestIntegrityLevel is used to determine +if the set of own properties of an object are fixed. This abstract operation performs the following steps:

      1. Assert: Type(O) is Object.
      2. Assert: level is either "sealed" or "frozen".
      3. Let status be ? IsExtensible(O).
      4. If status is true, return false.
      5. NOTE: If the object is extensible, none of its properties are examined.
      6. Let keys be ? O.[[OwnPropertyKeys]]().
      7. For each element k of keys, do
        1. Let currentDesc be ? O.[[GetOwnProperty]](k).
        2. If currentDesc is not undefined, then
          1. If currentDesc.[[Configurable]] is true, return false.
          2. If level is "frozen" and IsDataDescriptor(currentDesc) is true, then
            1. If currentDesc.[[Writable]] is true, return false.
      8. Return true.
      @@ -5657,7 +5657,7 @@ operation performs the following steps:

      7.4.5IteratorStep ( iteratorRecord )

      The abstract operation IteratorStep with argument iteratorRecord requests the next value from iteratorRecord.[[Iterator]] by calling iteratorRecord.[[NextMethod]] and returns either false - indicating that the iterator has reached its end or the IteratorResult + indicating that the iterator has reached its end or the IteratorResult object if a next value is available. IteratorStep performs the following steps:

      1. Let result be ? IteratorNext(iteratorRecord).
      2. Let done be ? IteratorComplete(result).
      3. If done is true, return false.
      4. Return result. @@ -5667,7 +5667,7 @@ object if a next value is available. IteratorStep performs the following

        7.4.6IteratorClose ( iteratorRecord, completion )

        The abstract operation IteratorClose with arguments iteratorRecord and completion - is used to notify an iterator that it should perform any actions it + is used to notify an iterator that it should perform any actions it would normally perform when it has reached its completed state:

        1. Assert: Type(iteratorRecord.[[Iterator]]) is Object.
        2. Assert: completion is a Completion Record.
        3. Let iterator be iteratorRecord.[[Iterator]].
        4. Let return be ? GetMethod(iterator, "return").
        5. If return is undefined, return Completion(completion).
        6. Let innerResult be Call(return, iterator, « »).
        7. If completion.[[Type]] is throw, return Completion(completion).
        8. If innerResult.[[Type]] is throw, return Completion(innerResult).
        9. If Type(innerResult.[[Value]]) is not Object, throw a TypeError exception.
        10. Return Completion(completion).
        @@ -5676,7 +5676,7 @@ would normally perform when it has reached its completed state:

        7.4.7AsyncIteratorClose ( iteratorRecord, completion )

        The abstract operation AsyncIteratorClose with arguments iteratorRecord and completion - is used to notify an async iterator that it should perform any actions + is used to notify an async iterator that it should perform any actions it would normally perform when it has reached its completed state:

        1. Assert: Type(iteratorRecord.[[Iterator]]) is Object.
        2. Assert: completion is a Completion Record.
        3. Let iterator be iteratorRecord.[[Iterator]].
        4. Let return be ? GetMethod(iterator, "return").
        5. If return is undefined, return Completion(completion).
        6. Let innerResult be Call(return, iterator, « »).
        7. If innerResult.[[Type]] is normal, set innerResult to Await(innerResult.[[Value]]).
        8. If completion.[[Type]] is throw, return Completion(completion).
        9. If innerResult.[[Type]] is throw, return Completion(innerResult).
        10. If Type(innerResult.[[Value]]) is not Object, throw a TypeError exception.
        11. Return Completion(completion).
        @@ -5714,48 +5714,48 @@ it would normally perform when it has reached its completed state:

        8.1Lexical Environments

        A Lexical Environment is a specification type used to define the association of Identifiers - to specific variables and functions based upon the lexical nesting + to specific variables and functions based upon the lexical nesting structure of ECMAScript code. A Lexical Environment consists of an Environment Record and a possibly null reference to an outer - Lexical Environment. Usually a Lexical Environment is associated with + Lexical Environment. Usually a Lexical Environment is associated with some specific syntactic structure of ECMAScript code such as a FunctionDeclaration, a BlockStatement, or a Catch clause of a TryStatement and a new Lexical Environment is created each time such code is evaluated.

        An Environment Record - records the identifier bindings that are created within the scope of -its associated Lexical Environment. It is referred to as the Lexical + records the identifier bindings that are created within the scope of +its associated Lexical Environment. It is referred to as the Lexical Environment's EnvironmentRecord.

        -

        The outer environment reference is used to model the logical -nesting of Lexical Environment values. The outer reference of a (inner) -Lexical Environment is a reference to the Lexical Environment that -logically surrounds the inner Lexical Environment. An outer Lexical -Environment may, of course, have its own outer Lexical Environment. A -Lexical Environment may serve as the outer environment for multiple +

        The outer environment reference is used to model the logical +nesting of Lexical Environment values. The outer reference of a (inner) +Lexical Environment is a reference to the Lexical Environment that +logically surrounds the inner Lexical Environment. An outer Lexical +Environment may, of course, have its own outer Lexical Environment. A +Lexical Environment may serve as the outer environment for multiple inner Lexical Environments. For example, if a FunctionDeclaration contains two nested FunctionDeclarations then the Lexical Environments of each of the nested functions will have - as their outer Lexical Environment the Lexical Environment of the + as their outer Lexical Environment the Lexical Environment of the current evaluation of the surrounding function.

        A global environment is a Lexical Environment which does not have an outer environment. The global environment's outer environment reference is null. A global environment's EnvironmentRecord may be prepopulated with identifier bindings and includes an associated global object whose properties provide some of the global environment's identifier bindings. As ECMAScript code is executed, additional properties may be added to the global object and the initial properties may be modified.

        A module environment is a Lexical Environment that contains the bindings for the top level declarations of a Module. It also contains the bindings that are explicitly imported by the Module. The outer environment of a module environment is a global environment.

        A function environment is a Lexical Environment that corresponds to the invocation of an ECMAScript function object. A function environment may establish a new this binding. A function environment also captures the state necessary to support super method invocations.

        Lexical Environments and Environment Record - values are purely specification mechanisms and need not correspond to -any specific artefact of an ECMAScript implementation. It is impossible + values are purely specification mechanisms and need not correspond to +any specific artefact of an ECMAScript implementation. It is impossible for an ECMAScript program to directly access or manipulate such values.

        8.1.1Environment Records

        There are two primary kinds of Environment Record values used in this specification: declarative Environment Records and object Environment Records. Declarative Environment Records are used to define the effect of ECMAScript language syntactic elements such as FunctionDeclarations, VariableDeclarations, and Catch - clauses that directly associate identifier bindings with ECMAScript -language values. Object Environment Records are used to define the + clauses that directly associate identifier bindings with ECMAScript +language values. Object Environment Records are used to define the effect of ECMAScript elements such as WithStatement - that associate identifier bindings with the properties of some object. -Global Environment Records and function Environment Records are + that associate identifier bindings with the properties of some object. +Global Environment Records and function Environment Records are specializations that are used for specifically for Script global declarations and for top-level declarations within functions.

        For specification purposes Environment Record values are values of the Record - specification type and can be thought of as existing in a simple -object-oriented hierarchy where Environment Record is an abstract class -with three concrete subclasses, declarative Environment Record, object -Environment Record, and global Environment Record. Function Environment -Records and module Environment Records are subclasses of declarative -Environment Record. The abstract class includes the abstract + specification type and can be thought of as existing in a simple +object-oriented hierarchy where Environment Record is an abstract class +with three concrete subclasses, declarative Environment Record, object +Environment Record, and global Environment Record. Function Environment +Records and module Environment Records are subclasses of declarative +Environment Record. The abstract class includes the abstract specification methods defined in Table 14. These abstract methods have distinct concrete algorithms for each of the concrete subclasses.

        Table 14: Abstract Methods of Environment Records
        @@ -5763,114 +5763,114 @@ specification methods defined in @@ -5880,8 +5880,8 @@ reference that binding.

        8.1.1.1Declarative Environment Records

        Each declarative Environment Record - is associated with an ECMAScript program scope containing variable, -constant, let, class, module, import, and/or function declarations. A + is associated with an ECMAScript program scope containing variable, +constant, let, class, module, import, and/or function declarations. A declarative Environment Record binds the set of identifiers defined by the declarations contained within its scope.

        The behaviour of the concrete specification methods for declarative Environment Records is defined by the following algorithms.

        @@ -5889,7 +5889,7 @@ declarative 8.1.1.1.1HasBinding ( N )

        The concrete Environment Record method HasBinding for declarative Environment Records simply determines - if the argument identifier is one of the identifiers bound by the + if the argument identifier is one of the identifiers bound by the record:

        1. Let envRec be the declarative Environment Record for which the method was invoked.
        2. If envRec has a binding for the name that is the value of N, return true.
        3. Return false.
        @@ -5922,7 +5922,7 @@ record:

        8.1.1.1.5SetMutableBinding ( N, V, S )

        The concrete Environment Record - method SetMutableBinding for declarative Environment Records attempts + method SetMutableBinding for declarative Environment Records attempts to change the bound value of the current binding of the identifier whose name is the value of the argument N to the value of argument V. A binding for N normally already exists, but in rare cases it may not. If the binding is an immutable binding, a TypeError is thrown if S is true.

        1. Let envRec be the declarative Environment Record for which the method was invoked.
        2. If envRec does not have a binding for N, then
          1. If S is true, throw a ReferenceError exception.
          2. Perform envRec.CreateMutableBinding(N, true).
          3. Perform envRec.InitializeBinding(N, V).
          4. Return NormalCompletion(empty).
        3. If the binding for N in envRec is a strict binding, set S to true.
        4. If the binding for N in envRec has not yet been initialized, throw a ReferenceError exception.
        5. Else if the binding for N in envRec is a mutable binding, change its bound value to V.
        6. Else,
          1. Assert: This is an attempt to change the value of an immutable binding.
          2. If S is true, throw a TypeError exception.
        7. Return NormalCompletion(empty). @@ -5936,7 +5936,7 @@ to change the bound value of the current binding of the identifier whose

          8.1.1.1.6GetBindingValue ( N, S )

          The concrete Environment Record - method GetBindingValue for declarative Environment Records simply + method GetBindingValue for declarative Environment Records simply returns the value of its bound identifier whose name is the value of the argument N. If the binding exists but is uninitialized a ReferenceError is thrown, regardless of the value of S.

          1. Let envRec be the declarative Environment Record for which the method was invoked.
          2. Assert: envRec has a binding for N.
          3. If the binding for N in envRec is an uninitialized binding, throw a ReferenceError exception.
          4. Return the value currently bound to N in envRec. @@ -5946,7 +5946,7 @@ returns the value of its bound identifier whose name is the value of the

            8.1.1.1.7DeleteBinding ( N )

            The concrete Environment Record - method DeleteBinding for declarative Environment Records can only + method DeleteBinding for declarative Environment Records can only delete bindings that have been explicitly designated as being subject to deletion.

            1. Let envRec be the declarative Environment Record for which the method was invoked.
            2. Assert: envRec has a binding for the name that is the value of N.
            3. If the binding for N in envRec cannot be deleted, return false.
            4. Remove the binding for N from envRec.
            5. Return true. @@ -5978,17 +5978,17 @@ delete bindings that have been explicitly designated as being subject to

              8.1.1.2Object Environment Records

              Each object Environment Record is associated with an object called its binding object. An object Environment Record - binds the set of string identifier names that directly correspond to -the property names of its binding object. Property keys that are not + binds the set of string identifier names that directly correspond to +the property names of its binding object. Property keys that are not strings in the form of an IdentifierName - are not included in the set of bound identifiers. Both own and -inherited properties are included in the set regardless of the setting + are not included in the set of bound identifiers. Both own and +inherited properties are included in the set regardless of the setting of their [[Enumerable]] attribute. Because properties can be dynamically - added and deleted from objects, the set of identifiers bound by an + added and deleted from objects, the set of identifiers bound by an object Environment Record - may potentially change as a side-effect of any operation that adds or -deletes properties. Any bindings that are created as a result of such a -side-effect are considered to be a mutable binding even if the Writable + may potentially change as a side-effect of any operation that adds or +deletes properties. Any bindings that are created as a result of such a +side-effect are considered to be a mutable binding even if the Writable attribute of the corresponding property has the value false. Immutable bindings do not exist for object Environment Records.

              Object Environment Records created for with statements (13.11) can provide their binding object as an implicit this value for use in function calls. The capability is controlled by a withEnvironment Boolean value that is associated with each object Environment Record. By default, the value of withEnvironment is false for any object Environment Record.

              The behaviour of the concrete specification methods for object Environment Records is defined by the following algorithms.

              @@ -5996,8 +5996,8 @@ attribute of the corresponding property has the value false.

              8.1.1.2.1HasBinding ( N )

              The concrete Environment Record - method HasBinding for object Environment Records determines if its -associated binding object has a property whose name is the value of the + method HasBinding for object Environment Records determines if its +associated binding object has a property whose name is the value of the argument N:

              1. Let envRec be the object Environment Record for which the method was invoked.
              2. Let bindings be the binding object for envRec.
              3. Let foundBinding be ? HasProperty(bindings, N).
              4. If foundBinding is false, return false.
              5. If the withEnvironment flag of envRec is false, return true.
              6. Let unscopables be ? Get(bindings, @@unscopables).
              7. If Type(unscopables) is Object, then
                1. Let blocked be ToBoolean(? Get(unscopables, N)).
                2. If blocked is true, return false.
              8. Return true.
              @@ -6021,15 +6021,15 @@ argument N:

              8.1.1.2.4InitializeBinding ( N, V )

              The concrete Environment Record - method InitializeBinding for object Environment Records is used to set -the bound value of the current binding of the identifier whose name is + method InitializeBinding for object Environment Records is used to set +the bound value of the current binding of the identifier whose name is the value of the argument N to the value of argument V. An uninitialized binding for N must already exist.

              1. Let envRec be the object Environment Record for which the method was invoked.
              2. Assert: envRec must have an uninitialized binding for N.
              3. Record that the binding for N in envRec has been initialized.
              4. Return ? envRec.SetMutableBinding(N, V, false).
              Note
              -

              In this specification, all uses of CreateMutableBinding -for object Environment Records are immediately followed by a call to -InitializeBinding for the same name. Hence, implementations do not need +

              In this specification, all uses of CreateMutableBinding +for object Environment Records are immediately followed by a call to +InitializeBinding for the same name. Hence, implementations do not need to explicitly track the initialization state of individual object Environment Record bindings.

                             @@ -6037,8 +6037,8 @@ to explicitly track the initialization state of individual object

              8.1.1.2.5SetMutableBinding ( N, V, S )

              The concrete Environment Record method SetMutableBinding for object Environment Records attempts to set the value of the Environment Record's associated binding object's property whose name is the value of the argument N to the value of argument V. A property named N - normally already exists but if it does not or is not currently -writable, error handling is determined by the value of the Boolean + normally already exists but if it does not or is not currently +writable, error handling is determined by the value of the Boolean argument S.

              1. Let envRec be the object Environment Record for which the method was invoked.
              2. Let bindings be the binding object for envRec.
              3. Return ? Set(bindings, N, V, S).
              @@ -6048,7 +6048,7 @@ argument S.

              8.1.1.2.6GetBindingValue ( N, S )

              The concrete Environment Record method GetBindingValue for object Environment Records returns the value - of its associated binding object's property whose name is the String + of its associated binding object's property whose name is the String value of the argument identifier N. The property should already exist but if it does not the result depends upon the value of the S argument:

              1. Let envRec be the object Environment Record for which the method was invoked.
              2. Let bindings be the binding object for envRec.
              3. Let value be ? HasProperty(bindings, N).
              4. If value is false, then
                1. If S is false, return the value undefined; otherwise throw a ReferenceError exception.
              5. Return ? Get(bindings, N).
              @@ -6057,8 +6057,8 @@ value of the argument identifier N. The property should already exist

              8.1.1.2.7DeleteBinding ( N )

              The concrete Environment Record - method DeleteBinding for object Environment Records can only delete -bindings that correspond to properties of the environment object whose + method DeleteBinding for object Environment Records can only delete +bindings that correspond to properties of the environment object whose [[Configurable]] attribute have the value true.

              1. Let envRec be the object Environment Record for which the method was invoked.
              2. Let bindings be the binding object for envRec.
              3. Return ? bindings.[[Delete]](N).
              @@ -6096,93 +6096,93 @@ bindings that correspond to properties of the environment object whose
        Method - + Purpose - +
        HasBinding(N) - + Determine if an Environment Record has a binding for the String value N. Return true if it does and false if it does not. - +
        CreateMutableBinding(N, D) - + Create a new but uninitialized mutable binding in an Environment Record. The String value N is the text of the bound name. If the Boolean argument D is true the binding may be subsequently deleted. - +
        CreateImmutableBinding(N, S) - + Create a new but uninitialized immutable binding in an Environment Record. The String value N is the text of the bound name. If S is true then attempts to set it after it has been initialized will always throw - an exception, regardless of the strict mode setting of operations that + an exception, regardless of the strict mode setting of operations that reference that binding. - +
        InitializeBinding(N, V) - + Set the value of an already existing but uninitialized binding in an Environment Record. The String value N is the text of the bound name. V is the value for the binding and is a value of any ECMAScript language type. - +
        SetMutableBinding(N, V, S) - + Set the value of an already existing mutable binding in an Environment Record. The String value N is the text of the bound name. V is the value for the binding and may be a value of any ECMAScript language type. S is a Boolean flag. If S is true and the binding cannot be set throw a TypeError exception. - +
        GetBindingValue(N, S) - + Returns the value of an already existing binding from an Environment Record. The String value N is the text of the bound name. S is used to identify references originating in strict mode code or that otherwise require strict mode reference semantics. If S is true and the binding does not exist throw a ReferenceError exception. If the binding exists but is uninitialized a ReferenceError is thrown, regardless of the value of S. - +
        DeleteBinding(N) - + Delete a binding from an Environment Record. The String value N is the text of the bound name. If a binding for N exists, remove the binding and return true. If the binding exists but cannot be removed return false. If the binding does not exist return true. - +
        HasThisBinding() - + Determine if an Environment Record establishes a this binding. Return true if it does and false if it does not. - +
        HasSuperBinding() - + Determine if an Environment Record establishes a super method binding. Return true if it does and false if it does not. - +
        WithBaseObject() - + If this Environment Record is associated with a with statement, return the with object. Otherwise, return undefined. - +
        Field Name - + Value - + Meaning - +
        [[ThisValue]] - + Any - + This is the this value used for this invocation of the function. - +
        [[ThisBindingStatus]] - + "lexical" | "initialized" | "uninitialized" - + If the value is "lexical", this is an ArrowFunction and does not have a local this value. - +
        [[FunctionObject]] - + Object - + The function object whose invocation caused this Environment Record to be created. - +
        [[HomeObject]] - + Object | undefined - + If the associated function has super property accesses and is not an ArrowFunction, [[HomeObject]] is the object that the function is bound to as a method. The default value for [[HomeObject]] is undefined. - +
        [[NewTarget]] - + Object | undefined - + If this Environment Record was created by the [[Construct]] internal method, [[NewTarget]] is the value of the [[Construct]] newTarget parameter. Otherwise, its value is undefined. - +

        Function Environment Records support all of the declarative Environment Record methods listed in Table 14 - and share the same specifications for all of those methods except for -HasThisBinding and HasSuperBinding. In addition, function Environment + and share the same specifications for all of those methods except for +HasThisBinding and HasSuperBinding. In addition, function Environment Records support the methods listed in Table 16:

        Table 16: Additional Methods of Function Environment Records
        @@ -6190,48 +6190,48 @@ Records support the methods listed in
        Method - + Purpose - +
        BindThisValue(V) - + Set the [[ThisValue]] and record that it has been initialized. - +
        GetThisBinding() - + Return the value of this Environment Record's this binding. Throws a ReferenceError if the this binding has not been initialized. - +
        GetSuperBase() - + Return the object that is the base for super property accesses bound in this Environment Record. The object is derived from this Environment Record's [[HomeObject]] field. The value undefined indicates that super property accesses will produce runtime errors. - +
        -

        The behaviour of the additional concrete specification -methods for function Environment Records is defined by the following +

        The behaviour of the additional concrete specification +methods for function Environment Records is defined by the following algorithms:

        @@ -6277,71 +6277,71 @@ algorithms:

        Field Name - + Value - + Meaning - + [[ObjectRecord]] - + Object Environment Record - + Binding object is the global object. It contains global built-in bindings as well as FunctionDeclaration, GeneratorDeclaration, AsyncFunctionDeclaration, AsyncGeneratorDeclaration, and VariableDeclaration bindings in global code for the associated realm. - + [[GlobalThisValue]] - + Object - + The value returned by this in global scope. Hosts may provide any ECMAScript Object value. - + [[DeclarativeRecord]] - + Declarative Environment Record - + Contains bindings for all declarations in global code for the associated realm code except for FunctionDeclaration, GeneratorDeclaration, AsyncFunctionDeclaration, AsyncGeneratorDeclaration, and VariableDeclaration bindings. - + [[VarNames]] - + List of String - + The string names bound by FunctionDeclaration, GeneratorDeclaration, AsyncFunctionDeclaration, AsyncGeneratorDeclaration, and VariableDeclaration declarations in global code for the associated realm. - + @@ -6353,97 +6353,97 @@ algorithms:

        Method - + Purpose - + GetThisBinding() - + Return the value of this Environment Record's this binding. - + HasVarDeclaration (N) - + Determines if the argument identifier has a binding in this Environment Record that was created using a VariableDeclaration, FunctionDeclaration, GeneratorDeclaration, AsyncFunctionDeclaration, or AsyncGeneratorDeclaration. - + HasLexicalDeclaration (N) - + Determines if the argument identifier has a binding in this Environment Record that was created using a lexical declaration such as a LexicalDeclaration or a ClassDeclaration. - + HasRestrictedGlobalProperty (N) - + Determines if the argument is the name of a global object property that may not be shadowed by a global lexical binding. - + CanDeclareGlobalVar (N) - + Determines if a corresponding CreateGlobalVarBinding call would succeed if called for the same argument N. - + CanDeclareGlobalFunction (N) - + Determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument N. - + CreateGlobalVarBinding(N, D) - + Used to create and initialize to undefined a global var binding in the [[ObjectRecord]] component of a global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a var. The String value N is the bound name. If D is true - the binding may be deleted. Logically equivalent to -CreateMutableBinding followed by a SetMutableBinding but it allows var + the binding may be deleted. Logically equivalent to +CreateMutableBinding followed by a SetMutableBinding but it allows var declarations to receive special treatment. - + CreateGlobalFunctionBinding(N, V, D) - + Create and initialize a global function binding in the [[ObjectRecord]] component of a global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a function. The String value N is the bound name. V is the initialization value. If the Boolean argument D is true - the binding may be deleted. Logically equivalent to -CreateMutableBinding followed by a SetMutableBinding but it allows + the binding may be deleted. Logically equivalent to +CreateMutableBinding followed by a SetMutableBinding but it allows function declarations to receive special treatment. - + @@ -6454,7 +6454,7 @@ function declarations to receive special treatment.

        8.1.1.4.1HasBinding ( N )

        The concrete Environment Record - method HasBinding for global Environment Records simply determines if + method HasBinding for global Environment Records simply determines if the argument identifier is one of the identifiers bound by the record:

        1. Let envRec be the global Environment Record for which the method was invoked.
        2. Let DclRec be envRec.[[DeclarativeRecord]].
        3. If DclRec.HasBinding(N) is true, return true.
        4. Let ObjRec be envRec.[[ObjectRecord]].
        5. Return ? ObjRec.HasBinding(N).
        @@ -6477,8 +6477,8 @@ the argument identifier is one of the identifiers bound by the record:

        8.1.1.4.4InitializeBinding ( N, V )

        The concrete Environment Record - method InitializeBinding for global Environment Records is used to set -the bound value of the current binding of the identifier whose name is + method InitializeBinding for global Environment Records is used to set +the bound value of the current binding of the identifier whose name is the value of the argument N to the value of argument V. An uninitialized binding for N must already exist.

        1. Let envRec be the global Environment Record for which the method was invoked.
        2. Let DclRec be envRec.[[DeclarativeRecord]].
        3. If DclRec.HasBinding(N) is true, then
          1. Return DclRec.InitializeBinding(N, V).
        4. Assert: If the binding exists, it must be in the object Environment Record.
        5. Let ObjRec be envRec.[[ObjectRecord]].
        6. Return ? ObjRec.InitializeBinding(N, V).
        @@ -6487,11 +6487,11 @@ the value of the argument N to the value of argument V. An

        8.1.1.4.5SetMutableBinding ( N, V, S )

        The concrete Environment Record - method SetMutableBinding for global Environment Records attempts to -change the bound value of the current binding of the identifier whose + method SetMutableBinding for global Environment Records attempts to +change the bound value of the current binding of the identifier whose name is the value of the argument N to the value of argument V. If the binding is an immutable binding, a TypeError is thrown if S is true. A property named N - normally already exists but if it does not or is not currently -writable, error handling is determined by the value of the Boolean + normally already exists but if it does not or is not currently +writable, error handling is determined by the value of the Boolean argument S.

        1. Let envRec be the global Environment Record for which the method was invoked.
        2. Let DclRec be envRec.[[DeclarativeRecord]].
        3. If DclRec.HasBinding(N) is true, then
          1. Return DclRec.SetMutableBinding(N, V, S).
        4. Let ObjRec be envRec.[[ObjectRecord]].
        5. Return ? ObjRec.SetMutableBinding(N, V, S).
        @@ -6502,8 +6502,8 @@ argument S.

        The concrete Environment Record method GetBindingValue for global Environment Records returns the value of its bound identifier whose name is the value of the argument N. If the binding is an uninitialized binding throw a ReferenceError exception. A property named N - normally already exists but if it does not or is not currently -writable, error handling is determined by the value of the Boolean + normally already exists but if it does not or is not currently +writable, error handling is determined by the value of the Boolean argument S.

        1. Let envRec be the global Environment Record for which the method was invoked.
        2. Let DclRec be envRec.[[DeclarativeRecord]].
        3. If DclRec.HasBinding(N) is true, then
          1. Return DclRec.GetBindingValue(N, S).
        4. Let ObjRec be envRec.[[ObjectRecord]].
        5. Return ? ObjRec.GetBindingValue(N, S).
        @@ -6512,8 +6512,8 @@ argument S.

        8.1.1.4.7DeleteBinding ( N )

        The concrete Environment Record - method DeleteBinding for global Environment Records can only delete -bindings that have been explicitly designated as being subject to + method DeleteBinding for global Environment Records can only delete +bindings that have been explicitly designated as being subject to deletion.

        1. Let envRec be the global Environment Record for which the method was invoked.
        2. Let DclRec be envRec.[[DeclarativeRecord]].
        3. If DclRec.HasBinding(N) is true, then
          1. Return DclRec.DeleteBinding(N).
        4. Let ObjRec be envRec.[[ObjectRecord]].
        5. Let globalObject be the binding object for ObjRec.
        6. Let existingProp be ? HasOwnProperty(globalObject, N).
        7. If existingProp is true, then
          1. Let status be ? ObjRec.DeleteBinding(N).
          2. If status is true, then
            1. Let varNames be envRec.[[VarNames]].
            2. If N is an element of varNames, remove that element from the varNames.
          3. Return status.
        8. Return true.
        @@ -6547,8 +6547,8 @@ deletion.

        8.1.1.4.12HasVarDeclaration ( N )

        The concrete Environment Record - method HasVarDeclaration for global Environment Records determines if -the argument identifier has a binding in this record that was created + method HasVarDeclaration for global Environment Records determines if +the argument identifier has a binding in this record that was created using a VariableStatement or a FunctionDeclaration:

        1. Let envRec be the global Environment Record for which the method was invoked.
        2. Let varDeclaredNames be envRec.[[VarNames]].
        3. If varDeclaredNames contains N, return true.
        4. Return false.
        @@ -6557,7 +6557,7 @@ using a VariableStateme

        8.1.1.4.13HasLexicalDeclaration ( N )

        The concrete Environment Record - method HasLexicalDeclaration for global Environment Records determines + method HasLexicalDeclaration for global Environment Records determines if the argument identifier has a binding in this record that was created using a lexical declaration such as a LexicalDeclaration or a ClassDeclaration:

        1. Let envRec be the global Environment Record for which the method was invoked.
        2. Let DclRec be envRec.[[DeclarativeRecord]].
        3. Return DclRec.HasBinding(N). @@ -6567,14 +6567,14 @@ if the argument identifier has a binding in this record that was created

          8.1.1.4.14HasRestrictedGlobalProperty ( N )

          The concrete Environment Record - method HasRestrictedGlobalProperty for global Environment Records + method HasRestrictedGlobalProperty for global Environment Records determines if the argument identifier is the name of a property of the global object that must not be shadowed by a global lexical binding:

          1. Let envRec be the global Environment Record for which the method was invoked.
          2. Let ObjRec be envRec.[[ObjectRecord]].
          3. Let globalObject be the binding object for ObjRec.
          4. Let existingProp be ? globalObject.[[GetOwnProperty]](N).
          5. If existingProp is undefined, return false.
          6. If existingProp.[[Configurable]] is true, return false.
          7. Return true.
          Note

          Properties may exist upon a global object - that were directly created rather than being declared using a var or -function declaration. A global lexical binding may not be created that + that were directly created rather than being declared using a var or +function declaration. A global lexical binding may not be created that has the same name as a non-configurable property of the global object. The global property undefined is an example of such a property.

                     @@ -6592,8 +6592,8 @@ has the same name as a non-configurable property of the

          8.1.1.4.16CanDeclareGlobalFunction ( N )

          The concrete Environment Record - method CanDeclareGlobalFunction for global Environment Records -determines if a corresponding CreateGlobalFunctionBinding call would + method CanDeclareGlobalFunction for global Environment Records +determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument N.

          1. Let envRec be the global Environment Record for which the method was invoked.
          2. Let ObjRec be envRec.[[ObjectRecord]].
          3. Let globalObject be the binding object for ObjRec.
          4. Let existingProp be ? globalObject.[[GetOwnProperty]](N).
          5. If existingProp is undefined, return ? IsExtensible(globalObject).
          6. If existingProp.[[Configurable]] is true, return true.
          7. If IsDataDescriptor(existingProp) is true and existingProp has attribute values { [[Writable]]: true, [[Enumerable]]: true }, return true.
          8. Return false.
          @@ -6602,7 +6602,7 @@ succeed if called for the same argument N.

          8.1.1.4.17CreateGlobalVarBinding ( N, D )

          The concrete Environment Record - method CreateGlobalVarBinding for global Environment Records creates + method CreateGlobalVarBinding for global Environment Records creates and initializes a mutable binding in the associated object Environment Record and records the bound name in the associated [[VarNames]] List. If a binding already exists, it is reused and assumed to be initialized.

          1. Let envRec be the global Environment Record for which the method was invoked.
          2. Let ObjRec be envRec.[[ObjectRecord]].
          3. Let globalObject be the binding object for ObjRec.
          4. Let hasProperty be ? HasOwnProperty(globalObject, N).
          5. Let extensible be ? IsExtensible(globalObject).
          6. If hasProperty is false and extensible is true, then
            1. Perform ? ObjRec.CreateMutableBinding(N, D).
            2. Perform ? ObjRec.InitializeBinding(N, undefined).
          7. Let varDeclaredNames be envRec.[[VarNames]].
          8. If varDeclaredNames does not contain N, then
            1. Append N to varDeclaredNames.
          9. Return NormalCompletion(empty).
          @@ -6611,14 +6611,14 @@ and initializes a mutable binding in the associated object

          8.1.1.4.18CreateGlobalFunctionBinding ( N, V, D )

          The concrete Environment Record - method CreateGlobalFunctionBinding for global Environment Records + method CreateGlobalFunctionBinding for global Environment Records creates and initializes a mutable binding in the associated object Environment Record and records the bound name in the associated [[VarNames]] List. If a binding already exists, it is replaced.

          1. Let envRec be the global Environment Record for which the method was invoked.
          2. Let ObjRec be envRec.[[ObjectRecord]].
          3. Let globalObject be the binding object for ObjRec.
          4. Let existingProp be ? globalObject.[[GetOwnProperty]](N).
          5. If existingProp is undefined or existingProp.[[Configurable]] is true, then
            1. Let desc be the PropertyDescriptor { [[Value]]: V, [[Writable]]: true, [[Enumerable]]: true, [[Configurable]]: D }.
          6. Else,
            1. Let desc be the PropertyDescriptor { [[Value]]: V }.
          7. Perform ? DefinePropertyOrThrow(globalObject, N, desc).
          8. Record that the binding for N in ObjRec has been initialized.
          9. Perform ? Set(globalObject, N, V, false).
          10. Let varDeclaredNames be envRec.[[VarNames]].
          11. If varDeclaredNames does not contain N, then
            1. Append N to varDeclaredNames.
          12. Return NormalCompletion(empty).
          Note

          Global function declarations are always represented as own properties of the global object. - If possible, an existing own property is reconfigured to have a -standard set of attribute values. Steps 8-9 are equivalent to what + If possible, an existing own property is reconfigured to have a +standard set of attribute values. Steps 8-9 are equivalent to what calling the InitializeBinding concrete method would do and if globalObject is a Proxy will produce the same sequence of Proxy trap calls.

                     @@ -6627,13 +6627,13 @@ calling the InitializeBinding concrete method would do and if globalObject<

          8.1.1.5Module Environment Records

          A module Environment Record is a declarative Environment Record that is used to represent the outer scope of an ECMAScript Module. - In additional to normal mutable and immutable bindings, module -Environment Records also provide immutable import bindings which are + In additional to normal mutable and immutable bindings, module +Environment Records also provide immutable import bindings which are bindings that provide indirect access to a target binding that exists in another Environment Record.

          Module Environment Records support all of the declarative Environment Record methods listed in Table 14 - and share the same specifications for all of those methods except for -GetBindingValue, DeleteBinding, HasThisBinding and GetThisBinding. In + and share the same specifications for all of those methods except for +GetBindingValue, DeleteBinding, HasThisBinding and GetThisBinding. In addition, module Environment Records support the methods listed in Table 19:

          Table 19: Additional Methods of Module Environment Records
          @@ -6641,38 +6641,38 @@ addition, module Environment Records support the methods listed in
          Method - + Purpose - +
          CreateImportBinding(N, M, N2) - + Create an immutable indirect binding in a module Environment Record. The String value N is the text of the bound name. M is a Module Record, and N2 is a binding that exists in M's module Environment Record. - +
          GetThisBinding() - + Return the value of this Environment Record's this binding. - +
          -

          The behaviour of the additional concrete specification -methods for module Environment Records are defined by the following +

          The behaviour of the additional concrete specification +methods for module Environment Records are defined by the following algorithms:

          @@ -6680,7 +6680,7 @@ algorithms:

          The concrete Environment Record method GetBindingValue for module Environment Records returns the value of its bound identifier whose name is the value of the argument N. - However, if the binding is an indirect binding the value of the target + However, if the binding is an indirect binding the value of the target binding is returned. If the binding exists but is uninitialized a ReferenceError is thrown.

          1. Assert: S is true.
          2. Let envRec be the module Environment Record for which the method was invoked.
          3. Assert: envRec has a binding for N.
          4. If the binding for N is an indirect binding, then
            1. Let M and N2 be the indirection values provided when this binding for N was created.
            2. Let targetEnv be M.[[Environment]].
            3. If targetEnv is undefined, throw a ReferenceError exception.
            4. Let targetER be targetEnv's EnvironmentRecord.
            5. Return ? targetER.GetBindingValue(N2, true).
          5. If the binding for N in envRec is an uninitialized binding, throw a ReferenceError exception.
          6. Return the value currently bound to N in envRec.
          @@ -6779,88 +6779,88 @@ binding is returned. If the binding exists but is uninitialized a Refer Field Name - + Value - + Meaning - + [[Intrinsics]] - + Record whose field names are intrinsic keys and whose values are objects - + The intrinsic values used by code associated with this realm - + [[GlobalObject]] - + Object - + The global object for this realm - + [[GlobalEnv]] - + Lexical Environment - + The global environment for this realm - + [[TemplateMap]] - + A List of Record { [[Site]]: Parse Node, [[Array]]: Object }. - +

          Template objects are canonicalized separately for each realm using its Realm Record's [[TemplateMap]]. Each [[Site]] value is a Parse Node that is a TemplateLiteral. The associated [[Array]] value is the corresponding template object that is passed to a tag function.

          Note
          Once a Parse Node - becomes unreachable, the corresponding [[Array]] is also unreachable, -and it would be unobservable if an implementation removed the pair from + becomes unreachable, the corresponding [[Array]] is also unreachable, +and it would be unobservable if an implementation removed the pair from the [[TemplateMap]] list.
           [[HostDefined]] - + Any, default value is undefined. - + Field reserved for use by host environments that need to associate additional information with a Realm Record. - + @@ -6879,17 +6879,17 @@ the [[TemplateMap]] list.

          The abstract operation CreateIntrinsics with argument realmRec performs the following steps:

          1. Let intrinsics be a new Record.
          2. Set realmRec.[[Intrinsics]] to intrinsics.
          3. Let objProto be ObjectCreate(null).
          4. Set intrinsics.[[%ObjectPrototype%]] to objProto.
          5. Let throwerSteps be the algorithm steps specified in 9.2.9.1 for the %ThrowTypeError% function.
          6. Let thrower be CreateBuiltinFunction(throwerSteps, « », realmRec, null).
          7. Set intrinsics.[[%ThrowTypeError%]] to thrower.
          8. Let noSteps be an empty sequence of algorithm steps.
          9. Let funcProto be CreateBuiltinFunction(noSteps, « », realmRec, objProto).
          10. Set intrinsics.[[%FunctionPrototype%]] to funcProto.
          11. Call thrower.[[SetPrototypeOf]](funcProto).
          12. Perform AddRestrictedFunctionProperties(funcProto, realmRec).
          13. Set fields of intrinsics with the values listed in Table 7 that have not already been handled above. The field names are the names - listed in column one of the table. The value of each field is a new -object value fully and recursively populated with property values as + listed in column one of the table. The value of each field is a new +object value fully and recursively populated with property values as defined by the specification of each object in clauses 18-26. All object - property values are newly created object values. All values that are + property values are newly created object values. All values that are built-in function objects are created by performing CreateBuiltinFunction(<steps>, <slots>, realmRec, - <prototype>) where <steps> is the definition of that -function provided by this specification, <slots> is a list of the -names, if any, of the function's specified internal slots, and + <prototype>) where <steps> is the definition of that +function provided by this specification, <slots> is a list of the +names, if any, of the function's specified internal slots, and <prototype> is the specified value of the function's [[Prototype]] internal slot. The creation of the intrinsics and their properties must - be ordered to avoid any dependencies upon objects that have not yet + be ordered to avoid any dependencies upon objects that have not yet been created.
          14. Return intrinsics.
          @@ -6911,19 +6911,19 @@ been created.
        4. Return intrinsics.

          8.3Execution Contexts

          -

          An execution context is a specification device that -is used to track the runtime evaluation of code by an ECMAScript -implementation. At any point in time, there is at most one execution +

          An execution context is a specification device that +is used to track the runtime evaluation of code by an ECMAScript +implementation. At any point in time, there is at most one execution context per agent that is actually executing code. This is known as the agent's running execution context. All references to the running execution context in this specification denote the running execution context of the surrounding agent.

          The execution context stack is used to track execution contexts. The running execution context - is always the top element of this stack. A new execution context is -created whenever control is transferred from the executable code + is always the top element of this stack. A new execution context is +created whenever control is transferred from the executable code associated with the currently running execution context - to executable code that is not associated with that execution context. + to executable code that is not associated with that execution context. The newly created execution context is pushed onto the stack and becomes the running execution context.

          -

          An execution context contains whatever implementation specific -state is necessary to track the execution progress of its associated +

          An execution context contains whatever implementation specific +state is necessary to track the execution progress of its associated code. Each execution context has at least the state components listed in Table 21.

          Table 21: State Components for All Execution Contexts
          @@ -6932,59 +6932,59 @@ code. Each execution context has at least the state components listed in Component - + Purpose - + code evaluation state - + Any state needed to perform, suspend, and resume evaluation of the code associated with this execution context. - + Function - + If this execution context is evaluating the code of a function object, then the value of this component is that function object. If the context is evaluating the code of a Script or Module, the value is null. - + Realm - + The Realm Record from which associated code accesses ECMAScript resources. - + ScriptOrModule - + The Module Record or Script Record from which associated code originates. If there is no originating script or module, as is the case for the original execution context created in InitializeHostDefinedRealm, the value is null. - +

          Evaluation of code by the running execution context may be suspended at various points defined within this specification. Once the running execution context has been suspended a different execution context may become the running execution context and commence evaluating its code. At some later time a suspended execution context may again become the running execution context and continue evaluating its code at the point where it had previously been suspended. Transition of the running execution context - status among execution contexts usually occurs in stack-like -last-in/first-out manner. However, some ECMAScript features require + status among execution contexts usually occurs in stack-like +last-in/first-out manner. However, some ECMAScript features require non-LIFO transitions of the running execution context.

          The value of the Realm component of the running execution context is also called the current Realm Record. The value of the Function component of the running execution context is also called the active function object.

          Execution contexts for ECMAScript code have the additional state components listed in Table 22.

          @@ -6994,31 +6994,31 @@ non-LIFO transitions of the Lexical Environment used to resolve identifier references made by code within this execution context. - + VariableEnvironment - + Identifies the Lexical Environment whose EnvironmentRecord holds bindings created by VariableStatements within this execution context. - + @@ -7032,33 +7032,33 @@ non-LIFO transitions of the execution context is evaluating. - +

          In most situations only the running execution context (the top of the execution context stack) - is directly manipulated by algorithms within this specification. Hence -when the terms “LexicalEnvironment”, and “VariableEnvironment” are used + is directly manipulated by algorithms within this specification. Hence +when the terms “LexicalEnvironment”, and “VariableEnvironment” are used without qualification they are in reference to those components of the running execution context.

          An execution context is purely a specification mechanism and need - not correspond to any particular artefact of an ECMAScript -implementation. It is impossible for ECMAScript code to directly access + not correspond to any particular artefact of an ECMAScript +implementation. It is impossible for ECMAScript code to directly access or observe an execution context.

          @@ -7072,7 +7072,7 @@ or observe an execution context.

          8.3.2ResolveBinding ( name [ , env ] )

          The ResolveBinding abstract operation is used to determine the binding of name passed as a String value. The optional argument env can be used to explicitly provide the Lexical Environment - that is to be searched for the binding. During execution of ECMAScript + that is to be searched for the binding. During execution of ECMAScript code, ResolveBinding is performed using the following algorithm:

          1. If env is not present or if env is undefined, then
            1. Set env to the running execution context's LexicalEnvironment.
          2. Assert: env is a Lexical Environment.
          3. If the code matching the syntactic production that is being evaluated is contained in strict mode code, let strict be true, else let strict be false.
          4. Return ? GetIdentifierReference(env, name, strict).
          @@ -7115,15 +7115,15 @@ code, ResolveBinding is performed using the following algorithm:

          8.4Jobs and Job Queues

          -

          A Job is an abstract operation that initiates an ECMAScript -computation when no other ECMAScript computation is currently in +

          A Job is an abstract operation that initiates an ECMAScript +computation when no other ECMAScript computation is currently in progress. A Job abstract operation may be defined to accept an arbitrary set of job parameters.

          Execution of a Job can be initiated only when there is no running execution context and the execution context stack is empty. A PendingJob is a request for the future execution of a Job. A PendingJob is an internal Record whose fields are specified in Table 24. - Once execution of a Job is initiated, the Job always executes to -completion. No other Job may be initiated until the currently running + Once execution of a Job is initiated, the Job always executes to +completion. No other Job may be initiated until the currently running Job completes. However, the currently running Job or external events may - cause the enqueuing of additional PendingJobs that may be initiated + cause the enqueuing of additional PendingJobs that may be initiated sometime after completion of the currently running Job.

          Table 24: PendingJob Record Fields
          @@ -7131,96 +7131,96 @@ sometime after completion of the currently running Job.

          Field Name - + Value - + Meaning - +
          [[Job]] - + The name of a Job abstract operation - + This is the abstract operation that is performed when execution of this PendingJob is initiated. - +
          [[Arguments]] - + A List - + The List of argument values that are to be passed to [[Job]] when it is activated. - +
          [[Realm]] - + A Realm Record - + The Realm Record for the initial execution context when this PendingJob is initiated. - +
          [[ScriptOrModule]] - + A Script Record or Module Record - + The script or module for the initial execution context when this PendingJob is initiated. - +
          [[HostDefined]] - + Any, default value is undefined. - + Field reserved for use by host environments that need to associate additional information with a pending Job. - +

          A Job Queue is a FIFO queue of PendingJob records. Each Job Queue - has a name and the full set of available Job Queues are defined by an -ECMAScript implementation. Every ECMAScript implementation has at least + has a name and the full set of available Job Queues are defined by an +ECMAScript implementation. Every ECMAScript implementation has at least the Job Queues defined in Table 25.

          Each agent - has its own set of named Job Queues. All references to a named job + has its own set of named Job Queues. All references to a named job queue in this specification denote the named job queue of the surrounding agent.

          Table 25: Required Job Queues
          @@ -7228,46 +7228,46 @@ queue in this specification denote the named job queue of the Script and Module source text. See clauses 10 and 15. - +
          PromiseJobs - + Jobs that are responses to the settlement of a Promise (see 25.6). - +
          -

          A request for the future execution of a Job is made by -enqueueing, on a Job Queue, a PendingJob record that includes a Job +

          A request for the future execution of a Job is made by +enqueueing, on a Job Queue, a PendingJob record that includes a Job abstract operation name and any necessary argument values. When there is no running execution context and the execution context stack - is empty, the ECMAScript implementation removes the first PendingJob + is empty, the ECMAScript implementation removes the first PendingJob from a Job Queue and uses the information contained in it to create an execution context and starts execution of the associated Job abstract operation.

          -

          The PendingJob records from a single Job Queue are always +

          The PendingJob records from a single Job Queue are always initiated in FIFO order. This specification does not define the order in - which multiple Job Queues are serviced. An ECMAScript implementation -may interweave the FIFO evaluation of the PendingJob records of a Job + which multiple Job Queues are serviced. An ECMAScript implementation +may interweave the FIFO evaluation of the PendingJob records of a Job Queue with the evaluation of the PendingJob records of one or more other Job Queues. An implementation must define what occurs when there are no running execution context and all Job Queues are empty.

          @@ -7276,7 +7276,7 @@ Queue with the evaluation of the PendingJob records of one or more other pre-initialized with at least one PendingJob and one of those Jobs will be the first to be executed. An implementation might choose to free all resources and terminate if the current Job completes and all Job Queues - are empty. Alternatively, it might choose to wait for a some + are empty. Alternatively, it might choose to wait for a some implementation specific agent or mechanism to enqueue new PendingJob requests.

          The following abstract operations are used to create and manage Jobs and Job Queues:

          @@ -7327,8 +7327,8 @@ implementation specific [[LittleEndian]] Boolean The default value computed for the isLittleEndian parameter when it is needed by the algorithms GetValueFromBuffer and SetValueInBuffer. - The choice is implementation-dependent and should be the alternative -that is most efficient for the implementation. Once the value has been + The choice is implementation-dependent and should be the alternative +that is most efficient for the implementation. Once the value has been observed it cannot change. @@ -7363,16 +7363,16 @@ observed it cannot change.

          Once the values of [[Signifier]], [[IsLockFree1]], and [[IsLockFree2]] have been observed by any agent in the agent cluster they cannot change.

          Note 2
          -

          The values of [[IsLockFree1]] and [[IsLockFree2]] are not -necessarily determined by the hardware, but may also reflect -implementation choices that can vary over time and between ECMAScript +

          The values of [[IsLockFree1]] and [[IsLockFree2]] are not +necessarily determined by the hardware, but may also reflect +implementation choices that can vary over time and between ECMAScript implementations.

          There is no [[IsLockFree4]] property: 4-byte atomic operations are always lock-free.

          -

          In practice, if an atomic operation is implemented with any -type of lock the operation is not lock-free. Lock-free does not imply -wait-free: there is no upper bound on how many machine steps may be +

          In practice, if an atomic operation is implemented with any +type of lock the operation is not lock-free. Lock-free does not imply +wait-free: there is no upper bound on how many machine steps may be required to complete a lock-free atomic operation.

          That an atomic access of size n is lock-free does not imply anything about the (perceived) atomicity of non-atomic accesses of size n, specifically, non-atomic accesses may still be performed as a sequence of several separate memory accesses. See ReadSharedMemory and WriteSharedMemory for details.

          @@ -7396,8 +7396,8 @@ required to complete a lock-free atomic operation.

         Note

        In some environments it may not be reasonable for a given agent - to suspend. For example, in a web browser environment, it may be -reasonable to disallow suspending a document's main event handling + to suspend. For example, in a web browser environment, it may be +reasonable to disallow suspending a document's main event handling thread, while still allowing workers' event handling threads to suspend.

                 @@ -7409,8 +7409,8 @@ thread, while still allowing workers' event handling threads to suspend.

        An agent cluster is a maximal set of agents that can communicate by operating on shared memory.

        Note 1
        -

        Programs within different agents may share memory by -unspecified means. At a minimum, the backing memory for +

        Programs within different agents may share memory by +unspecified means. At a minimum, the backing memory for SharedArrayBuffer objects can be shared among the agents in the cluster.

        There may be agents that can communicate by message passing that cannot share memory; they are never in the same agent cluster.

        @@ -7425,8 +7425,8 @@ SharedArrayBuffer objects can be shared among the agents in the cluster.

        All agents within a cluster must have the same value for the [[LittleEndian]] property in their respective Agent Records.

        Note 3
        -

        If different agents within an agent cluster have different -values of [[LittleEndian]] it becomes hard to use shared memory for +

        If different agents within an agent cluster have different +values of [[LittleEndian]] it becomes hard to use shared memory for multi-byte data.

         @@ -7435,38 +7435,38 @@ multi-byte data.

        All agents within a cluster must have different values for the [[Signifier]] property in their respective Agent Records.

        An embedding may deactivate (stop forward progress) or activate (resume forward progress) an agent without the agent's - knowledge or cooperation. If the embedding does so, it must not leave -some agents in the cluster active while other agents in the cluster are + knowledge or cooperation. If the embedding does so, it must not leave +some agents in the cluster active while other agents in the cluster are deactivated indefinitely.

        Note 4

        The purpose of the preceding restriction is to avoid a situation where an agent deadlocks or starves because another agent has been deactivated. For example, if an HTML shared worker that has a - lifetime independent of documents in any windows were allowed to share -memory with the dedicated worker of such an independent document, and -the document and its dedicated worker were to be deactivated while the -dedicated worker holds a lock (say, the document is pushed into its + lifetime independent of documents in any windows were allowed to share +memory with the dedicated worker of such an independent document, and +the document and its dedicated worker were to be deactivated while the +dedicated worker holds a lock (say, the document is pushed into its window's history), and the shared worker then tries to acquire the lock, - then the shared worker will be blocked until the dedicated worker is -activated again, if ever. Meanwhile other workers trying to access the + then the shared worker will be blocked until the dedicated worker is +activated again, if ever. Meanwhile other workers trying to access the shared worker from other windows will starve.

        -

        The implication of the restriction is that it will not be -possible to share memory between agents that don't belong to the same +

        The implication of the restriction is that it will not be +possible to share memory between agents that don't belong to the same suspend/wake collective within the embedding.

        An embedding may terminate an agent without any of the agent's cluster's other agents' prior knowledge or cooperation. If an agent is terminated not by programmatic action of its own or of another agent - in the cluster but by forces external to the cluster, then the -embedding must choose one of two strategies: Either terminate all the + in the cluster but by forces external to the cluster, then the +embedding must choose one of two strategies: Either terminate all the agents in the cluster, or provide reliable APIs that allow the agents in - the cluster to coordinate so that at least one remaining member of the -cluster will be able to detect the termination, with the termination + the cluster to coordinate so that at least one remaining member of the +cluster will be able to detect the termination, with the termination data containing enough information to identify the agent that was terminated.

        Note 5
        -

        Examples of that type of termination are: operating systems or -users terminating agents that are running in separate processes; the +

        Examples of that type of termination are: operating systems or +users terminating agents that are running in separate processes; the embedding itself terminating an agent that is running in-process with the other agents when per-agent resource accounting indicates that the agent is runaway.

         @@ -7477,7 +7477,7 @@ embedding itself terminating an Note 7
        -

        An agent cluster is a specification mechanism and need not +

        An agent cluster is a specification mechanism and need not correspond to any particular artefact of an ECMAScript implementation.

        @@ -7507,24 +7507,24 @@ correspond to any particular artefact of an ECMAScript implementation.

        9.1Ordinary Object Internal Methods and Internal Slots

        All ordinary objects have an internal slot called [[Prototype]]. The value of this internal slot is either null - or an object and is used for implementing inheritance. Data properties -of the [[Prototype]] object are inherited (and visible as properties of -the child object) for the purposes of get access, but not for set -access. Accessor properties are inherited for both get access and set + or an object and is used for implementing inheritance. Data properties +of the [[Prototype]] object are inherited (and visible as properties of +the child object) for the purposes of get access, but not for set +access. Accessor properties are inherited for both get access and set access.

        -

        Every ordinary object has a Boolean-valued [[Extensible]] -internal slot which is used to fulfill the extensibility-related +

        Every ordinary object has a Boolean-valued [[Extensible]] +internal slot which is used to fulfill the extensibility-related internal method invariants specified in 6.1.7.3. Namely, once the value of an object's [[Extensible]] internal slot has been set to false, it is no longer possible to add properties to the object, to modify the - value of the object's [[Prototype]] internal slot, or to subsequently + value of the object's [[Prototype]] internal slot, or to subsequently change the value of [[Extensible]] to true.

        In the following algorithm descriptions, assume O is an ordinary object, P is a property key value, V is any ECMAScript language value, and Desc is a Property Descriptor record.

        -

        Each ordinary object internal method delegates to a -similarly-named abstract operation. If such an abstract operation -depends on another internal method, then the internal method is invoked -on O rather than calling the similarly-named abstract -operation directly. These semantics ensure that exotic objects have -their overridden internal methods invoked when ordinary object internal +

        Each ordinary object internal method delegates to a +similarly-named abstract operation. If such an abstract operation +depends on another internal method, then the internal method is invoked +on O rather than calling the similarly-named abstract +operation directly. These semantics ensure that exotic objects have +their overridden internal methods invoked when ordinary object internal methods are applied to them.

        @@ -7553,9 +7553,9 @@ methods are applied to them.

        1. Assert: Either Type(V) is Object or Type(V) is Null.
        2. Let extensible be O.[[Extensible]].
        3. Let current be O.[[Prototype]].
        4. If SameValue(V, current) is true, return true.
        5. If extensible is false, return false.
        6. Let p be V.
        7. Let done be false.
        8. Repeat, while done is false,
          1. If p is null, set done to true.
          2. Else if SameValue(p, O) is true, return false.
          3. Else,
            1. If p.[[GetPrototypeOf]] is not the ordinary object internal method defined in 9.1.1, set done to true.
            2. Else, set p to p.[[Prototype]].
        9. Set O.[[Prototype]] to V.
        10. Return true.
        Note
        -

        The loop in step 8 guarantees that there will be no +

        The loop in step 8 guarantees that there will be no circularities in any prototype chain that only includes objects that use - the ordinary object definitions for [[GetPrototypeOf]] and + the ordinary object definitions for [[GetPrototypeOf]] and [[SetPrototypeOf]].

                 @@ -7630,11 +7630,11 @@ circularities in any prototype chain that only includes objects that use

        If undefined is passed as O, only validation is performed and no object updates are performed.
        1. Assert: If O is not undefined, then IsPropertyKey(P) is true.
        2. If current is undefined, then
          1. If extensible is false, return false.
          2. Assert: extensible is true.
          3. If IsGenericDescriptor(Desc) is true or IsDataDescriptor(Desc) is true, then
            1. If O is not undefined, create an own data property named P of object O whose [[Value]], [[Writable]], [[Enumerable]] and [[Configurable]] attribute values are described by Desc. If the value of an attribute field of Desc is absent, the attribute of the newly created property is set to its default value.
          4. Else Desc must be an accessor Property Descriptor,
            1. If O is not undefined, create an own accessor property named P of object O whose [[Get]], [[Set]], [[Enumerable]] and [[Configurable]] attribute values are described by Desc. If the value of an attribute field of Desc is absent, the attribute of the newly created property is set to its default value.
          5. Return true.
        3. If every field in Desc is absent, return true.
        4. If current.[[Configurable]] is false, then
          1. If Desc.[[Configurable]] is present and its value is true, return false.
          2. If Desc.[[Enumerable]] is present and the [[Enumerable]] fields of current and Desc are the Boolean negation of each other, return false.
        5. If IsGenericDescriptor(Desc) is true, no further validation is required.
        6. Else if IsDataDescriptor(current) and IsDataDescriptor(Desc) have different results, then
          1. If current.[[Configurable]] is false, return false.
          2. If IsDataDescriptor(current) is true, then
            1. If O is not undefined, convert the property named P of object O from a data property to an accessor property. - Preserve the existing values of the converted property's -[[Configurable]] and [[Enumerable]] attributes and set the rest of the + Preserve the existing values of the converted property's +[[Configurable]] and [[Enumerable]] attributes and set the rest of the property's attributes to their default values.
          3. Else,
            1. If O is not undefined, convert the property named P of object O from an accessor property to a data property. - Preserve the existing values of the converted property's -[[Configurable]] and [[Enumerable]] attributes and set the rest of the + Preserve the existing values of the converted property's +[[Configurable]] and [[Enumerable]] attributes and set the rest of the property's attributes to their default values.
        7. Else if IsDataDescriptor(current) and IsDataDescriptor(Desc) are both true, then
          1. If current.[[Configurable]] is false and current.[[Writable]] is false, then
            1. If Desc.[[Writable]] is present and Desc.[[Writable]] is true, return false.
            2. If Desc.[[Value]] is present and SameValue(Desc.[[Value]], current.[[Value]]) is false, return false.
            3. Return true.
        8. Else IsAccessorDescriptor(current) and IsAccessorDescriptor(Desc) are both true,
          1. If current.[[Configurable]] is false, then
            1. If Desc.[[Set]] is present and SameValue(Desc.[[Set]], current.[[Set]]) is false, return false.
            2. If Desc.[[Get]] is present and SameValue(Desc.[[Get]], current.[[Get]]) is false, return false.
            3. Return true.
        9. If O is not undefined, then
          1. For each field of Desc that is present, set the corresponding attribute of the property named P of object O to the value of the field.
        10. Return true.
        @@ -7733,20 +7733,20 @@ property's attributes to their default values.
  • Else

    9.1.13OrdinaryCreateFromConstructor ( constructor, intrinsicDefaultProto [ , internalSlotsList ] )

    The abstract operation OrdinaryCreateFromConstructor creates an ordinary object whose [[Prototype]] value is retrieved from a constructor's prototype property, if it exists. Otherwise the intrinsic named by intrinsicDefaultProto is used for [[Prototype]]. The optional internalSlotsList is a List of the names of additional internal slots that must be defined as part of the object. If the list is not provided, a new empty List is used. This abstract operation performs the following steps:

    1. Assert: intrinsicDefaultProto - is a String value that is this specification's name of an intrinsic -object. The corresponding object must be an intrinsic that is intended + is a String value that is this specification's name of an intrinsic +object. The corresponding object must be an intrinsic that is intended to be used as the [[Prototype]] value of an object.
    2. Let proto be ? GetPrototypeFromConstructor(constructor, intrinsicDefaultProto).
    3. Return ObjectCreate(proto, internalSlotsList).

    9.1.14GetPrototypeFromConstructor ( constructor, intrinsicDefaultProto )

    -

    The abstract operation GetPrototypeFromConstructor determines -the [[Prototype]] value that should be used to create an object +

    The abstract operation GetPrototypeFromConstructor determines +the [[Prototype]] value that should be used to create an object corresponding to a specific constructor. The value is retrieved from the constructor's prototype property, if it exists. Otherwise the intrinsic named by intrinsicDefaultProto is used for [[Prototype]]. This abstract operation performs the following steps:

    1. Assert: intrinsicDefaultProto - is a String value that is this specification's name of an intrinsic -object. The corresponding object must be an intrinsic that is intended + is a String value that is this specification's name of an intrinsic +object. The corresponding object must be an intrinsic that is intended to be used as the [[Prototype]] value of an object.
    2. Assert: IsCallable(constructor) is true.
    3. Let proto be ? Get(constructor, "prototype").
    4. If Type(proto) is not Object, then
      1. Let realm be ? GetFunctionRealm(constructor).
      2. Set proto to realm's intrinsic object named intrinsicDefaultProto.
    5. Return proto.
    Note
    @@ -7757,10 +7757,10 @@ to be used as the [[Prototype]] value of an object.

  • 9.2ECMAScript Function Objects

    -

    ECMAScript function objects encapsulate parameterized ECMAScript -code closed over a lexical environment and support the dynamic +

    ECMAScript function objects encapsulate parameterized ECMAScript +code closed over a lexical environment and support the dynamic evaluation of that code. An ECMAScript function object - is an ordinary object and has the same internal slots and the same + is an ordinary object and has the same internal slots and the same internal methods as other ordinary objects. The code of an ECMAScript function object may be either strict mode code (10.2.1) or non-strict code. An ECMAScript function object whose code is strict mode code is called a strict function. One whose code is not strict mode code is called a non-strict function.

    ECMAScript function objects have the additional internal slots listed in Table 27.

    Table 27: Internal Slots of ECMAScript Function Objects
    @@ -7769,176 +7769,176 @@ internal methods as other ordinary objects. The code of an ECMAScript Internal Slot - + Type - + Description - + [[Environment]] - + Lexical Environment - + The Lexical Environment that the function was closed over. Used as the outer environment when evaluating the code of the function. - + [[FormalParameters]] - + Parse Node - + The root parse node of the source text that defines the function's formal parameter list. - + [[FunctionKind]] - + String - + Either "normal", "classConstructor", "generator", "async", or "async generator". - + [[ECMAScriptCode]] - + Parse Node - + The root parse node of the source text that defines the function's body. - + [[ConstructorKind]] - + String - + Either "base" or "derived". - + [[Realm]] - + Realm Record - + The realm in which the function was created and which provides any intrinsic objects that are accessed when evaluating the function. - + [[ScriptOrModule]] - + Script Record or Module Record - + The script or module in which the function was created. - + [[ThisMode]] - + (lexical, strict, global) - + Defines how this references are interpreted within the formal parameters and code body of the function. lexical means that this refers to the this value of a lexically enclosing function. strict means that the this value is used exactly as provided by an invocation of the function. global means that a this value of undefined is interpreted as a reference to the global object. - + [[Strict]] - + Boolean - + true if this is a strict function, false if this is a non-strict function. - + [[HomeObject]] - + Object - + If the function uses super, this is the object whose [[GetPrototypeOf]] provides the object where super property lookups begin. - + [[SourceText]] - + String - + The source text that defines the function. - +

    All ECMAScript function objects have the [[Call]] internal method - defined here. ECMAScript functions that are also constructors in + defined here. ECMAScript functions that are also constructors in addition have the [[Construct]] internal method.

    @@ -8076,11 +8076,11 @@ addition have the [[Construct]] internal method.

    9.2.15FunctionDeclarationInstantiation ( func, argumentsList )

    Note 1

    When an execution context is established for evaluating an ECMAScript function a new function Environment Record is created and bindings for each formal parameter are instantiated in that Environment Record. - Each declaration in the function body is also instantiated. If the -function's formal parameters do not include any default value + Each declaration in the function body is also instantiated. If the +function's formal parameters do not include any default value initializers then the body declarations are instantiated in the same Environment Record as the parameters. If default value parameter initializers exist, a second Environment Record - is created for the body declarations. Formal parameters and functions -are initialized as part of FunctionDeclarationInstantiation. All other + is created for the body declarations. Formal parameters and functions +are initialized as part of FunctionDeclarationInstantiation. All other bindings are initialized during evaluation of the function body.

    FunctionDeclarationInstantiation is performed as follows using arguments func and argumentsList. func is the function object for which the execution context is being established.

    @@ -8090,28 +8090,28 @@ bindings are initialized during evaluation of the function body.

    #sec-web-compat-functiondeclarationinstantiation accordingly. -->
    1. Let calleeContext be the running execution context.
    2. Let env be the LexicalEnvironment of calleeContext.
    3. Let envRec be env's EnvironmentRecord.
    4. Let code be func.[[ECMAScriptCode]].
    5. Let strict be func.[[Strict]].
    6. Let formals be func.[[FormalParameters]].
    7. Let parameterNames be the BoundNames of formals.
    8. If parameterNames has any duplicate entries, let hasDuplicates be true. Otherwise, let hasDuplicates be false.
    9. Let simpleParameterList be IsSimpleParameterList of formals.
    10. Let hasParameterExpressions be ContainsExpression of formals.
    11. Let varNames be the VarDeclaredNames of code.
    12. Let varDeclarations be the VarScopedDeclarations of code.
    13. Let lexicalNames be the LexicallyDeclaredNames of code.
    14. Let functionNames be a new empty List.
    15. Let functionsToInitialize be a new empty List.
    16. For each d in varDeclarations, in reverse list order, do
      1. If d is neither a VariableDeclaration nor a ForBinding nor a BindingIdentifier, then
        1. Assert: d is either a FunctionDeclaration, a GeneratorDeclaration, an AsyncFunctionDeclaration, or an AsyncGeneratorDeclaration.
        2. Let fn be the sole element of the BoundNames of d.
        3. If fn is not an element of functionNames, then
          1. Insert fn as the first element of functionNames.
          2. NOTE: If there are multiple function declarations for the same name, the last declaration is used.
          3. Insert d as the first element of functionsToInitialize.
    17. Let argumentsObjectNeeded be true.
    18. If func.[[ThisMode]] is lexical, then
      1. NOTE: Arrow functions never have an arguments objects.
      2. Set argumentsObjectNeeded to false.
    19. Else if "arguments" is an element of parameterNames, then
      1. Set argumentsObjectNeeded to false.
    20. Else if hasParameterExpressions is false, then
      1. If "arguments" is an element of functionNames or if "arguments" is an element of lexicalNames, then
        1. Set argumentsObjectNeeded to false.
    21. For each String paramName in parameterNames, do
      1. Let alreadyDeclared be envRec.HasBinding(paramName).
      2. NOTE: - Early errors ensure that duplicate parameter names can only occur in -non-strict functions that do not have parameter default values or rest + Early errors ensure that duplicate parameter names can only occur in +non-strict functions that do not have parameter default values or rest parameters.
      3. If alreadyDeclared is false, then
        1. Perform ! envRec.CreateMutableBinding(paramName, false).
        2. If hasDuplicates is true, then
          1. Perform ! envRec.InitializeBinding(paramName, undefined).
    22. If argumentsObjectNeeded is true, then
      1. If strict is true or if simpleParameterList is false, then
        1. Let ao be CreateUnmappedArgumentsObject(argumentsList).
      2. Else,
        1. NOTE: - mapped argument object is only provided for non-strict functions that -don't have a rest parameter, any parameter default value initializers, + mapped argument object is only provided for non-strict functions that +don't have a rest parameter, any parameter default value initializers, or any destructured parameters.
        2. Let ao be CreateMappedArgumentsObject(func, formals, argumentsList, envRec).
      3. If strict is true, then
        1. Perform ! envRec.CreateImmutableBinding("arguments", false).
      4. Else,
        1. Perform ! envRec.CreateMutableBinding("arguments", false).
      5. Call envRec.InitializeBinding("arguments", ao).
      6. Let parameterBindings be a new List of parameterNames with "arguments" appended.
    23. Else,
      1. Let parameterBindings be parameterNames.
    24. Let iteratorRecord be CreateListIteratorRecord(argumentsList).
    25. If hasDuplicates is true, then
      1. Perform ? IteratorBindingInitialization for formals with iteratorRecord and undefined as arguments.
    26. Else,
      1. Perform ? IteratorBindingInitialization for formals with iteratorRecord and env as arguments.
    27. If hasParameterExpressions is false, then
      1. NOTE: Only a single lexical environment is needed for the parameters and top-level vars.
      2. Let instantiatedVarNames be a copy of the List parameterBindings.
      3. For each n in varNames, do
        1. If n is not an element of instantiatedVarNames, then
          1. Append n to instantiatedVarNames.
          2. Perform ! envRec.CreateMutableBinding(n, false).
          3. Call envRec.InitializeBinding(n, undefined).
      4. Let varEnv be env.
      5. Let varEnvRec be envRec.
    28. Else,
      1. NOTE: A separate Environment Record - is needed to ensure that closures created by expressions in the formal -parameter list do not have visibility of declarations in the function + is needed to ensure that closures created by expressions in the formal +parameter list do not have visibility of declarations in the function body.
      2. Let varEnv be NewDeclarativeEnvironment(env).
      3. Let varEnvRec be varEnv's EnvironmentRecord.
      4. Set the VariableEnvironment of calleeContext to varEnv.
      5. Let instantiatedVarNames be a new empty List.
      6. For each n in varNames, do
        1. If n is not an element of instantiatedVarNames, then
          1. Append n to instantiatedVarNames.
          2. Perform ! varEnvRec.CreateMutableBinding(n, false).
          3. If n is not an element of parameterBindings or if n is an element of functionNames, let initialValue be undefined.
          4. Else,
            1. Let initialValue be ! envRec.GetBindingValue(n, false).
          5. Call varEnvRec.InitializeBinding(n, initialValue).
          6. NOTE: vars whose names are the same as a formal parameter, initially have the same value as the corresponding initialized parameter.
    29. NOTE: Annex B.3.3.1 adds additional steps at this point.
    30. If strict is false, then
      1. Let lexEnv be NewDeclarativeEnvironment(varEnv).
      2. NOTE: Non-strict functions use a separate lexical Environment Record for top-level lexical declarations so that a direct eval - can determine whether any var scoped declarations introduced by the -eval code conflict with pre-existing top-level lexically scoped + can determine whether any var scoped declarations introduced by the +eval code conflict with pre-existing top-level lexically scoped declarations. This is not needed for strict functions because a strict direct eval always places all declarations into a new Environment Record.
    31. Else, let lexEnv be varEnv.
    32. Let lexEnvRec be lexEnv's EnvironmentRecord.
    33. Set the LexicalEnvironment of calleeContext to lexEnv.
    34. Let lexDeclarations be the LexicallyScopedDeclarations of code.
    35. For each element d in lexDeclarations, do
      1. NOTE: - A lexically declared name cannot be the same as a function/generator -declaration, formal parameter, or a var name. Lexically declared names + A lexically declared name cannot be the same as a function/generator +declaration, formal parameter, or a var name. Lexically declared names are only instantiated here but not initialized.
      2. For each element dn of the BoundNames of d, do
        1. If IsConstantDeclaration of d is true, then
          1. Perform ! lexEnvRec.CreateImmutableBinding(dn, true).
        2. Else,
          1. Perform ! lexEnvRec.CreateMutableBinding(dn, false).
    36. For each Parse Node f in functionsToInitialize, do
      1. Let fn be the sole element of the BoundNames of f.
      2. Let fo be the result of performing InstantiateFunctionObject for f with argument lexEnv.
      3. Perform ! varEnvRec.SetMutableBinding(fn, fo, false).
    37. Return NormalCompletion(empty).
    Note 2

    B.3.3 - provides an extension to the above algorithm that is necessary for -backwards compatibility with web browser implementations of ECMAScript + provides an extension to the above algorithm that is necessary for +backwards compatibility with web browser implementations of ECMAScript that predate ECMAScript 2015.

     Note 3
    @@ -8123,33 +8123,33 @@ that predate ECMAScript 2015.

    9.3Built-in Function Objects

    The built-in function objects defined in this specification may be implemented as either ECMAScript function objects (9.2) - whose behaviour is provided using ECMAScript code or as implementation -provided function exotic objects whose behaviour is provided in some -other manner. In either case, the effect of calling such functions must -conform to their specifications. An implementation may also provide -additional built-in function objects that are not defined in this + whose behaviour is provided using ECMAScript code or as implementation +provided function exotic objects whose behaviour is provided in some +other manner. In either case, the effect of calling such functions must +conform to their specifications. An implementation may also provide +additional built-in function objects that are not defined in this specification.

    If a built-in function object is implemented as an exotic object it must have the ordinary object behaviour specified in 9.1. All such function exotic objects also have [[Prototype]], [[Extensible]], [[Realm]], and [[ScriptOrModule]] internal slots.

    Unless otherwise specified every built-in function object has the %FunctionPrototype% object as the initial value of its [[Prototype]] internal slot.

    -

    The behaviour specified for each built-in function via algorithm +

    The behaviour specified for each built-in function via algorithm steps or other means is the specification of the function body behaviour - for both [[Call]] and [[Construct]] invocations of the function. -However, [[Construct]] invocation is not supported by all built-in -functions. For each built-in function, when invoked with [[Call]], the + for both [[Call]] and [[Construct]] invocations of the function. +However, [[Construct]] invocation is not supported by all built-in +functions. For each built-in function, when invoked with [[Call]], the [[Call]] thisArgument provides the this value, the [[Call]] argumentsList provides the named parameters, and the NewTarget value is undefined. When invoked with [[Construct]], the this value is uninitialized, the [[Construct]] argumentsList provides the named parameters, and the [[Construct]] newTarget parameter provides the NewTarget value. If the built-in function is implemented as an ECMAScript function object - then this specified behaviour must be implemented by the ECMAScript -code that is the body of the function. Built-in functions that are + then this specified behaviour must be implemented by the ECMAScript +code that is the body of the function. Built-in functions that are ECMAScript function objects must be strict functions. If a built-in constructor has any [[Call]] behaviour other than throwing a TypeError exception, an ECMAScript implementation of the function must be done in - a manner that does not cause the function's [[FunctionKind]] internal + a manner that does not cause the function's [[FunctionKind]] internal slot to have the value "classConstructor".

    Built-in function objects that are not identified as constructors - do not implement the [[Construct]] internal method unless otherwise + do not implement the [[Construct]] internal method unless otherwise specified in the description of a particular function. When a built-in constructor is called as part of a new expression the argumentsList parameter of the invoked [[Construct]] internal method provides the values for the built-in constructor's named parameters.

    Built-in functions that are not constructors do not have a prototype property unless otherwise specified in the description of a particular function.

    If a built-in function object - is not implemented as an ECMAScript function it must provide [[Call]] -and [[Construct]] internal methods that conform to the following + is not implemented as an ECMAScript function it must provide [[Call]] +and [[Construct]] internal methods that conform to the following definitions:

    @@ -8180,17 +8180,17 @@ definitions:

    9.4Built-in Exotic Object Internal Methods and Slots

    -

    This specification defines several kinds of built-in exotic -objects. These objects generally behave similar to ordinary objects -except for a few specific situations. The following exotic objects use -the ordinary object internal methods except where it is explicitly +

    This specification defines several kinds of built-in exotic +objects. These objects generally behave similar to ordinary objects +except for a few specific situations. The following exotic objects use +the ordinary object internal methods except where it is explicitly specified otherwise below:

    9.4.1Bound Function Exotic Objects

    A bound function is an exotic object that wraps another function object. A bound function is callable (it has a [[Call]] internal method and may - have a [[Construct]] internal method). Calling a bound function + have a [[Construct]] internal method). Calling a bound function generally results in a call of its wrapped function.

    Bound function objects do not have the internal slots of ECMAScript function objects defined in Table 27. Instead they have the internal slots defined in Table 28.

    Table 28: Internal Slots of Bound Function Exotic Objects
    @@ -8199,57 +8199,57 @@ generally results in a call of its wrapped function.

    Internal Slot - + Type - + Description - + [[BoundTargetFunction]] - + Callable Object - + The wrapped function object. - + [[BoundThis]] - + Any - + The value that is always passed as the this value when calling the wrapped function. - + [[BoundArguments]] - + List of Any - + A list of values whose elements are used as the first arguments to any call to the wrapped function. - + @@ -8282,17 +8282,17 @@ generally results in a call of its wrapped function.

    9.4.2Array Exotic Objects

    An Array object is an exotic object that gives special treatment to array index property keys (see 6.1.7). A property whose property name is an array index is also called an element. Every Array object has a non-configurable "length" property whose value is always a nonnegative integer less than 232. The value of the "length" property is numerically greater than the name of every own property whose name is an array index; - whenever an own property of an Array object is created or changed, -other properties are adjusted as necessary to maintain this invariant. + whenever an own property of an Array object is created or changed, +other properties are adjusted as necessary to maintain this invariant. Specifically, whenever an own property is added whose name is an array index, the value of the "length" property is changed, if necessary, to be one more than the numeric value of that array index; and whenever the value of the "length" property is changed, every own property whose name is an array index - whose value is not smaller than the new length is deleted. This -constraint applies only to own properties of an Array object and is + whose value is not smaller than the new length is deleted. This +constraint applies only to own properties of an Array object and is unaffected by "length" or array index properties that may be inherited from its prototypes.

    Note

    A String property name P is an array index if and only if ToString(ToUint32(P)) is equal to P and ToUint32(P) is not equal to 232 - 1.

     -

    Array exotic objects provide an alternative definition for the -[[DefineOwnProperty]] internal method. Except for that internal method, +

    Array exotic objects provide an alternative definition for the +[[DefineOwnProperty]] internal method. Except for that internal method, Array exotic objects provide all of the other essential internal methods as specified in 9.1.

    @@ -8317,8 +8317,8 @@ Array exotic objects provide all of the other essential internal methods
    • Note

    If originalArray was created using the standard built-in Array constructor for a realm that is not the realm of the running execution context, then a new Array is created using the realm of the running execution context. - This maintains compatibility with Web browsers that have historically -had that behaviour for the Array.prototype methods that now are defined + This maintains compatibility with Web browsers that have historically +had that behaviour for the Array.prototype methods that now are defined using ArraySpeciesCreate.

         @@ -8337,8 +8337,8 @@ using ArraySpeciesCreate.

    9.4.3String Exotic Objects

    A String object is an exotic object - that encapsulates a String value and exposes virtual integer-indexed -data properties corresponding to the individual code unit elements of + that encapsulates a String value and exposes virtual integer-indexed +data properties corresponding to the individual code unit elements of the String value. String exotic objects always have a data property named "length" whose value is the number of code unit elements in the encapsulated String value. Both the code unit data properties and the "length" property are non-writable and non-configurable.

    String exotic objects have the same internal slots as ordinary objects. They also have a [[StringData]] internal slot.

    String exotic objects provide alternative definitions for the following internal methods. All of the other String exotic object essential internal methods that are not defined below are as specified in 9.1.

    @@ -8382,45 +8382,45 @@ the String value. String exotic objects always have a

    9.4.4Arguments Exotic Objects

    Most ECMAScript functions make an arguments object available to - their code. Depending upon the characteristics of the function + their code. Depending upon the characteristics of the function definition, its arguments object is either an ordinary object or an arguments exotic object. An arguments exotic object is an exotic object whose array index properties map to the formal parameters bindings of an invocation of its associated ECMAScript function.

    -

    Arguments exotic objects have the same internal slots as -ordinary objects. They also have a [[ParameterMap]] internal slot. -Ordinary arguments objects also have a [[ParameterMap]] internal slot -whose value is always undefined. For ordinary argument objects the +

    Arguments exotic objects have the same internal slots as +ordinary objects. They also have a [[ParameterMap]] internal slot. +Ordinary arguments objects also have a [[ParameterMap]] internal slot +whose value is always undefined. For ordinary argument objects the [[ParameterMap]] internal slot is only used by Object.prototype.toString (19.1.3.6) to identify them as such.

    Arguments exotic objects provide alternative definitions for the following internal methods. All of the other arguments exotic object essential internal methods that are not defined below are as specified in 9.1

    Note 1

    The integer-indexed data properties of an arguments exotic object whose numeric name values are less than the number of formal parameters of the corresponding function object initially share their values with the corresponding argument bindings in the function's execution context. - This means that changing the property changes the corresponding value + This means that changing the property changes the corresponding value of the argument binding and vice-versa. This correspondence is broken if - such a property is deleted and then redefined or if the property is + such a property is deleted and then redefined or if the property is changed into an accessor property. - If the arguments object is an ordinary object, the values of its + If the arguments object is an ordinary object, the values of its properties are simply a copy of the arguments passed to the function and - there is no dynamic linkage between the property values and the formal + there is no dynamic linkage between the property values and the formal parameter values.

     Note 2

    The ParameterMap object and its property values are used as a - device for specifying the arguments object correspondence to argument + device for specifying the arguments object correspondence to argument bindings. The ParameterMap object and the objects that are the values of - its properties are not directly observable from ECMAScript code. An -ECMAScript implementation does not need to actually create or use such + its properties are not directly observable from ECMAScript code. An +ECMAScript implementation does not need to actually create or use such objects to implement the specified semantics.

     Note 3

    Ordinary arguments objects define a non-configurable accessor property named "callee" which throws a TypeError exception on access. The "callee" - property has a more specific meaning for arguments exotic objects, -which are created only for some class of non-strict functions. The -definition of this property in the ordinary variant exists to ensure -that it is not defined in any other manner by conforming ECMAScript + property has a more specific meaning for arguments exotic objects, +which are created only for some class of non-strict functions. The +definition of this property in the ordinary variant exists to ensure +that it is not defined in any other manner by conforming ECMAScript implementations.

     Note 4

    ECMAScript implementations of arguments exotic objects have historically contained an accessor property named "caller". Prior to ECMAScript 2017, this specification included the definition of a throwing "caller" - property on ordinary arguments objects. Since implementations do not -contain this extension any longer, ECMAScript 2017 dropped the + property on ordinary arguments objects. Since implementations do not +contain this extension any longer, ECMAScript 2017 dropped the requirement for a throwing "caller" accessor.

     @@ -8477,8 +8477,8 @@ requirement for a throwing "caller" accessor.

    The abstract operation MakeArgGetter called with String name and Environment Record env creates a built-in function object that when executed returns the value bound for name in env. It performs the following steps:

    1. Let steps be the steps of an ArgGetter function as specified below.
    2. Let getter be CreateBuiltinFunction(steps, « [[Name]], [[Env]] »).
    3. Set getter.[[Name]] to name.
    4. Set getter.[[Env]] to env.
    5. Return getter.
    -

    An ArgGetter function is an anonymous built-in function -with [[Name]] and [[Env]] internal slots. When an ArgGetter function +

    An ArgGetter function is an anonymous built-in function +with [[Name]] and [[Env]] internal slots. When an ArgGetter function that expects no arguments is called it performs the following steps:

    1. Let f be the active function object.
    2. Let name be f.[[Name]].
    3. Let env be f.[[Env]].
    4. Return env.GetBindingValue(name, false).
    @@ -8492,8 +8492,8 @@ that expects no arguments is called it performs the following steps:

    The abstract operation MakeArgSetter called with String name and Environment Record env creates a built-in function object that when executed sets the value bound for name in env. It performs the following steps:

    1. Let steps be the steps of an ArgSetter function as specified below.
    2. Let setter be CreateBuiltinFunction(steps, « [[Name]], [[Env]] »).
    3. Set setter.[[Name]] to name.
    4. Set setter.[[Env]] to env.
    5. Return setter.
    -

    An ArgSetter function is an anonymous built-in function -with [[Name]] and [[Env]] internal slots. When an ArgSetter function is +

    An ArgSetter function is an anonymous built-in function +with [[Name]] and [[Env]] internal slots. When an ArgSetter function is called with argument value it performs the following steps:

    1. Let f be the active function object.
    2. Let name be f.[[Name]].
    3. Let env be f.[[Env]].
    4. Return env.SetMutableBinding(name, value, false).
    @@ -8508,8 +8508,8 @@ called with argument value it performs the following steps:

    9.4.5Integer-Indexed Exotic Objects

    An Integer-Indexed exotic object is an exotic object that performs special handling of integer index property keys.

    Integer-Indexed exotic objects - have the same internal slots as ordinary objects and additionally -[[ViewedArrayBuffer]], [[ArrayLength]], [[ByteOffset]], and + have the same internal slots as ordinary objects and additionally +[[ViewedArrayBuffer]], [[ArrayLength]], [[ByteOffset]], and [[TypedArrayName]] internal slots.

    Integer-Indexed exotic objects provide alternative definitions for the following internal methods. All of the other Integer-Indexed exotic object essential internal methods that are not defined below are as specified in 9.1.

    @@ -8558,7 +8558,7 @@ called with argument value it performs the following steps:

    9.4.5.7IntegerIndexedObjectCreate ( prototype, internalSlotsList )

    The abstract operation IntegerIndexedObjectCreate with arguments prototype and internalSlotsList is used to specify the creation of new Integer-Indexed exotic objects. The argument internalSlotsList is a List - of the names of additional internal slots that must be defined as part + of the names of additional internal slots that must be defined as part of the object. IntegerIndexedObjectCreate performs the following steps:

    1. Assert: internalSlotsList contains the names [[ViewedArrayBuffer]], [[ArrayLength]], [[ByteOffset]], and [[TypedArrayName]].
    2. Let A be a newly created object with an internal slot for each name in internalSlotsList.
    3. Set A's essential internal methods to the default ordinary object definitions specified in 9.1.
    4. Set A.[[GetOwnProperty]] as specified in 9.4.5.1.
    5. Set A.[[HasProperty]] as specified in 9.4.5.2.
    6. Set A.[[DefineOwnProperty]] as specified in 9.4.5.3.
    7. Set A.[[Get]] as specified in 9.4.5.4.
    8. Set A.[[Set]] as specified in 9.4.5.5.
    9. Set A.[[OwnPropertyKeys]] as specified in 9.4.5.6.
    10. Set A.[[Prototype]] to prototype.
    11. Set A.[[Extensible]] to true.
    12. Return A.
    @@ -8583,7 +8583,7 @@ of the object. IntegerIndexedObjectCreate performs the following steps:

    9.4.6Module Namespace Exotic Objects

    A module namespace object is an exotic object that exposes the bindings exported from an ECMAScript Module (See 15.2.3). There is a one-to-one correspondence between the String-keyed own properties of a module namespace exotic object and the binding names exported by the Module. The exported bindings include any bindings that are indirectly exported using export * export items. Each String-valued own property key is the StringValue of - the corresponding exported binding name. These are the only + the corresponding exported binding name. These are the only String-keyed properties of a module namespace exotic object. Each such property has the attributes { [[Writable]]: true, [[Enumerable]]: true, [[Configurable]]: false }. Module namespace objects are not extensible.

    Module namespace objects have the internal slots defined in Table 29.

    Table 29: Internal Slots of Module Namespace Exotic Objects
    @@ -8592,67 +8592,67 @@ String-keyed properties of a module namespace Internal Slot - + Type - + Description - + [[Module]] - + Module Record - + The Module Record whose exports this namespace exposes. - + [[Exports]] - + List of String - + A List - containing the String values of the exported names exposed as own -properties of this object. The list is ordered as if an Array of those + containing the String values of the exported names exposed as own +properties of this object. The list is ordered as if an Array of those String values had been sorted using Array.prototype.sort using undefined as comparefn. - + [[Prototype]] - + Null - + This slot always contains the value null (see 9.4.6.1). - +

    Module namespace exotic objects provide alternative definitions - for all of the internal methods except [[GetPrototypeOf]], which + for all of the internal methods except [[GetPrototypeOf]], which behaves as defined in 9.1.1.

    @@ -8703,8 +8703,8 @@ behaves as defined in Assert: IsPropertyKey(P) is true.
  • If Type(P) is Symbol, then
    1. Return ? OrdinaryGet(O, P, Receiver).
  • Let exports be O.[[Exports]].
  • If P is not an element of exports, return undefined.
  • Let m be O.[[Module]].
  • Let binding be ! m.ResolveExport(P, « »).
  • Assert: binding is a ResolvedBinding Record.
  • Let targetModule be binding.[[Module]].
  • Assert: targetModule is not undefined.
  • Let targetEnv be targetModule.[[Environment]].
  • If targetEnv is undefined, throw a ReferenceError exception.
  • Let targetEnvRec be targetEnv's EnvironmentRecord.
  • Return ? targetEnvRec.GetBindingValue(binding.[[BindingName]], true).
    • Note
    -

    ResolveExport is idempotent and side-effect free. An -implementation might choose to pre-compute or cache the ResolveExport +

    ResolveExport is idempotent and side-effect free. An +implementation might choose to pre-compute or cache the ResolveExport results for the [[Exports]] of each module namespace exotic object.

         @@ -8743,9 +8743,9 @@ results for the [[Exports]] of each module namespace exotic object that has a [[Prototype]] internal slot that will not change once it is initialized.

    Immutable prototype exotic objects have the same internal slots - as ordinary objects. They are exotic only in the following internal -methods. All other internal methods of immutable prototype exotic -objects that are not explicitly defined below are instead defined as in + as ordinary objects. They are exotic only in the following internal +methods. All other internal methods of immutable prototype exotic +objects that are not explicitly defined below are instead defined as in ordinary objects.

    @@ -8767,13 +8767,13 @@ objects that are not explicitly defined below are instead defined as in

    9.5Proxy Object Internal Methods and Internal Slots

    A proxy object is an exotic object - whose essential internal methods are partially implemented using -ECMAScript code. Every proxy object has an internal slot called + whose essential internal methods are partially implemented using +ECMAScript code. Every proxy object has an internal slot called [[ProxyHandler]]. The value of [[ProxyHandler]] is an object, called the proxy's handler object, or null. Methods (see Table 30) - of a handler object may be used to augment the implementation for one -or more of the proxy object's internal methods. Every proxy object also -has an internal slot called [[ProxyTarget]] whose value is either an + of a handler object may be used to augment the implementation for one +or more of the proxy object's internal methods. Every proxy object also +has an internal slot called [[ProxyTarget]] whose value is either an object or the null value. This object is called the proxy's target object.

    Table 30: Proxy Handler Methods
    @@ -8781,165 +8781,165 @@ object or the null value. This object is called the proxy's
    Internal Method - + Handler Method - +
    [[GetPrototypeOf]] - + getPrototypeOf - +
    [[SetPrototypeOf]] - + setPrototypeOf - +
    [[IsExtensible]] - + isExtensible - +
    [[PreventExtensions]] - + preventExtensions - +
    [[GetOwnProperty]] - + getOwnPropertyDescriptor - +
    [[DefineOwnProperty]] - + defineProperty - +
    [[HasProperty]] - + has - +
    [[Get]] - + get - +
    [[Set]] - + set - +
    [[Delete]] - + deleteProperty - +
    [[OwnPropertyKeys]] - + ownKeys - +
    [[Call]] - + apply - +
    [[Construct]] - + construct - +

    When a handler method is called to provide the implementation of a - proxy object internal method, the handler method is passed the proxy's -target object as a parameter. A proxy's handler object does not -necessarily have a method corresponding to every essential internal -method. Invoking an internal method on the proxy results in the -invocation of the corresponding internal method on the proxy's target + proxy object internal method, the handler method is passed the proxy's +target object as a parameter. A proxy's handler object does not +necessarily have a method corresponding to every essential internal +method. Invoking an internal method on the proxy results in the +invocation of the corresponding internal method on the proxy's target object if the handler object does not have a method corresponding to the internal trap.

    -

    The [[ProxyHandler]] and [[ProxyTarget]] internal slots of a -proxy object are always initialized when the object is created and -typically may not be modified. Some proxy objects are created in a +

    The [[ProxyHandler]] and [[ProxyTarget]] internal slots of a +proxy object are always initialized when the object is created and +typically may not be modified. Some proxy objects are created in a manner that permits them to be subsequently revoked. When a proxy is revoked, its [[ProxyHandler]] and [[ProxyTarget]] internal slots are set to null causing subsequent invocations of internal methods on that proxy object to throw a TypeError exception.

    -

    Because proxy objects permit the implementation of internal -methods to be provided by arbitrary ECMAScript code, it is possible to -define a proxy object whose handler methods violates the invariants +

    Because proxy objects permit the implementation of internal +methods to be provided by arbitrary ECMAScript code, it is possible to +define a proxy object whose handler methods violates the invariants defined in 6.1.7.3. Some of the internal method invariants defined in 6.1.7.3 - are essential integrity invariants. These invariants are explicitly + are essential integrity invariants. These invariants are explicitly enforced by the proxy object internal methods specified in this section. - An ECMAScript implementation must be robust in the presence of all + An ECMAScript implementation must be robust in the presence of all possible invariant violations.

    In the following algorithm descriptions, assume O is an ECMAScript proxy object, P is a property key value, V is any ECMAScript language value and Desc is a Property Descriptor record.

    @@ -8953,13 +8953,13 @@ possible invariant violations.

    • The result of [[GetPrototypeOf]] must be either an Object or null. - +
    • - If the target object is not extensible, [[GetPrototypeOf]] -applied to the proxy object must return the same value as + If the target object is not extensible, [[GetPrototypeOf]] +applied to the proxy object must return the same value as [[GetPrototypeOf]] applied to the proxy object's target object. - +
    @@ -8975,13 +8975,13 @@ applied to the proxy object must return the same value as
    • The result of [[SetPrototypeOf]] is a Boolean value. - +
    • - If the target object is not extensible, the argument value -must be the same as the result of [[GetPrototypeOf]] applied to target + If the target object is not extensible, the argument value +must be the same as the result of [[GetPrototypeOf]] applied to target object. - +
    @@ -8997,13 +8997,13 @@ object.
    • The result of [[IsExtensible]] is a Boolean value. - +
    • [[IsExtensible]] applied to the proxy object must return the - same value as [[IsExtensible]] applied to the proxy object's target + same value as [[IsExtensible]] applied to the proxy object's target object with the same argument. - +
    @@ -9019,11 +9019,11 @@ object with the same argument.
    • The result of [[PreventExtensions]] is a Boolean value. - +
    • [[PreventExtensions]] applied to the proxy object only returns true if [[IsExtensible]] applied to the proxy object's target object is false. - +
    @@ -9039,29 +9039,29 @@ object with the same argument.
    • The result of [[GetOwnProperty]] must be either an Object or undefined. - +
    • A property cannot be reported as non-existent, if it exists as a non-configurable own property of the target object. - +
    • - A property cannot be reported as non-existent, if it exists -as an own property of the target object and the target object is not + A property cannot be reported as non-existent, if it exists +as an own property of the target object and the target object is not extensible. - +
    • - A property cannot be reported as existent, if it does not -exist as an own property of the target object and the target object is + A property cannot be reported as existent, if it does not +exist as an own property of the target object and the target object is not extensible. - +
    • - A property cannot be reported as non-configurable, if it -does not exist as an own property of the target object or if it exists + A property cannot be reported as non-configurable, if it +does not exist as an own property of the target object or if it exists as a configurable own property of the target object. - +
    @@ -9077,20 +9077,20 @@ as a configurable own property of the target object.
    • The result of [[DefineOwnProperty]] is a Boolean value. - +
    • A property cannot be added, if the target object is not extensible. - +
    • A property cannot be non-configurable, unless there exists a corresponding non-configurable own property of the target object. - +
    • If a property has a corresponding target object property then applying the Property Descriptor of the property to the target object using [[DefineOwnProperty]] will not throw an exception. - +
    @@ -9106,17 +9106,17 @@ as a configurable own property of the target object.
    • The result of [[HasProperty]] is a Boolean value. - +
    • A property cannot be reported as non-existent, if it exists as a non-configurable own property of the target object. - +
    • - A property cannot be reported as non-existent, if it exists -as an own property of the target object and the target object is not + A property cannot be reported as non-existent, if it exists +as an own property of the target object and the target object is not extensible. - +
    @@ -9131,14 +9131,14 @@ extensible.

    [[Get]] for proxy objects enforces the following invariants:

    • - The value reported for a property must be the same as the -value of the corresponding target object property if the target object + The value reported for a property must be the same as the +value of the corresponding target object property if the target object property is a non-writable, non-configurable own data property. - +
    • The value reported for a property must be undefined if the corresponding target object property is a non-configurable own accessor property that has undefined as its [[Get]] attribute. - +
    @@ -9154,18 +9154,18 @@ property is a non-writable, non-configurable own data property. - +
  • Cannot set the value of a property if the corresponding target object property is a non-configurable own accessor property that has undefined as its [[Set]] attribute. - +
    • @@ -9181,11 +9181,11 @@ corresponding target object property is a non-writable, non-configurable
    • The result of [[Delete]] is a Boolean value. - +
    • A property cannot be reported as deleted, if it exists as a non-configurable own property of the target object. - +
    @@ -9201,23 +9201,23 @@ corresponding target object property is a non-writable, non-configurable
    • The result of [[OwnPropertyKeys]] is a List. - +
    • The returned List contains no duplicate entries. - +
    • The Type of each result List element is either String or Symbol. - +
    • The result List must contain the keys of all non-configurable own properties of the target object. - +
    • If the target object is not extensible, then the result List must contain all the keys of the own properties of the target object and no other values. - +
    @@ -9230,8 +9230,8 @@ corresponding target object property is a non-writable, non-configurable Note

    A Proxy exotic object - only has a [[Call]] internal method if the initial value of its -[[ProxyTarget]] internal slot is an object that has a [[Call]] internal + only has a [[Call]] internal method if the initial value of its +[[ProxyTarget]] internal slot is an object that has a [[Call]] internal method.

         @@ -9243,8 +9243,8 @@ method.

    Note 1

    A Proxy exotic object - only has a [[Construct]] internal method if the initial value of its -[[ProxyTarget]] internal slot is an object that has a [[Construct]] + only has a [[Construct]] internal method if the initial value of its +[[ProxyTarget]] internal slot is an object that has a [[Construct]] internal method.

     Note 2
    @@ -9252,7 +9252,7 @@ internal method.

    • The result of [[Construct]] must be an Object. - +
    @@ -9276,40 +9276,40 @@ internal method.

    SourceCharacter::any Unicode code point -

    ECMAScript code is expressed using Unicode. ECMAScript source -text is a sequence of code points. All Unicode code point values from +

    ECMAScript code is expressed using Unicode. ECMAScript source +text is a sequence of code points. All Unicode code point values from U+0000 to U+10FFFF, including surrogate code points, may occur in source - text where permitted by the ECMAScript grammars. The actual encodings -used to store and interchange ECMAScript source text is not relevant to -this specification. Regardless of the external source text encoding, a -conforming ECMAScript implementation processes the source text as if it + text where permitted by the ECMAScript grammars. The actual encodings +used to store and interchange ECMAScript source text is not relevant to +this specification. Regardless of the external source text encoding, a +conforming ECMAScript implementation processes the source text as if it was an equivalent sequence of SourceCharacter values, each SourceCharacter - being a Unicode code point. Conforming ECMAScript implementations are -not required to perform any normalization of source text, or behave as + being a Unicode code point. Conforming ECMAScript implementations are +not required to perform any normalization of source text, or behave as though they were performing normalization of source text.

    -

    The components of a combining character sequence are treated as -individual Unicode code points even though a user might think of the +

    The components of a combining character sequence are treated as +individual Unicode code points even though a user might think of the whole sequence as a single character.

    Note
    -

    In string literals, regular expression literals, template -literals and identifiers, any Unicode code point may also be expressed -using Unicode escape sequences that explicitly express a code point's -numeric value. Within a comment, such an escape sequence is effectively +

    In string literals, regular expression literals, template +literals and identifiers, any Unicode code point may also be expressed +using Unicode escape sequences that explicitly express a code point's +numeric value. Within a comment, such an escape sequence is effectively ignored as part of the comment.

    -

    ECMAScript differs from the Java programming language in the +

    ECMAScript differs from the Java programming language in the behaviour of Unicode escape sequences. In a Java program, if the Unicode - escape sequence \u000A, for example, occurs within a -single-line comment, it is interpreted as a line terminator (Unicode -code point U+000A is LINE FEED (LF)) and therefore the next code point + escape sequence \u000A, for example, occurs within a +single-line comment, it is interpreted as a line terminator (Unicode +code point U+000A is LINE FEED (LF)) and therefore the next code point is not part of the comment. Similarly, if the Unicode escape sequence \u000A - occurs within a string literal in a Java program, it is likewise -interpreted as a line terminator, which is not allowed within a string + occurs within a string literal in a Java program, it is likewise +interpreted as a line terminator, which is not allowed within a string literal—one must write \n instead of \u000A to - cause a LINE FEED (LF) to be part of the String value of a string -literal. In an ECMAScript program, a Unicode escape sequence occurring + cause a LINE FEED (LF) to be part of the String value of a string +literal. In an ECMAScript program, a Unicode escape sequence occurring within a comment is never interpreted and therefore cannot contribute to - termination of the comment. Similarly, a Unicode escape sequence -occurring within a string literal in an ECMAScript program always + termination of the comment. Similarly, a Unicode escape sequence +occurring within a string literal in an ECMAScript program always contributes to the literal and is never interpreted as a line terminator or as a code point that might terminate the string literal.

     @@ -9335,24 +9335,24 @@ contributes to the literal and is never interpreted as a line terminator Note
    @@ -9365,29 +9365,29 @@ any source text that is parsed as the function code of a nested Directive Prologue that contains a Use Strict Directive. - +
  • Module code is always strict mode code. - +
  • All parts of a ClassDeclaration or a ClassExpression are strict mode code. - +
  • Eval code is strict mode code if it begins with a Directive Prologue that contains a Use Strict Directive or if the call to eval is a direct eval that is contained in strict mode code. - +
  • Function code is strict mode code if the associated FunctionDeclaration, FunctionExpression, GeneratorDeclaration, GeneratorExpression, AsyncFunctionDeclaration, AsyncFunctionExpression, AsyncGeneratorDeclaration, AsyncGeneratorExpression, MethodDefinition, ArrowFunction, or AsyncArrowFunction is contained in strict mode code or if the code that produces the value of the function's [[ECMAScriptCode]] internal slot begins with a Directive Prologue that contains a Use Strict Directive. - +
  • Function code that is supplied as the arguments to the built-in Function, Generator, AsyncFunction, and AsyncGenerator constructors is strict mode code if the last argument is a String that when processed is a FunctionBody that begins with a Directive Prologue that contains a Use Strict Directive. - +

    • ECMAScript code that is not strict mode code is called non-strict code.

    @@ -9395,12 +9395,12 @@ any source text that is parsed as the function code of a nested

    10.2.2Non-ECMAScript Functions

    -

    An ECMAScript implementation may support the evaluation of -function exotic objects whose evaluative behaviour is expressed in some +

    An ECMAScript implementation may support the evaluation of +function exotic objects whose evaluative behaviour is expressed in some implementation-defined form of executable code other than via ECMAScript code. Whether a function object - is an ECMAScript code function or a non-ECMAScript function is not -semantically observable from the perspective of an ECMAScript code + is an ECMAScript code function or a non-ECMAScript function is not +semantically observable from the perspective of an ECMAScript code function that calls or is called by such a non-ECMAScript function.

    @@ -9410,17 +9410,17 @@ function that calls or is called by such a non-ECMAScript function.

    11ECMAScript Language: Lexical Grammar

    The source text of an ECMAScript Script or Module is first converted into a sequence of input elements, which are tokens, - line terminators, comments, or white space. The source text is scanned -from left to right, repeatedly taking the longest possible sequence of + line terminators, comments, or white space. The source text is scanned +from left to right, repeatedly taking the longest possible sequence of code points as the next input element.

    -

    There are several situations where the identification of lexical -input elements is sensitive to the syntactic grammar context that is -consuming the input elements. This requires multiple goal symbols for +

    There are several situations where the identification of lexical +input elements is sensitive to the syntactic grammar context that is +consuming the input elements. This requires multiple goal symbols for the lexical grammar. The InputElementRegExpOrTemplateTail goal is used in syntactic grammar contexts where a RegularExpressionLiteral, a TemplateMiddle, or a TemplateTail is permitted. The InputElementRegExp goal symbol is used in all syntactic grammar contexts where a RegularExpressionLiteral is permitted but neither a TemplateMiddle, nor a TemplateTail is permitted. The InputElementTemplateTail goal is used in all syntactic grammar contexts where a TemplateMiddle or a TemplateTail is permitted but a RegularExpressionLiteral is not permitted. In all other contexts, InputElementDiv is used as the lexical goal symbol.

    Note
    -

    The use of multiple lexical goals ensures that there are no +

    The use of multiple lexical goals ensures that there are no lexical ambiguities that would affect automatic semicolon insertion. For - example, there are no syntactic grammar contexts where both a leading + example, there are no syntactic grammar contexts where both a leading division or division-assignment, and a leading RegularExpressionLiteral are permitted. This is not affected by semicolon insertion (see 11.9); in examples such as the following:

    a = b
 /hi/g.exec(c).map(d);
    @@ -9463,27 +9463,27 @@ division or division-assignment, and a leading

    11.1Unicode Format-Control Characters

    -

    The Unicode format-control characters (i.e., the characters in -category “Cf” in the Unicode Character Database such as LEFT-TO-RIGHT -MARK or RIGHT-TO-LEFT MARK) are control codes used to control the -formatting of a range of text in the absence of higher-level protocols +

    The Unicode format-control characters (i.e., the characters in +category “Cf” in the Unicode Character Database such as LEFT-TO-RIGHT +MARK or RIGHT-TO-LEFT MARK) are control codes used to control the +formatting of a range of text in the absence of higher-level protocols for this (such as mark-up languages).

    It is useful to allow format-control characters in source text to - facilitate editing and display. All format control characters may be + facilitate editing and display. All format control characters may be used within comments, and within string literals, template literals, and regular expression literals.

    U+200C (ZERO WIDTH NON-JOINER) and U+200D (ZERO WIDTH JOINER) are - format-control characters that are used to make necessary distinctions + format-control characters that are used to make necessary distinctions when forming words or phrases in certain languages. In ECMAScript source text these code points may also be used in an IdentifierName after the first character.

    -

    U+FEFF (ZERO WIDTH NO-BREAK SPACE) is a format-control character +

    U+FEFF (ZERO WIDTH NO-BREAK SPACE) is a format-control character used primarily at the start of a text to mark it as Unicode and to allow - detection of the text's encoding and byte order. <ZWNBSP> + detection of the text's encoding and byte order. <ZWNBSP> characters intended for this purpose can sometimes also appear after the - start of a text, for example as a result of concatenating files. In -ECMAScript source text <ZWNBSP> code points are treated as white + start of a text, for example as a result of concatenating files. In +ECMAScript source text <ZWNBSP> code points are treated as white space characters (see 11.2).

    -

    The special treatment of certain format-control characters +

    The special treatment of certain format-control characters outside of comments, string literals, and regular expression literals is summarized in Table 31.

    Table 31: Format-Control Code Point Usage
    @@ -9492,73 +9492,73 @@ outside of comments, string literals, and regular expression literals is Code Point - + Name - + Abbreviation - + Usage - + U+200C - + ZERO WIDTH NON-JOINER - + <ZWNJ> - + IdentifierPart - + U+200D - + ZERO WIDTH JOINER - + <ZWJ> - + IdentifierPart - + U+FEFF - + ZERO WIDTH NO-BREAK SPACE - + <ZWNBSP> - + WhiteSpace - + @@ -9568,10 +9568,10 @@ outside of comments, string literals, and regular expression literals is

    11.2White Space

    -

    White space code points are used to improve source text +

    White space code points are used to improve source text readability and to separate tokens (indivisible lexical units) from each - other, but are otherwise insignificant. White space code points may -occur between any two tokens and at the start or end of input. White + other, but are otherwise insignificant. White space code points may +occur between any two tokens and at the start or end of input. White space code points may occur within a StringLiteral, a RegularExpressionLiteral, a Template, or a TemplateSubstitutionTail where they are considered significant code points forming part of a literal value. They may also occur within a Comment, but cannot appear within any other kind of token.

    The ECMAScript white space code points are listed in Table 32.

    Table 32: White Space Code Points
    @@ -9580,113 +9580,113 @@ space code points may occur within a WhiteSpace code points listed in the “Space_Separator” (“Zs”) category.

    Note

    Other than for the code points listed in Table 32, ECMAScript WhiteSpace - intentionally excludes all code points that have the Unicode -“White_Space” property but which are not classified in category + intentionally excludes all code points that have the Unicode +“White_Space” property but which are not classified in category “Space_Separator” (“Zs”).

    Syntax

    @@ -9713,13 +9713,13 @@ space code points may occur within a

    11.3Line Terminators

    -

    Like white space code points, line terminator code points are -used to improve source text readability and to separate tokens +

    Like white space code points, line terminator code points are +used to improve source text readability and to separate tokens (indivisible lexical units) from each other. However, unlike white space code points, line terminators have some influence over the behaviour of - the syntactic grammar. In general, line terminators may occur between -any two tokens, but there are a few places where they are forbidden by -the syntactic grammar. Line terminators also affect the process of + the syntactic grammar. In general, line terminators may occur between +any two tokens, but there are a few places where they are forbidden by +the syntactic grammar. Line terminators also affect the process of automatic semicolon insertion (11.9). A line terminator cannot occur within any token except a StringLiteral, Template, or TemplateSubstitutionTail. <LF> and <CR> line terminators cannot occur within a StringLiteral token except as part of a LineContinuation.

    A line terminator can occur within a MultiLineComment but cannot occur within a SingleLineComment.

    Line terminators are included in the set of white space code points that are matched by the \s class in regular expressions.

    @@ -9730,79 +9730,79 @@ automatic semicolon insertion (Table 33 - are treated as line terminators. Other new line or line breaking -Unicode code points are not treated as line terminators but are treated + are treated as line terminators. Other new line or line breaking +Unicode code points are not treated as line terminators but are treated as white space if they meet the requirements listed in Table 32. The sequence <CR><LF> is commonly used as a line terminator. It should be considered a single SourceCharacter for the purpose of reporting line numbers.

    Syntax

    @@ -9824,14 +9824,14 @@ as white space if they meet the requirements listed in 11.4Comments

    Comments can be either single or multi-line. Multi-line comments cannot nest.

    Because a single-line comment can contain any Unicode code point except a LineTerminator - code point, and because of the general rule that a token is always as -long as possible, a single-line comment always consists of all code + code point, and because of the general rule that a token is always as +long as possible, a single-line comment always consists of all code points from the // marker to the end of the line. However, the LineTerminator - at the end of the line is not considered to be part of the single-line -comment; it is recognized separately by the lexical grammar and becomes -part of the stream of input elements for the syntactic grammar. This + at the end of the line is not considered to be part of the single-line +comment; it is recognized separately by the lexical grammar and becomes +part of the stream of input elements for the syntactic grammar. This point is very important, because it implies that the presence or absence - of single-line comments does not affect the process of automatic + of single-line comments does not affect the process of automatic semicolon insertion (see 11.9).

    Comments behave like white space and are discarded except that, if a MultiLineComment contains a line terminator code point, then the entire comment is considered to be a LineTerminator for purposes of parsing by the syntactic grammar.

    Syntax

    @@ -9885,23 +9885,23 @@ semicolon insertion (see

    11.6Names and Keywords

    IdentifierName and ReservedWord - are tokens that are interpreted according to the Default Identifier -Syntax given in Unicode Standard Annex #31, Identifier and Pattern + are tokens that are interpreted according to the Default Identifier +Syntax given in Unicode Standard Annex #31, Identifier and Pattern Syntax, with some small modifications. ReservedWord is an enumerated subset of IdentifierName. The syntactic grammar defines Identifier as an IdentifierName that is not a ReservedWord. - The Unicode identifier grammar is based on character properties -specified by the Unicode Standard. The Unicode code points in the -specified categories in the latest version of the Unicode standard must -be treated as in those categories by all conforming ECMAScript -implementations. ECMAScript implementations may recognize identifier + The Unicode identifier grammar is based on character properties +specified by the Unicode Standard. The Unicode code points in the +specified categories in the latest version of the Unicode standard must +be treated as in those categories by all conforming ECMAScript +implementations. ECMAScript implementations may recognize identifier code points defined in later editions of the Unicode Standard.

    Note 1

    This standard specifies specific code point additions: U+0024 (DOLLAR SIGN) and U+005F (LOW LINE) are permitted anywhere in an IdentifierName, - and the code points U+200C (ZERO WIDTH NON-JOINER) and U+200D (ZERO + and the code points U+200C (ZERO WIDTH NON-JOINER) and U+200D (ZERO WIDTH JOINER) are permitted anywhere after the first code point of an IdentifierName.

    Unicode escape sequences are permitted in an IdentifierName, where they contribute a single Unicode code point to the IdentifierName. The code point is expressed by the CodePoint of the UnicodeEscapeSequence (see 11.8.4). The \ preceding the UnicodeEscapeSequence and the u and { } code units, if they appear, do not contribute code points to the IdentifierName. A UnicodeEscapeSequence cannot be used to put a code point into an IdentifierName that would otherwise be illegal. In other words, if a \ UnicodeEscapeSequence sequence were replaced by the SourceCharacter it contributes, the result must still be a valid IdentifierName that has the exact same sequence of SourceCharacter elements as the original IdentifierName. All interpretations of IdentifierName - within this specification are based upon their actual code points -regardless of whether or not an escape sequence was used to contribute + within this specification are based upon their actual code points +regardless of whether or not an escape sequence was used to contribute any particular code point.

    Two IdentifierNames that are canonically equivalent according to the Unicode standard are not equal unless, after replacement of each UnicodeEscapeSequence, they are represented by the exact same sequence of code points.

    Syntax

    @@ -9933,8 +9933,8 @@ any particular code point.

    The nonterminal IdentifierPart derives _ via UnicodeIDContinue.

     Note 3
    -

    The sets of code points with Unicode properties “ID_Start” and -“ID_Continue” include, respectively, the code points with Unicode +

    The sets of code points with Unicode properties “ID_Start” and +“ID_Continue” include, respectively, the code points with Unicode properties “Other_ID_Start” and “Other_ID_Continue”.

     @@ -9949,7 +9949,7 @@ properties “Other_ID_Start” and “Other_ID_Continue”.

    @@ -9958,7 +9958,7 @@ properties “Other_ID_Start” and “Other_ID_Continue”.

    @@ -10016,15 +10016,15 @@ properties “Other_ID_Start” and “Other_ID_Continue”.

    implements - + package - + protected - + @@ -10032,15 +10032,15 @@ properties “Other_ID_Start” and “Other_ID_Continue”.

    interface - + private - + public - + @@ -10169,135 +10169,135 @@ properties “Other_ID_Start” and “Other_ID_Continue”.

    11.8.3.1Static Semantics: MV

    A numeric literal stands for a value of the Number type. This - value is determined in two steps: first, a mathematical value (MV) is -derived from the literal; second, this mathematical value is rounded as + value is determined in two steps: first, a mathematical value (MV) is +derived from the literal; second, this mathematical value is rounded as described below.

    -

    Once the exact MV for a numeric literal has been determined, -it is then rounded to a value of the Number type. If the MV is 0, then +

    Once the exact MV for a numeric literal has been determined, +it is then rounded to a value of the Number type. If the MV is 0, then the rounded value is +0; otherwise, the rounded value must be the Number value for the MV (as specified in 6.1.6), unless the literal is a DecimalLiteral - and the literal has more than 20 significant digits, in which case the -Number value may be either the Number value for the MV of a literal + and the literal has more than 20 significant digits, in which case the +Number value may be either the Number value for the MV of a literal produced by replacing each significant digit after the 20th with a 0 digit or the Number value for the MV of a literal produced by replacing each significant digit after the 20th with a 0 digit and then incrementing the literal at the 20th significant digit position. A digit is significant if it is not part of an ExponentPart and

    • it is not 0; or - +
    • there is a nonzero digit to its left and there is a nonzero digit, not in the ExponentPart, to its right. - +
    @@ -10563,13 +10563,13 @@ produced by replacing each significant digit after the 20th with a 0A string literal is zero or more Unicode code points enclosed in single or double quotes. Unicode code points may also be represented by an escape sequence. All code points may appear literally in a string - literal except for the closing quote code points, U+005C (REVERSE -SOLIDUS), U+000D (CARRIAGE RETURN), and U+000A (LINE FEED). Any code -points may appear in the form of an escape sequence. String literals -evaluate to ECMAScript String values. When generating these String + literal except for the closing quote code points, U+005C (REVERSE +SOLIDUS), U+000D (CARRIAGE RETURN), and U+000A (LINE FEED). Any code +points may appear in the form of an escape sequence. String literals +evaluate to ECMAScript String values. When generating these String values Unicode code points are UTF-16 encoded as defined in 10.1.1. - Code points belonging to the Basic Multilingual Plane are encoded as a -single code unit element of the string. All other code points are + Code points belonging to the Basic Multilingual Plane are encoded as a +single code unit element of the string. All other code points are encoded as two code unit elements of the string.

    Syntax

    @@ -10636,8 +10636,8 @@ encoded as two code unit elements of the string.

    The definition of the nonterminal HexDigit is given in 11.8.3. SourceCharacter is defined in 10.1.

    Note 2

    <LF> and <CR> cannot appear in a string literal, except as part of a LineContinuation - to produce the empty code points sequence. The proper way to include -either in the String value of a string literal is to use an escape + to produce the empty code points sequence. The proper way to include +either in the String value of a string literal is to use an escape sequence such as \n or \u000A.

     @@ -10654,150 +10654,150 @@ sequence such as \n or \u000A.

    11.8.4.2Static Semantics: SV

    -

    A string literal stands for a value of the String type. The -String value (SV) of the literal is described in terms of code unit -values contributed by the various parts of the string literal. As part -of this process, some Unicode code points within the string literal are -interpreted as having a mathematical value (MV), as described below or +

    A string literal stands for a value of the String type. The +String value (SV) of the literal is described in terms of code unit +values contributed by the various parts of the string literal. As part +of this process, some Unicode code points within the string literal are +interpreted as having a mathematical value (MV), as described below or in 11.8.3.

    Table 34: String Single Character Escape Sequences
    @@ -10806,181 +10806,181 @@ in - + 0x0022 - + QUOTATION MARK - + " - + \' - + 0x0027 - + APOSTROPHE - + ' - + \\ - + 0x005C - + REVERSE SOLIDUS - + \ - + @@ -10991,37 +10991,37 @@ in CharacterEscapeSequence::NonEscapeCharacter is the SV of the NonEscapeCharacter. - +
  • The SV of NonEscapeCharacter::SourceCharacterbut not one of EscapeCharacter or LineTerminator is the UTF16Encoding of the code point value of SourceCharacter. - +
  • The SV of HexEscapeSequence::xHexDigitHexDigit is the code unit whose value is (16 times the MV of the first HexDigit) plus the MV of the second HexDigit. - +
  • The SV of UnicodeEscapeSequence::uHex4Digits is the SV of Hex4Digits. - +
  • The SV of Hex4Digits::HexDigitHexDigitHexDigitHexDigit is the code unit whose value is (0x1000 times the MV of the first HexDigit) plus (0x100 times the MV of the second HexDigit) plus (0x10 times the MV of the third HexDigit) plus the MV of the fourth HexDigit. - +
  • The SV of UnicodeEscapeSequence::u{CodePoint} is the UTF16Encoding of the MV of CodePoint. - +
    • @@ -11034,7 +11034,7 @@ in constructor as a function (see 21.2.3).

    -

    The productions below describe the syntax for a regular +

    The productions below describe the syntax for a regular expression literal and are used by the input element scanner to find the end of the regular expression literal. The source text comprising the RegularExpressionBody and the RegularExpressionFlags are subsequently parsed again using the more stringent ECMAScript Regular Expression grammar (21.2.1).

    An implementation may extend the ECMAScript Regular Expression grammar defined in 21.2.1, but it must not extend the RegularExpressionBody and RegularExpressionFlags productions defined below or the productions used by these productions.

    @@ -11081,7 +11081,7 @@ expression literal and are used by the input element scanner to find the RegularExpressionFlagsIdentifierPart Note 2
    -

    Regular expression literals may not be empty; instead of +

    Regular expression literals may not be empty; instead of representing an empty regular expression literal, the code unit sequence // starts a single-line comment. To specify an empty regular expression, use: /(?:)/.

     @@ -11094,7 +11094,7 @@ representing an empty regular expression literal, the code unit sequence
    • It is a Syntax Error if IdentifierPart contains a Unicode escape sequence. - +
    @@ -11178,382 +11178,382 @@ representing an empty regular expression literal, the code unit sequence

    11.8.6.1Static Semantics: TV and TRV

    -

    A template literal component is interpreted as a sequence of -Unicode code points. The Template Value (TV) of a literal component is +

    A template literal component is interpreted as a sequence of +Unicode code points. The Template Value (TV) of a literal component is described in terms of code unit values (SV, 11.8.4) - contributed by the various parts of the template literal component. As -part of this process, some Unicode code points within the template + contributed by the various parts of the template literal component. As +part of this process, some Unicode code points within the template component are interpreted as having a mathematical value (MV, 11.8.3). - In determining a TV, escape sequences are replaced by the UTF-16 code -unit(s) of the Unicode code point represented by the escape sequence. -The Template Raw Value (TRV) is similar to a Template Value with the + In determining a TV, escape sequences are replaced by the UTF-16 code +unit(s) of the Unicode code point represented by the escape sequence. +The Template Raw Value (TRV) is similar to a Template Value with the difference that in TRVs escape sequences are interpreted literally.

    Note
    @@ -11565,11 +11565,11 @@ unit 0x0075 (LATIN SMALL LETTER U) followed by the code unit 0x007B

    11.9Automatic Semicolon Insertion

    -

    Most ECMAScript statements and declarations must be terminated -with a semicolon. Such semicolons may always appear explicitly in the -source text. For convenience, however, such semicolons may be omitted -from the source text in certain situations. These situations are -described by saying that semicolons are automatically inserted into the +

    Most ECMAScript statements and declarations must be terminated +with a semicolon. Such semicolons may always appear explicitly in the +source text. For convenience, however, such semicolons may be omitted +from the source text in certain situations. These situations are +described by saying that semicolons are automatically inserted into the source code token stream in those situations.

    @@ -11579,45 +11579,45 @@ source code token stream in those situations.

    1. When, as the source text is parsed from left to right, a token (called the offending token) - is encountered that is not allowed by any production of the grammar, + is encountered that is not allowed by any production of the grammar, then a semicolon is automatically inserted before the offending token if one or more of the following conditions is true:

      • The offending token is separated from the previous token by at least one LineTerminator. - +
      • The offending token is }. - +
      • The previous token is ) and the inserted semicolon would then be parsed as the terminating semicolon of a do-while statement (13.7.2). - +
    2. When, as the source text is parsed from left to right, the end - of the input stream of tokens is encountered and the parser is unable -to parse the input token stream as a single instance of the goal -nonterminal, then a semicolon is automatically inserted at the end of + of the input stream of tokens is encountered and the parser is unable +to parse the input token stream as a single instance of the goal +nonterminal, then a semicolon is automatically inserted at the end of the input stream. - +
    3. When, as the source text is parsed from left to right, a token - is encountered that is allowed by some production of the grammar, but + is encountered that is allowed by some production of the grammar, but the production is a restricted production and the token would be the first token for a terminal or nonterminal immediately following the annotation “[no LineTerminator - here]” within the restricted production (and therefore such a token is -called a restricted token), and the restricted token is separated from + here]” within the restricted production (and therefore such a token is +called a restricted token), and the restricted token is separated from the previous token by at least one LineTerminator, then a semicolon is automatically inserted before the restricted token. - +
    -

    However, there is an additional overriding condition on the -preceding rules: a semicolon is never inserted automatically if the -semicolon would then be parsed as an empty statement or if that +

    However, there is an additional overriding condition on the +preceding rules: a semicolon is never inserted automatically if the +semicolon would then be parsed as an empty statement or if that semicolon would become one of the two semicolons in the header of a for statement (see 13.7.4).

    Note

    The following are the only restricted productions in the grammar:

    @@ -11651,26 +11651,26 @@ semicolon would become one of the two semicolons in the header of a for
  • When a ++ or -- token is encountered where the parser would treat it as a postfix operator, and at least one LineTerminator occurred between the preceding token and the ++ or -- token, then a semicolon is automatically inserted before the ++ or -- token. - +
  • When a continue, break, return, throw, or yield token is encountered and a LineTerminator is encountered before the next token, a semicolon is automatically inserted after the continue, break, return, throw, or yield token. - +

    • The resulting practical advice to ECMAScript programmers is:

    • A postfix ++ or -- operator should appear on the same line as its operand. - +
    • An Expression in a return or throw statement or an AssignmentExpression in a yield expression should start on the same line as the return, throw, or yield token. - +
    • A LabelIdentifier in a break or continue statement should be on the same line as the break or continue token. - +
    @@ -11690,8 +11690,8 @@ semicolon would become one of the two semicolons in the header of a forThe source

    for (a; b
 )
    -

    is not a valid ECMAScript sentence and is not altered by -automatic semicolon insertion because the semicolon is needed for the +

    is not a valid ECMAScript sentence and is not altered by +automatic semicolon insertion because the semicolon is needed for the header of a for statement. Automatic semicolon insertion never inserts one of the two semicolons in the header of a for statement.

    The source

    return
@@ -11715,17 +11715,17 @@ a + b;
    if (a > b)
 else c = d

    is not a valid ECMAScript sentence and is not altered by automatic semicolon insertion before the else - token, even though no production of the grammar applies at that point, -because an automatically inserted semicolon would then be parsed as an + token, even though no production of the grammar applies at that point, +because an automatically inserted semicolon would then be parsed as an empty statement.

    The source

    a = b + c
 (d + e).print()
    -

    is not transformed by automatic semicolon insertion, -because the parenthesized expression that begins the second line can be +

    is not transformed by automatic semicolon insertion, +because the parenthesized expression that begins the second line can be interpreted as an argument list for a function call:

    a = b + c(d + e).print()
    -

    In the circumstance that an assignment statement must begin +

    In the circumstance that an assignment statement must begin with a left parenthesis, it is a good idea for the programmer to provide an explicit semicolon at the end of the preceding statement rather than to rely on automatic semicolon insertion.

    @@ -11772,7 +11772,7 @@ with a left parenthesis, it is a good idea for the programmer to provide
    • It is a Syntax Error if the code matched by this production is contained in strict mode code and the StringValue of Identifier is "arguments" or "eval". - +
    @@ -11787,7 +11787,7 @@ with a left parenthesis, it is a good idea for the programmer to provide
    • It is a Syntax Error if the code matched by this production is contained in strict mode code. - +
    @@ -11802,7 +11802,7 @@ with a left parenthesis, it is a good idea for the programmer to provide @@ -11811,7 +11811,7 @@ with a left parenthesis, it is a good idea for the programmer to provide
    • It is a Syntax Error if this production has a [Yield] parameter. - +
    @@ -11820,7 +11820,7 @@ with a left parenthesis, it is a good idea for the programmer to provide
    • It is a Syntax Error if this production has an [Await] parameter. - +
    @@ -11835,11 +11835,11 @@ with a left parenthesis, it is a good idea for the programmer to provide
    • It is a Syntax Error if this production has a [Yield] parameter and StringValue of Identifier is "yield". - +
    • It is a Syntax Error if this production has an [Await] parameter and StringValue of Identifier is "await". - +
    @@ -11848,15 +11848,15 @@ with a left parenthesis, it is a good idea for the programmer to provide
    • It is a Syntax Error if this phrase is contained in strict mode code and the StringValue of IdentifierName is: "implements", "interface", "let", "package", "private", "protected", "public", "static", or "yield". - +
    • It is a Syntax Error if the goal symbol of the syntactic grammar is Module and the StringValue of IdentifierName is "await". - +
    • It is a Syntax Error if StringValue of IdentifierName is the same String value as the StringValue of any ReservedWord except for yield or await. - +
    Note
    @@ -12021,7 +12021,7 @@ with a left parenthesis, it is a good idea for the programmer to provide

    Supplemental Syntax

    When processing an instance of the production - +
    PrimaryExpression[Yield, Await]:CoverParenthesizedExpressionAndArrowParameterList[?Yield, ?Await] @@ -12184,19 +12184,19 @@ with a left parenthesis, it is a good idea for the programmer to provide

    12.2.5Array Initializer

    Note

    An ArrayLiteral - is an expression describing the initialization of an Array object, -using a list, of zero or more expressions each of which represents an -array element, enclosed in square brackets. The elements need not be -literals; they are evaluated each time the array initializer is + is an expression describing the initialization of an Array object, +using a list, of zero or more expressions each of which represents an +array element, enclosed in square brackets. The elements need not be +literals; they are evaluated each time the array initializer is evaluated.

    Array elements may be elided at the beginning, middle or end of - the element list. Whenever a comma in the element list is not preceded + the element list. Whenever a comma in the element list is not preceded by an AssignmentExpression - (i.e., a comma at the beginning or after another comma), the missing -array element contributes to the length of the Array and increases the -index of subsequent elements. Elided array elements are not defined. If -an element is elided at the end of an array, that element does not + (i.e., a comma at the beginning or after another comma), the missing +array element contributes to the length of the Array and increases the +index of subsequent elements. Elided array elements are not defined. If +an element is elided at the end of an array, that element does not contribute to the length of the Array.

    Syntax

    @@ -12263,8 +12263,8 @@ contribute to the length of the Array.

    Note

    CreateDataProperty is used to ensure that own properties are defined for the array even if - the standard built-in Array prototype object has been modified in a -manner that would preclude the creation of new own properties using + the standard built-in Array prototype object has been modified in a +manner that would preclude the creation of new own properties using [[Set]].

     @@ -12292,10 +12292,10 @@ manner that would preclude the creation of new own properties using

    12.2.6Object Initializer

    Note 1
    -

    An object initializer is an expression describing the -initialization of an Object, written in a form resembling a literal. It -is a list of zero or more pairs of property keys and associated values, -enclosed in curly brackets. The values need not be literals; they are +

    An object initializer is an expression describing the +initialization of an Object, written in a form resembling a literal. It +is a list of zero or more pairs of property keys and associated values, +enclosed in curly brackets. The values need not be literals; they are evaluated each time the object initializer is evaluated.

    Syntax

    @@ -12338,8 +12338,8 @@ evaluated each time the object initializer is evaluated.

     Note 3

    In certain contexts, ObjectLiteral is used as a cover grammar for a more restricted secondary grammar. The CoverInitializedName - production is necessary to fully cover these secondary grammars. -However, use of this production results in an early Syntax Error in + production is necessary to fully cover these secondary grammars. +However, use of this production results in an early Syntax Error in normal contexts where an actual ObjectLiteral is expected.

     @@ -12351,7 +12351,7 @@ normal contexts where an actual MethodDefinition is true. - +

    In addition to describing an actual object initializer the ObjectLiteral productions are also used as a cover grammar for ObjectAssignmentPattern and may be recognized as part of a CoverParenthesizedExpressionAndArrowParameterList. When ObjectLiteral appears in a context where ObjectAssignmentPattern is required the following Early Error rules are not applied. In addition, they are not applied when initially parsing a CoverParenthesizedExpressionAndArrowParameterList or CoverCallExpressionAndAsyncArrowHead.

    @@ -12361,7 +12361,7 @@ normal contexts where an actual Note
    @@ -12569,11 +12569,11 @@ normal contexts where an actual RegularExpressionLiteral cannot be recognized using the goal symbol Pattern of the ECMAScript RegExp grammar specified in 21.2.1. - +
  • It is a Syntax Error if FlagText of RegularExpressionLiteral contains any code points other than "g", "i", "m", "s", "u", or "y", or if it contains the same code point more than once. - +
    • @@ -12615,11 +12615,11 @@ normal contexts where an actual TemplateLiteral with argument false is greater than 232 - 1. - +
  • It is a Syntax Error if the [Tagged] parameter was not set and NoSubstitutionTemplate Contains NotEscapeSequence. - +
    • @@ -12629,7 +12629,7 @@ normal contexts where an actual TemplateHead Contains NotEscapeSequence. - + @@ -12639,7 +12639,7 @@ normal contexts where an actual TemplateTail Contains NotEscapeSequence. - + @@ -12650,7 +12650,7 @@ normal contexts where an actual TemplateMiddle Contains NotEscapeSequence. - + @@ -12715,8 +12715,8 @@ normal contexts where an actual Note 2

    Each TemplateLiteral in the program code of a realm is associated with a unique template object that is used in the evaluation of tagged Templates (12.2.9.6). - The template objects are frozen and the same template object is used -each time a specific tagged Template is evaluated. Whether template + The template objects are frozen and the same template object is used +each time a specific tagged Template is evaluated. Whether template objects are created lazily upon first evaluation of the TemplateLiteral or eagerly prior to first evaluation is an implementation choice that is not observable to ECMAScript code.

    Note 3
    @@ -12803,11 +12803,11 @@ objects are created lazily upon first evaluation of the @@ -13068,38 +13068,38 @@ objects are created lazily upon first evaluation of the

    Properties are accessed by name, using either the dot notation:

    MemberExpression . IdentifierName - +
    CallExpression . IdentifierName - +

    or the bracket notation:

    MemberExpression [ Expression ] - +
    CallExpression [ Expression ] - +

    The dot notation is explained by the following syntactic conversion:

    MemberExpression . IdentifierName - +

    is identical in its behaviour to

    MemberExpression [ <identifier-name-string> ] - +

    and similarly

    CallExpression . IdentifierName - +

    is identical in its behaviour to

    CallExpression [ <identifier-name-string> ] - +

    where <identifier-name-string> is the result of evaluating StringValue of IdentifierName.

     @@ -13311,11 +13311,11 @@ objects are created lazily upon first evaluation of the @@ -13326,11 +13326,11 @@ objects are created lazily upon first evaluation of the @@ -13476,11 +13476,11 @@ objects are created lazily upon first evaluation of the It is a Syntax Error if the UnaryExpression is contained in strict mode code and the derived UnaryExpression is PrimaryExpression:IdentifierReference . - +

  • It is a Syntax Error if the derived UnaryExpression is - +
    PrimaryExpression:CoverParenthesizedExpressionAndArrowParameterList @@ -13539,111 +13539,111 @@ objects are created lazily upon first evaluation of the Type of val - + Result - + Undefined - + "undefined" - + Null - + "object" - + Boolean - + "boolean" - + Number - + "number" - + String - + "string" - + Symbol - + "symbol" - + Object (ordinary and does not implement [[Call]]) - + "object" - + Object (standard exotic and does not implement [[Call]]) - + "object" - + Object (implements [[Call]]) - + "function" - + Object (non-standard exotic and does not implement [[Call]]) - + Implementation-defined. Must not be "undefined", "boolean", "function", "number", "symbol", or "string". - + @@ -13757,7 +13757,7 @@ objects are created lazily upon first evaluation of the

    12.6.4Applying the ** Operator

    Returns an implementation-dependent approximation of the result of raising base to the power exponent. - +

    • If exponent is NaN, the result is NaN.
      • @@ -13832,45 +13832,45 @@ objects are created lazily upon first evaluation of the

      12.7.3.1Applying the * Operator

      The * MultiplicativeOperator - performs multiplication, producing the product of its operands. -Multiplication is commutative. Multiplication is not always associative + performs multiplication, producing the product of its operands. +Multiplication is commutative. Multiplication is not always associative in ECMAScript, because of finite precision.

      The result of a floating-point multiplication is governed by the rules of IEEE 754-2008 binary double-precision arithmetic:

      • If either operand is NaN, the result is NaN. - +
      • The sign of the result is positive if both operands have the same sign, negative if the operands have different signs. - +
      • Multiplication of an infinity by a zero results in NaN. - +
      • - Multiplication of an infinity by an infinity results in an + Multiplication of an infinity by an infinity results in an infinity. The sign is determined by the rule already stated above. - +
      • - Multiplication of an infinity by a finite nonzero value + Multiplication of an infinity by a finite nonzero value results in a signed infinity. The sign is determined by the rule already stated above. - +
      • In the remaining cases, where neither an infinity nor NaN - is involved, the product is computed and rounded to the nearest -representable value using IEEE 754-2008 round to nearest, ties to even -mode. If the magnitude is too large to represent, the result is then an -infinity of appropriate sign. If the magnitude is too small to + is involved, the product is computed and rounded to the nearest +representable value using IEEE 754-2008 round to nearest, ties to even +mode. If the magnitude is too large to represent, the result is then an +infinity of appropriate sign. If the magnitude is too small to represent, the result is then a zero of appropriate sign. The ECMAScript - language requires support of gradual underflow as defined by IEEE + language requires support of gradual underflow as defined by IEEE 754-2008. - +
      @@ -13878,60 +13878,60 @@ represent, the result is then a zero of appropriate sign. The ECMAScript

      12.7.3.2Applying the / Operator

      The / MultiplicativeOperator - performs division, producing the quotient of its operands. The left + performs division, producing the quotient of its operands. The left operand is the dividend and the right operand is the divisor. ECMAScript - does not perform integer division. The operands and result of all -division operations are double-precision floating-point numbers. The -result of division is determined by the specification of IEEE 754-2008 + does not perform integer division. The operands and result of all +division operations are double-precision floating-point numbers. The +result of division is determined by the specification of IEEE 754-2008 arithmetic:

      • If either operand is NaN, the result is NaN. - +
      • The sign of the result is positive if both operands have the same sign, negative if the operands have different signs. - +
      • Division of an infinity by an infinity results in NaN. - +
      • Division of an infinity by a zero results in an infinity. The sign is determined by the rule already stated above. - +
      • Division of an infinity by a nonzero finite value results in - a signed infinity. The sign is determined by the rule already stated + a signed infinity. The sign is determined by the rule already stated above. - +
      • Division of a finite value by an infinity results in zero. The sign is determined by the rule already stated above. - +
      • Division of a zero by a zero results in NaN; division of zero by any other finite value results in zero, with the sign determined by the rule already stated above. - +
      • - Division of a nonzero finite value by a zero results in a -signed infinity. The sign is determined by the rule already stated + Division of a nonzero finite value by a zero results in a +signed infinity. The sign is determined by the rule already stated above. - +
      • In the remaining cases, where neither an infinity, nor a zero, nor NaN - is involved, the quotient is computed and rounded to the nearest -representable value using IEEE 754-2008 round to nearest, ties to even -mode. If the magnitude is too large to represent, the operation -overflows; the result is then an infinity of appropriate sign. If the -magnitude is too small to represent, the operation underflows and the -result is a zero of the appropriate sign. The ECMAScript language + is involved, the quotient is computed and rounded to the nearest +representable value using IEEE 754-2008 round to nearest, ties to even +mode. If the magnitude is too large to represent, the operation +overflows; the result is then an infinity of appropriate sign. If the +magnitude is too small to represent, the operation underflows and the +result is a zero of the appropriate sign. The ECMAScript language requires support of gradual underflow as defined by IEEE 754-2008. - +
      @@ -13945,46 +13945,46 @@ requires support of gradual underflow as defined by IEEE 754-2008.

      In C and C++, the remainder operator accepts only integral operands; in ECMAScript, it also accepts floating-point operands.

    • The result of a floating-point remainder operation as computed by the % - operator is not the same as the “remainder” operation defined by IEEE + operator is not the same as the “remainder” operation defined by IEEE 754-2008. The IEEE 754-2008 “remainder” operation computes the remainder - from a rounding division, not a truncating division, and so its -behaviour is not analogous to that of the usual integer remainder -operator. Instead the ECMAScript language defines % on + from a rounding division, not a truncating division, and so its +behaviour is not analogous to that of the usual integer remainder +operator. Instead the ECMAScript language defines % on floating-point operations to behave in a manner analogous to that of the - Java integer remainder operator; this may be compared with the C + Java integer remainder operator; this may be compared with the C library function fmod.

    The result of an ECMAScript floating-point remainder operation is determined by the rules of IEEE arithmetic:

    • If either operand is NaN, the result is NaN. - +
    • The sign of the result equals the sign of the dividend. - +
    • If the dividend is an infinity, or the divisor is a zero, or both, the result is NaN. - +
    • If the dividend is finite and the divisor is an infinity, the result equals the dividend. - +
    • If the dividend is a zero and the divisor is nonzero and finite, the result is the same as the dividend. - +
    • In the remaining cases, where neither an infinity, nor a zero, nor NaN - is involved, the floating-point remainder r from a dividend n and a + is involved, the floating-point remainder r from a dividend n and a divisor d is defined by the mathematical relation r = n - (d × q) where q - is an integer that is negative only if n/d is negative and positive -only if n/d is positive, and whose magnitude is as large as possible -without exceeding the magnitude of the true mathematical quotient of n -and d. r is computed and rounded to the nearest representable value + is an integer that is negative only if n/d is negative and positive +only if n/d is positive, and whose magnitude is as large as possible +without exceeding the magnitude of the true mathematical quotient of n +and d. r is computed and rounded to the nearest representable value using IEEE 754-2008 round to nearest, ties to even mode. - +
    @@ -14037,9 +14037,9 @@ using IEEE 754-2008 round to nearest, ties to even mode. Note 1

    No hint is provided in the calls to ToPrimitive - in steps 5 and 6. All standard objects except Date objects handle the -absence of a hint as if the hint Number were given; Date objects handle -the absence of a hint as if the hint String were given. Exotic objects + in steps 5 and 6. All standard objects except Date objects handle the +absence of a hint as if the hint Number were given; Date objects handle +the absence of a hint as if the hint String were given. Exotic objects may handle the absence of a hint in some other manner.

     Note 2
    @@ -14069,47 +14069,47 @@ may handle the absence of a hint in some other manner.

    • If either operand is NaN, the result is NaN. - +
    • The sum of two infinities of opposite sign is NaN. - +
    • The sum of two infinities of the same sign is the infinity of that sign. - +
    • The sum of an infinity and a finite value is equal to the infinite operand. - +
    • The sum of two negative zeroes is -0. The sum of two positive zeroes, or of two zeroes of opposite sign, is +0. - +
    • The sum of a zero and a nonzero finite value is equal to the nonzero operand. - +
    • The sum of two nonzero finite values of the same magnitude and opposite sign is +0. - +
    • In the remaining cases, where neither an infinity, nor a zero, nor NaN - is involved, and the operands have the same sign or have different + is involved, and the operands have the same sign or have different magnitudes, the sum is computed and rounded to the nearest representable - value using IEEE 754-2008 round to nearest, ties to even mode. If the -magnitude is too large to represent, the operation overflows and the -result is then an infinity of appropriate sign. The ECMAScript language + value using IEEE 754-2008 round to nearest, ties to even mode. If the +magnitude is too large to represent, the operation overflows and the +result is then an infinity of appropriate sign. The ECMAScript language requires support of gradual underflow as defined by IEEE 754-2008. - +
    Note

    The - operator performs subtraction when applied - to two operands of numeric type, producing the difference of its -operands; the left operand is the minuend and the right operand is the + to two operands of numeric type, producing the difference of its +operands; the left operand is the minuend and the right operand is the subtrahend. Given numeric operands a and b, it is always the case that a - b produces the same result as a + (-b).

     @@ -14201,8 +14201,8 @@ subtrahend. Given numeric operands a and b, it is alwa

    12.10Relational Operators

    Note 1
    -

    The result of evaluating a relational operator is always of -type Boolean, reflecting whether the relationship named by the operator +

    The result of evaluating a relational operator is always of +type Boolean, reflecting whether the relationship named by the operator holds between its two operands.

    Syntax

    @@ -14298,7 +14298,7 @@ holds between its two operands.

    12.11Equality Operators

    Note

    The result of evaluating an equality operator is always of type - Boolean, reflecting whether the relationship named by the operator + Boolean, reflecting whether the relationship named by the operator holds between its two operands.

    Syntax

    @@ -14363,15 +14363,15 @@ holds between its two operands.

    • String comparison can be forced by: "" + a == "" + b. - +
    • Numeric comparison can be forced by: +a == +b. - +
    • Boolean comparison can be forced by: !a == !b. - +
    @@ -14380,36 +14380,36 @@ holds between its two operands.

    • A != B is equivalent to !(A == B). - +
    • A == B is equivalent to B == A, except in the order of evaluation of A and B. - +
    Note 3
    -

    The equality operator is not always transitive. For example, -there might be two distinct String objects, each representing the same +

    The equality operator is not always transitive. For example, +there might be two distinct String objects, each representing the same String value; each String object would be considered equal to the String value by the == operator, but the two String objects would not be equal to each other. For example:

    • new String("a") == "a" and "a" == new String("a") are both true. - +
    • new String("a") == new String("a") is false. - +
    Note 4
    -

    Comparison of Strings uses a simple equality test on -sequences of code unit values. There is no attempt to use the more -complex, semantically oriented definitions of character or string -equality and collating order defined in the Unicode specification. -Therefore Strings values that are canonically equal according to the +

    Comparison of Strings uses a simple equality test on +sequences of code unit values. There is no attempt to use the more +complex, semantically oriented definitions of character or string +equality and collating order defined in the Unicode specification. +Therefore Strings values that are canonically equal according to the Unicode standard could test as unequal. In effect this algorithm assumes that both Strings are already in normalized form.

     @@ -14539,8 +14539,8 @@ Unicode standard could test as unequal. In effect this algorithm assumes Note

    The grammar for a ConditionalExpression in ECMAScript is slightly different from that in C and Java, which each allow the second subexpression to be an Expression but restrict the third expression to be a ConditionalExpression. - The motivation for this difference in ECMAScript is to allow an -assignment expression to be governed by either arm of a conditional and + The motivation for this difference in ECMAScript is to allow an +assignment expression to be governed by either arm of a conditional and to eliminate the confusing and fairly useless case of a comma expression as the centre expression.

     @@ -14598,15 +14598,15 @@ to eliminate the confusing and fairly useless case of a comma expression @@ -14615,11 +14615,11 @@ to eliminate the confusing and fairly useless case of a comma expression     @@ -14730,7 +14730,7 @@ to eliminate the confusing and fairly useless case of a comma expression @@ -14739,7 +14739,7 @@ to eliminate the confusing and fairly useless case of a comma expression @@ -14748,11 +14748,11 @@ to eliminate the confusing and fairly useless case of a comma expression @@ -15177,11 +15177,11 @@ to eliminate the confusing and fairly useless case of a comma expression
    • It is a Syntax Error if the LexicallyDeclaredNames of StatementList contains any duplicate entries. - +
    • It is a Syntax Error if any element of the LexicallyDeclaredNames of StatementList also occurs in the VarDeclaredNames of StatementList. - +
    @@ -15319,8 +15319,8 @@ to eliminate the confusing and fairly useless case of a comma expression     , then
    1. Return « ».
  • Return the BoundNames of Declaration.
    • Note
    -

    At the top level of a function, or script, function -declarations are treated like var declarations rather than like lexical +

    At the top level of a function, or script, function +declarations are treated like var declarations rather than like lexical declarations.

     @@ -15485,7 +15485,7 @@ declarations.

    13.2.14Runtime Semantics: BlockDeclarationInstantiation ( code, env )

    Note

    When a Block or CaseBlock is evaluated a new declarative Environment Record - is created and bindings for each block scoped variable, constant, + is created and bindings for each block scoped variable, constant, function, or class declared in the block are instantiated in the Environment Record.

    BlockDeclarationInstantiation is performed as follows using arguments code and env. code is the Parse Node corresponding to the body of the block. env is the Lexical Environment in which bindings are to be created.

    @@ -15532,11 +15532,11 @@ function, or class declared in the block are instantiated in the
  • It is a Syntax Error if the BoundNames of BindingList contains "let". - +
  • It is a Syntax Error if the BoundNames of BindingList contains any duplicate entries. - +
    • @@ -15545,7 +15545,7 @@ function, or class declared in the block are instantiated in the
  • It is a Syntax Error if Initializer is not present and IsConstantDeclaration of the LexicalDeclaration containing this LexicalBinding is true. - +
    • @@ -15963,9 +15963,9 @@ function, or class declared in the block are instantiated in the Note

    When undefined is passed for environment it indicates that a PutValue - operation should be used to assign the initialization value. This is -the case for formal parameter lists of non-strict functions. In that -case the formal parameter bindings are preinitialized in order to deal + operation should be used to assign the initialization value. This is +the case for formal parameter lists of non-strict functions. In that +case the formal parameter bindings are preinitialized in order to deal with the possibility of multiple parameters with the same name.

     @@ -16045,9 +16045,9 @@ with the possibility of multiple parameters with the same name.

    Note

    When undefined is passed for environment it indicates that a PutValue - operation should be used to assign the initialization value. This is -the case for formal parameter lists of non-strict functions. In that -case the formal parameter bindings are preinitialized in order to deal + operation should be used to assign the initialization value. This is +the case for formal parameter lists of non-strict functions. In that +case the formal parameter bindings are preinitialized in order to deal with the possibility of multiple parameters with the same name.

     @@ -16137,9 +16137,9 @@ with the possibility of multiple parameters with the same name.

    With parameters value, environment, and propertyName.

    Note

    When undefined is passed for environment it indicates that a PutValue - operation should be used to assign the initialization value. This is -the case for formal parameter lists of non-strict functions. In that -case the formal parameter bindings are preinitialized in order to deal + operation should be used to assign the initialization value. This is +the case for formal parameter lists of non-strict functions. In that +case the formal parameter bindings are preinitialized in order to deal with the possibility of multiple parameters with the same name.

     @@ -16214,7 +16214,7 @@ with the possibility of multiple parameters with the same name.

    Note
    @@ -16371,7 +16371,7 @@ with the possibility of multiple parameters with the same name.

    Note
    @@ -16537,7 +16537,7 @@ with the possibility of multiple parameters with the same name.

    @@ -16670,20 +16670,20 @@ with the possibility of multiple parameters with the same name.

    If LeftHandSideExpression is either an ObjectLiteral or an ArrayLiteral and if LeftHandSideExpression is covering an AssignmentPattern then the following rules are not applied. Instead, the Early Error rules for AssignmentPattern are used.

    Note
    @@ -16697,15 +16697,15 @@ with the possibility of multiple parameters with the same name.

    • It is a Syntax Error if the BoundNames of ForDeclaration contains "let". - +
    • It is a Syntax Error if any element of the BoundNames of ForDeclaration also occurs in the VarDeclaredNames of Statement. - +
    • It is a Syntax Error if the BoundNames of ForDeclaration contains any duplicate entries. - +
    @@ -16997,30 +16997,30 @@ with the possibility of multiple parameters with the same name.

    13.7.5.15EnumerateObjectProperties ( O )

    When the abstract operation EnumerateObjectProperties is called with argument O, the following steps are taken:

    1. Assert: Type(O) is Object.
    2. Return an Iterator object (25.1.1.2) whose next method iterates over all the String-valued keys of enumerable properties of O. - The iterator object is never directly accessible to ECMAScript code. -The mechanics and order of enumerating the properties is not specified + The iterator object is never directly accessible to ECMAScript code. +The mechanics and order of enumerating the properties is not specified but must conform to the rules specified below.

    The iterator's throw and return methods are null and are never invoked. The iterator's next - method processes object properties to determine whether the property -key should be returned as an iterator value. Returned property keys do -not include keys that are Symbols. Properties of the target object may -be deleted during enumeration. A property that is deleted before it is -processed by the iterator's next method is ignored. If new -properties are added to the target object during enumeration, the newly -added properties are not guaranteed to be processed in the active + method processes object properties to determine whether the property +key should be returned as an iterator value. Returned property keys do +not include keys that are Symbols. Properties of the target object may +be deleted during enumeration. A property that is deleted before it is +processed by the iterator's next method is ignored. If new +properties are added to the target object during enumeration, the newly +added properties are not guaranteed to be processed in the active enumeration. A property name will be returned by the iterator's next method at most once in any enumeration.

    -

    Enumerating the properties of the target object includes -enumerating properties of its prototype, and the prototype of the -prototype, and so on, recursively; but a property of a prototype is not -processed if it has the same name as a property that has already been -processed by the iterator's next method. The values of -[[Enumerable]] attributes are not considered when determining if a -property of a prototype object has already been processed. The -enumerable property names of prototype objects must be obtained by -invoking EnumerateObjectProperties passing the prototype object as the +

    Enumerating the properties of the target object includes +enumerating properties of its prototype, and the prototype of the +prototype, and so on, recursively; but a property of a prototype is not +processed if it has the same name as a property that has already been +processed by the iterator's next method. The values of +[[Enumerable]] attributes are not considered when determining if a +property of a prototype object has already been processed. The +enumerable property names of prototype objects must be obtained by +invoking EnumerateObjectProperties passing the prototype object as the argument. EnumerateObjectProperties must obtain the own property keys of - the target object by calling its [[OwnPropertyKeys]] internal method. + the target object by calling its [[OwnPropertyKeys]] internal method. Property attributes of the target object must be obtained by calling its [[GetOwnProperty]] internal method.

    Note
    @@ -17065,7 +17065,7 @@ Property attributes of the target object must be obtained by calling its @@ -17117,7 +17117,7 @@ Property attributes of the target object must be obtained by calling its @@ -17197,11 +17197,11 @@ Property attributes of the target object must be obtained by calling its Note
    @@ -17304,11 +17304,11 @@ Property attributes of the target object must be obtained by calling its
    • It is a Syntax Error if the LexicallyDeclaredNames of CaseBlock contains any duplicate entries. - +
    • It is a Syntax Error if any element of the LexicallyDeclaredNames of CaseBlock also occurs in the VarDeclaredNames of CaseBlock. - +
    @@ -17628,8 +17628,8 @@ Property attributes of the target object must be obtained by calling its Note

    A Statement may be prefixed by a label. Labelled statements are only used in conjunction with labelled break and continue statements. ECMAScript has no goto statement. A Statement can be part of a LabelledStatement, which itself can be part of a LabelledStatement, - and so on. The labels introduced this way are collectively referred to -as the “current label set” when describing the semantics of individual + and so on. The labels introduced this way are collectively referred to +as the “current label set” when describing the semantics of individual statements.

     @@ -17641,7 +17641,7 @@ statements.

    • It is a Syntax Error if any source text matches this rule. - +
    Note
    @@ -17919,15 +17919,15 @@ statements.

    • It is a Syntax Error if BoundNames of CatchParameter contains any duplicate elements. - +
    • It is a Syntax Error if any element of the BoundNames of CatchParameter also occurs in the LexicallyDeclaredNames of Block. - +
    • It is a Syntax Error if any element of the BoundNames of CatchParameter also occurs in the VarDeclaredNames of Block. - +
    Note
    @@ -18112,8 +18112,8 @@ statements.

    13.16.1Runtime Semantics: Evaluation

    Note

    Evaluating a DebuggerStatement - may allow an implementation to cause a breakpoint when run under a -debugger. If a debugger is not present or active this statement has no + may allow an implementation to cause a breakpoint when run under a +debugger. If a debugger is not present or active this statement has no observable effect.

     @@ -18175,7 +18175,7 @@ observable effect.

    A Directive Prologue may contain more than one Use Strict Directive. However, an implementation may issue a warning if this occurs.

    Note

    The ExpressionStatements of a Directive Prologue - are evaluated normally during evaluation of the containing production. + are evaluated normally during evaluation of the containing production. Implementations may define implementation specific meanings for ExpressionStatements which are not a Use Strict Directive and which occur in a Directive Prologue. If an appropriate notification mechanism exists, an implementation should issue a warning if it encounters in a Directive Prologue an ExpressionStatement that is not a Use Strict Directive and which does not have a meaning defined by the implementation.

     @@ -18196,35 +18196,35 @@ Implementations may define implementation specific meanings for strict mode code, the Early Error rules for UniqueFormalParameters:FormalParameters are applied. - +
  • If the source code matching this production is strict mode code, it is a Syntax Error if BindingIdentifier is present and the StringValue of BindingIdentifier is "eval" or "arguments". - +
  • It is a Syntax Error if ContainsUseStrict of FunctionBody is true and IsSimpleParameterList of FormalParameters is false. - +
  • It is a Syntax Error if any element of the BoundNames of FormalParameters also occurs in the LexicallyDeclaredNames of FunctionBody. - +
  • It is a Syntax Error if FormalParameters Contains SuperProperty is true. - +
  • It is a Syntax Error if FunctionBody Contains SuperProperty is true. - +
  • It is a Syntax Error if FormalParameters Contains SuperCall is true. - +
  • It is a Syntax Error if FunctionBody Contains SuperCall is true. - +
    • Note 1
    @@ -18236,7 +18236,7 @@ Implementations may define implementation specific meanings for FormalParameters contains any duplicate elements. - + @@ -18245,7 +18245,7 @@ Implementations may define implementation specific meanings for FormalParameterList is false and BoundNames of FormalParameterList contains any duplicate elements. - + Note 2
    @@ -18257,23 +18257,23 @@ Implementations may define implementation specific meanings for FunctionStatementList contains any duplicate entries. - +
  • It is a Syntax Error if any element of the LexicallyDeclaredNames of FunctionStatementList also occurs in the VarDeclaredNames of FunctionStatementList. - +
  • It is a Syntax Error if ContainsDuplicateLabels of FunctionStatementList with argument « » is true. - +
  • It is a Syntax Error if ContainsUndefinedBreakTarget of FunctionStatementList with argument « » is true. - +
  • It is a Syntax Error if ContainsUndefinedContinueTarget of FunctionStatementList with arguments « » and « » is true. - +
    • @@ -18293,7 +18293,7 @@ Implementations may define implementation specific meanings for Note

    "*default*" is used within this specification as - a synthetic name for hoistable anonymous functions that are defined + a synthetic name for hoistable anonymous functions that are defined using export declarations.

    @@ -18378,7 +18378,7 @@ using export declarations.

    Note

    The ExpectedArgumentCount of a FormalParameterList is the number of FormalParameters to the left of either the rest parameter or the first FormalParameter with an Initializer. A FormalParameter - without an initializer is allowed after the first parameter with an + without an initializer is allowed after the first parameter with an initializer but such parameters are considered to be optional with undefined as their default value.

     @@ -18546,9 +18546,9 @@ initializer but such parameters are considered to be optional with unde

    With parameters iteratorRecord and environment.

    Note 1

    When undefined is passed for environment it indicates that a PutValue - operation should be used to assign the initialization value. This is -the case for formal parameter lists of non-strict functions. In that -case the formal parameter bindings are preinitialized in order to deal + operation should be used to assign the initialization value. This is +the case for formal parameter lists of non-strict functions. In that +case the formal parameter bindings are preinitialized in order to deal with the possibility of multiple parameters with the same name.

     @@ -18669,7 +18669,7 @@ with the possibility of multiple parameters with the same name.

    Supplemental Syntax

    When the production - +
    ArrowParameters[Yield, Await]:CoverParenthesizedExpressionAndArrowParameterList[?Yield, ?Await] @@ -18688,19 +18688,19 @@ with the possibility of multiple parameters with the same name.

    @@ -18709,11 +18709,11 @@ with the possibility of multiple parameters with the same name.

    @@ -18867,9 +18867,9 @@ with the possibility of multiple parameters with the same name.

    Note

    When undefined is passed for environment it indicates that a PutValue - operation should be used to assign the initialization value. This is -the case for formal parameter lists of non-strict functions. In that -case the formal parameter bindings are preinitialized in order to deal + operation should be used to assign the initialization value. This is +the case for formal parameter lists of non-strict functions. In that +case the formal parameter bindings are preinitialized in order to deal with the possibility of multiple parameters with the same name.

     @@ -18909,8 +18909,8 @@ with the possibility of multiple parameters with the same name.

    Note

    An ArrowFunction does not define local bindings for arguments, super, this, or new.target. Any reference to arguments, super, this, or new.target within an ArrowFunction - must resolve to a binding in a lexically enclosing environment. -Typically this will be the Function Environment of an immediately + must resolve to a binding in a lexically enclosing environment. +Typically this will be the Function Environment of an immediately enclosing function. Even though an ArrowFunction may contain references to super, the function object created in step 4 is not made into a method by performing MakeMethod. An ArrowFunction that references super is always contained within a non-ArrowFunction and the necessary state to implement super is accessible via the scope that is captured by the function object of the ArrowFunction.

     @@ -18939,11 +18939,11 @@ enclosing function. Even though an FunctionBody is true and IsSimpleParameterList of UniqueFormalParameters is false. - +
  • It is a Syntax Error if any element of the BoundNames of UniqueFormalParameters also occurs in the LexicallyDeclaredNames of FunctionBody. - +
    • @@ -18952,15 +18952,15 @@ enclosing function. Even though an PropertySetParameterList contains any duplicate elements. - +
  • It is a Syntax Error if ContainsUseStrict of FunctionBody is true and IsSimpleParameterList of PropertySetParameterList is false. - +
  • It is a Syntax Error if any element of the BoundNames of PropertySetParameterList also occurs in the LexicallyDeclaredNames of FunctionBody. - +
    • @@ -19111,19 +19111,19 @@ enclosing function. Even though an GeneratorMethod is true. - +
  • It is a Syntax Error if UniqueFormalParameters Contains YieldExpression is true. - +
  • It is a Syntax Error if ContainsUseStrict of GeneratorBody is true and IsSimpleParameterList of UniqueFormalParameters is false. - +
  • It is a Syntax Error if any element of the BoundNames of UniqueFormalParameters also occurs in the LexicallyDeclaredNames of GeneratorBody. - +
    • @@ -19140,39 +19140,39 @@ enclosing function. Even though an strict mode code, the Early Error rules for UniqueFormalParameters:FormalParameters are applied. - +
  • If the source code matching this production is strict mode code, it is a Syntax Error if BindingIdentifier is present and the StringValue of BindingIdentifier is "eval" or "arguments". - +
  • It is a Syntax Error if ContainsUseStrict of GeneratorBody is true and IsSimpleParameterList of FormalParameters is false. - +
  • It is a Syntax Error if any element of the BoundNames of FormalParameters also occurs in the LexicallyDeclaredNames of GeneratorBody. - +
  • It is a Syntax Error if FormalParameters Contains YieldExpression is true. - +
  • It is a Syntax Error if FormalParameters Contains SuperProperty is true. - +
  • It is a Syntax Error if GeneratorBody Contains SuperProperty is true. - +
  • It is a Syntax Error if FormalParameters Contains SuperCall is true. - +
  • It is a Syntax Error if GeneratorBody Contains SuperCall is true. - +
    • @@ -19192,7 +19192,7 @@ enclosing function. Even though an Note

    "*default*" is used within this specification as - a synthetic name for hoistable anonymous functions that are defined + a synthetic name for hoistable anonymous functions that are defined using export declarations.

    @@ -19445,7 +19445,7 @@ using export declarations.

    Note

    "*default*" is used within this specification as - a synthetic name for hoistable anonymous functions that are defined + a synthetic name for hoistable anonymous functions that are defined using export declarations.

     @@ -19658,7 +19658,7 @@ using export declarations.

     @@ -19667,11 +19667,11 @@ using export declarations.

    @@ -19680,11 +19680,11 @@ using export declarations.

    @@ -20016,7 +20016,7 @@ using export declarations.

    1. Return « "*default*" ».
    Note
    "*default*" - is used within this specification as a synthetic name for hoistable + is used within this specification as a synthetic name for hoistable anonymous functions that are defined using export declarations.
     @@ -20690,9 +20690,9 @@ anonymous functions that are defined using export declarations.

    A tail position call must either release any transient internal resources associated with the currently executing function execution context before invoking the target function or reuse those resources in support of the target function.

    Note
    -

    For example, a tail position call should only grow an -implementation's activation record stack by the amount that the size of -the target function's activation record exceeds the size of the calling +

    For example, a tail position call should only grow an +implementation's activation record stack by the amount that the size of +the target function's activation record exceeds the size of the calling function's activation record. If the target function's activation record is smaller, then the total size of the stack should decrease.

     @@ -20721,11 +20721,11 @@ function's activation record. If the target function's activation record
    • It is a Syntax Error if the LexicallyDeclaredNames of ScriptBody contains any duplicate entries. - +
    • It is a Syntax Error if any element of the LexicallyDeclaredNames of ScriptBody also occurs in the VarDeclaredNames of ScriptBody. - +
    @@ -20734,23 +20734,23 @@ function's activation record. If the target function's activation record @@ -20827,15 +20827,15 @@ function's activation record. If the target function's activation record Field Name - + Value Type - + Meaning - + @@ -20843,57 +20843,57 @@ function's activation record. If the target function's activation record [[Realm]] - + Realm Record | undefined - + The realm within which this script was created. undefined if not yet assigned. - + [[Environment]] - + Lexical Environment | undefined - + The Lexical Environment containing the top level bindings for this script. This field is set when the script is instantiated. - + [[ECMAScriptCode]] - + a Parse Node - + The result of parsing the source text of this module using Script as the goal symbol. - + [[HostDefined]] - + Any, default value is undefined. - + Field reserved for use by host environments that need to associate additional information with a script. - + @@ -20910,9 +20910,9 @@ function's activation record. If the target function's activation record Note

    An implementation may parse script source text and analyse it - for Early Error conditions prior to evaluation of ParseScript for that -script source text. However, the reporting of any errors must be -deferred until the point where this specification actually performs + for Early Error conditions prior to evaluation of ParseScript for that +script source text. However, the reporting of any errors must be +deferred until the point where this specification actually performs ParseScript upon that source text.

     @@ -20939,11 +20939,11 @@ ParseScript upon that source text.

    Note 2

    Early errors specified in 15.1.1 - prevent name conflicts between function/var declarations and + prevent name conflicts between function/var declarations and let/const/class declarations as well as redeclaration of let/const/class bindings for declaration contained within a single Script. However, such conflicts and redeclarations that span more than one Script - are detected as runtime errors during GlobalDeclarationInstantiation. -If any such errors are detected, no bindings are instantiated for the + are detected as runtime errors during GlobalDeclarationInstantiation. +If any such errors are detected, no bindings are instantiated for the script. However, if the global object is defined using Proxy exotic objects then the runtime tests for conflicting declarations may be unreliable resulting in an abrupt completion and some global declarations not being instantiated. If this occurs, the code for the Script is not evaluated.

    Unlike explicit var or function declarations, properties that are directly created on the global object result in global bindings that may be shadowed by let/const/class declarations.

     @@ -20987,45 +20987,45 @@ script. However, if the
  • It is a Syntax Error if the LexicallyDeclaredNames of ModuleItemList contains any duplicate entries. - +
  • It is a Syntax Error if any element of the LexicallyDeclaredNames of ModuleItemList also occurs in the VarDeclaredNames of ModuleItemList. - +
  • It is a Syntax Error if the ExportedNames of ModuleItemList contains any duplicate entries. - +
  • It is a Syntax Error if any element of the ExportedBindings of ModuleItemList does not also occur in either the VarDeclaredNames of ModuleItemList, or the LexicallyDeclaredNames of ModuleItemList. - +
  • It is a Syntax Error if ModuleItemList Contains super. - +
  • It is a Syntax Error if ModuleItemList Contains NewTarget. - +
  • It is a Syntax Error if ContainsDuplicateLabels of ModuleItemList with argument « » is true. - +
  • It is a Syntax Error if ContainsUndefinedBreakTarget of ModuleItemList with argument « » is true. - +
  • It is a Syntax Error if ContainsUndefinedContinueTarget of ModuleItemList with arguments « » and « » is true. - +
    • Note

    The duplicate ExportedNames rule implies that multiple export default ExportDeclaration items within a ModuleBody - is a Syntax Error. Additional error conditions relating to conflicting -or duplicate declarations are checked during module linking prior to + is a Syntax Error. Additional error conditions relating to conflicting +or duplicate declarations are checked during module linking prior to evaluation of a Module. If any such errors are detected the Module is not evaluated.

     @@ -21301,18 +21301,18 @@ evaluation of a Module

    15.2.1.15Abstract Module Records

    -

    A Module Record encapsulates structural -information about the imports and exports of a single module. This +

    A Module Record encapsulates structural +information about the imports and exports of a single module. This information is used to link the imports and exports of sets of connected - modules. A Module Record includes four fields that are only used when + modules. A Module Record includes four fields that are only used when evaluating a module.

    For specification purposes Module Record values are values of the Record - specification type and can be thought of as existing in a simple -object-oriented hierarchy where Module Record is an abstract class with -both abstract and concrete subclasses. This specification defines the + specification type and can be thought of as existing in a simple +object-oriented hierarchy where Module Record is an abstract class with +both abstract and concrete subclasses. This specification defines the abstract subclass named Cyclic Module Record and its concrete subclass named Source Text Module Record. - Other specifications and implementations may define additional Module -Record subclasses corresponding to alternative module definition + Other specifications and implementations may define additional Module +Record subclasses corresponding to alternative module definition facilities that they defined.

    Module Record defines the fields listed in Table 37. All Module Definition subclasses include at least those fields. Module Record also defines the abstract method list in Table 38. All Module definition subclasses must provide concrete implementations of these abstract methods.

    Table 37: Module Record Fields
    @@ -21321,15 +21321,15 @@ facilities that they defined.

    Field Name - + Value Type - + Meaning - + @@ -21337,57 +21337,57 @@ facilities that they defined.

    [[Realm]] - + Realm Record | undefined - + The Realm within which this module was created. undefined if not yet assigned. - + [[Environment]] - + Lexical Environment | undefined - + The Lexical Environment containing the top level bindings for this module. This field is set when the module is instantiated. - + [[Namespace]] - + Object | undefined - + The Module Namespace Object (26.3) if one has been created for this module. Otherwise undefined. - + [[HostDefined]] - + Any, default value is undefined. - + Field reserved for use by host environments that need to associate additional information with a module. - + @@ -21399,27 +21399,27 @@ facilities that they defined.

    Method - + Purpose - + GetExportedNames(exportStarSet) - + Return a list of all names that are either directly or indirectly exported from this module. - + ResolveExport(exportName, resolveSet) - +

    Return the binding of a name exported by this module. Bindings are represented by a ResolvedBinding Record, of the form { [[Module]]: Module Record, [[BindingName]]: String }. Return null if the name cannot be resolved, or "ambiguous" if multiple bindings were found.

    @@ -21429,7 +21429,7 @@ facilities that they defined.

    Instantiate() - +

    Prepare the module for evaluation by transitively resolving all module dependencies and creating a module Environment Record.

    @@ -21438,12 +21438,12 @@ facilities that they defined.

    Evaluate() - +

    If this module has already been evaluated successfully, return undefined; - if it has already been evaluated unsuccessfully, throw the exception -that was produced. Otherwise, transitively evaluate all module + if it has already been evaluated unsuccessfully, throw the exception +that was produced. Otherwise, transitively evaluate all module dependencies of this module and then evaluate this module.

    Instantiate must have completed successfully prior to invoking this method.

    @@ -21455,8 +21455,8 @@ dependencies of this module and then evaluate this module.

    15.2.1.16Cyclic Module Records

    -

    A Cyclic Module Record -is used to represent information about a module that can participate in +

    A Cyclic Module Record +is used to represent information about a module that can participate in dependency cycles with other modules that are subclasses of the Cyclic Module Record type. Module Records that are not subclasses of the Cyclic Module Record type must not participate in dependency cycles with Source Text Module Records.

    In addition to the fields defined in Table 37 Cyclic Module Records have the additional fields listed in Table 39

    Table 39: Additional Fields of Cyclic Module Records
    @@ -21465,89 +21465,89 @@ dependency cycles with other modules that are subclasses of the . Transitions to "instantiating", "instantiated", "evaluating", "evaluated" (in that order) as the module progresses throughout its lifecycle. - + [[EvaluationError]] - + An abrupt completion | undefined - + A completion of type throw representing the exception that occurred during evaluation. undefined if no exception occurred or if [[Status]] is not "evaluated". - + [[DFSIndex]] - + Integer | undefined - + Auxiliary field used during Instantiate and Evaluate only. If [[Status]] is "instantiating" or "evaluating", this nonnegative number records the point at which the module was first - visited during the ongoing depth-first traversal of the dependency + visited during the ongoing depth-first traversal of the dependency graph. - + [[DFSAncestorIndex]] - + Integer | undefined - + Auxiliary field used during Instantiate and Evaluate only. If [[Status]] is "instantiating" or "evaluating", this is either the module's own [[DFSIndex]] or that of an "earlier" module in the same strongly connected component. - + [[RequestedModules]] - + List of String - + A List of all the ModuleSpecifier strings used by the module represented by this record to request the importation of a module. The List is source code occurrence ordered. - + @@ -21560,31 +21560,31 @@ graph. Method - + Purpose - + InitializeEnvironment() - + Initialize the Lexical Environment of the module, including resolving all imported bindings. - + ExecuteModule() - + Initialize the execution context of the module and evaluate the module's code within it. - + @@ -21607,8 +21607,8 @@ graph.

    The InnerModuleInstantiation abstract operation is used by Instantiate to perform the actual instantiation process for the Cyclic Module Record module, as well as recursively on all other modules in the dependency graph. The stack and index parameters, as well as a module's [[DFSIndex]] and [[DFSAncestorIndex]] - fields, keep track of the depth-first search (DFS) traversal. In -particular, [[DFSAncestorIndex]] is used to discover strongly connected + fields, keep track of the depth-first search (DFS) traversal. In +particular, [[DFSAncestorIndex]] is used to discover strongly connected components (SCCs), such that all modules in an SCC transition to "instantiated" together.

    This abstract operation performs the following steps:

    @@ -21624,8 +21624,8 @@ components (SCCs), such that all modules in an SCC transition to "instanti

    The Evaluate concrete method of a Cyclic Module Record implements the corresponding Module Record abstract method.

    Evaluate transitions this module's [[Status]] from "instantiated" to "evaluated".

    -

    If execution results in an exception, that exception is -recorded in the [[EvaluationError]] field and rethrown by future +

    If execution results in an exception, that exception is +recorded in the [[EvaluationError]] field and rethrown by future invocations of Evaluate.

    This abstract method performs the following steps (most of the work is done by the auxiliary function InnerModuleEvaluation):

    @@ -21641,7 +21641,7 @@ invocations of Evaluate.

    This abstract operation performs the following steps:

    1. If module is not a Cyclic Module Record, then
      1. Perform ? module.Evaluate().
      2. Return index.
    2. If module.[[Status]] is "evaluated", then
      1. If module.[[EvaluationError]] is undefined, return index.
      2. Otherwise return module.[[EvaluationError]].
    3. If module.[[Status]] is "evaluating", return index.
    4. Assert: module.[[Status]] is "instantiated".
    5. Set module.[[Status]] to "evaluating".
    6. Set module.[[DFSIndex]] to index.
    7. Set module.[[DFSAncestorIndex]] to index.
    8. Increase index by 1.
    9. Append module to stack.
    10. For each String required that is an element of module.[[RequestedModules]], do
      1. Let requiredModule be ! HostResolveImportedModule(module, required).
      2. NOTE: - Instantiate must be completed successfully prior to invoking this + Instantiate must be completed successfully prior to invoking this method, so every requested module is guaranteed to resolve successfully.
      3. Set index to ? InnerModuleEvaluation(requiredModule, stack, index).
      4. Assert: requiredModule.[[Status]] is either "evaluating" or "evaluated".
      5. Assert: requiredModule.[[Status]] is "evaluating" if and only if requiredModule is in stack.
      6. If requiredModule.[[Status]] is "evaluating", then
        1. Assert: requiredModule is a Cyclic Module Record.
        2. Set module.[[DFSAncestorIndex]] to min(module.[[DFSAncestorIndex]], requiredModule.[[DFSAncestorIndex]]).
    11. Perform ? module.ExecuteModule().
    12. Assert: module occurs exactly once in stack.
    13. Assert: module.[[DFSAncestorIndex]] is less than or equal to module.[[DFSIndex]].
    14. If module.[[DFSAncestorIndex]] equals module.[[DFSIndex]], then
      1. Let done be false.
      2. Repeat, while done is false,
        1. Let requiredModule be the last element in stack.
        2. Remove the last element of stack.
        3. Set requiredModule.[[Status]] to "evaluated".
        4. If requiredModule and module are the same Module Record, set done to true.
    15. Return index.
    @@ -21650,8 +21650,8 @@ method, so every requested module is guaranteed to resolve successfully.

  • 15.2.1.16.3Example Cyclic Module Record Graphs

    -

    This non-normative section gives a series of examples of -the instantiation and evaluation of a few common module graphs, with a +

    This non-normative section gives a series of examples of +the instantiation and evaluation of a few common module graphs, with a specific focus on how errors can occur.

    First consider the following simple module graph:

    @@ -21661,28 +21661,28 @@ specific focus on how errors can occur.

    • Let's first assume that there are no error conditions. When a host first calls A.Instantiate(), this will complete successfully by assumption, and recursively instantiate modules B and C as well, such that A.[[Status]] = B.[[Status]] = C.[[Status]] = "instantiated". - This preparatory step can be performed at any time. Later, when the -host is ready to incur any possible side effects of the modules, it can + This preparatory step can be performed at any time. Later, when the +host is ready to incur any possible side effects of the modules, it can call A.Evaluate(), which will complete successfully (again by assumption), recursively having evaluated first C and then B. Each module's [[Status]] at this point will be "evaluated".

    Consider then cases involving instantiation errors. If InnerModuleInstantiation of C succeeds but, thereafter, fails for B, for example because it imports something that C does not provide, then the original A.Instantiate() will fail, and both A and B's [[Status]] remain "uninstantiated". C's [[Status]] has become "instantiated", though.

    Finally, consider a case involving evaluation errors. If InnerModuleEvaluation of C succeeds but, thereafter, fails for B, for example because B contains code that throws an exception, then the original A.Evaluate() will fail. The resulting exception will be recorded in both A and B's [[EvaluationError]] fields, and their [[Status]] will become "evaluated". C will also become "evaluated" but, in contrast to A and B, - will remain without an [[EvaluationError]], as it successfully + will remain without an [[EvaluationError]], as it successfully completed evaluation. Storing the exception ensures that any time a host tries to reuse A or B by calling their Evaluate() - method, it will encounter the same exception. (Hosts are not required -to reuse Cyclic Module Records; similarly, hosts are not required to -expose the exception objects thrown by these methods. However, the + method, it will encounter the same exception. (Hosts are not required +to reuse Cyclic Module Records; similarly, hosts are not required to +expose the exception objects thrown by these methods. However, the specification enables such uses.)

    -

    The difference here between instantiation and evaluation -errors is due to how evaluation must be only performed once, as it can -cause side effects; it is thus important to remember whether evaluation -has already been performed, even if unsuccessfully. (In the error case, -it makes sense to also remember the exception because otherwise -subsequent Evaluate() calls would have to synthesize a new one.) -Instantiation, on the other hand, is side-effect-free, and thus even if +

    The difference here between instantiation and evaluation +errors is due to how evaluation must be only performed once, as it can +cause side effects; it is thus important to remember whether evaluation +has already been performed, even if unsuccessfully. (In the error case, +it makes sense to also remember the exception because otherwise +subsequent Evaluate() calls would have to synthesize a new one.) +Instantiation, on the other hand, is side-effect-free, and thus even if it fails, it can be retried at a later time with no issues.

    Now consider a different type of error condition:

    @@ -21692,11 +21692,11 @@ it fails, it can be retried at a later time with no issues.

    In this scenario, module A declares a dependency on some other module, but no Module Record exists for that module, i.e. HostResolveImportedModule - throws an exception when asked for it. This could occur for a variety -of reasons, such as the corresponding resource not existing, or the + throws an exception when asked for it. This could occur for a variety +of reasons, such as the corresponding resource not existing, or the resource existing but ParseModule - throwing an exception when trying to parse the resulting source text. -Hosts can choose to expose the cause of failure via the exception they + throwing an exception when trying to parse the resulting source text. +Hosts can choose to expose the cause of failure via the exception they throw from HostResolveImportedModule. In any case, this exception causes an instantiation failure, which as before results in A's [[Status]] remaining "uninstantiated".

    Lastly, consider a module graph with a cycle:

    @@ -21711,9 +21711,9 @@ throw from InnerModuleInstantiation on A. However, once we unwind back to the original InnerModuleInstantiation on A, it fails during InitializeEnvironment, namely right after C.ResolveExport(). The thrown SyntaxError exception propagates up to A.Instantiate, which resets all modules that are currently on its stack (these are always exactly the modules that are still "instantiating"). Hence both A and B become "uninstantiated". Note that C is left as "instantiated".

    -

    Finally, consider a case where A has an -evaluation error; for example, its source code throws an exception. In -that case, the evaluation-time analog of the above steps still occurs, +

    Finally, consider a case where A has an +evaluation error; for example, its source code throws an exception. In +that case, the evaluation-time analog of the above steps still occurs, including the early return from the second call to InnerModuleEvaluation on A. However, once we unwind back to the original InnerModuleEvaluation on A, it fails by assumption. The exception thrown propagates up to A.Evaluate(), which records the error in all modules that are currently on its stack (i.e., the modules that are still "evaluating"). Hence both A and B become "evaluated" and the exception is recorded in both A and B's [[EvaluationError]] fields, while C is left as "evaluated" with no [[EvaluationError]].

    @@ -21722,7 +21722,7 @@ including the early return from the second call to 15.2.1.17Source Text Module Records

    A Source Text Module Record is used to represent information about a module that was defined from ECMAScript source text (10) that was parsed using the goal symbol Module. - Its fields contain digested information about the names that are + Its fields contain digested information about the names that are imported by the module and its concrete methods use this digest to link, instantiate, and evaluate the module.

    @@ -21735,87 +21735,87 @@ imported by the module and its concrete methods use this digest to link, Field Name - + Value Type - + Meaning - + [[ECMAScriptCode]] - + a Parse Node - + The result of parsing the source text of this module using Module as the goal symbol. - + [[ImportEntries]] - + List of ImportEntry Records - + A List of ImportEntry records derived from the code of this module. - + [[LocalExportEntries]] - + List of ExportEntry Records - + A List of ExportEntry records derived from the code of this module that correspond to declarations that occur within the module. - + [[IndirectExportEntries]] - + List of ExportEntry Records - + A List of ExportEntry records derived from the code of this module that correspond to reexported imports that occur within the module. - + [[StarExportEntries]] - + List of ExportEntry Records - + A List - of ExportEntry records derived from the code of this module that + of ExportEntry records derived from the code of this module that correspond to export * declarations that occur within the module. - + @@ -21828,57 +21828,57 @@ correspond to export * declarations that occur within the module. Field Name - + Value Type - + Meaning - + [[ModuleRequest]] - + String - + String value of the ModuleSpecifier of the ImportDeclaration. - + [[ImportName]] - + String - + The name under which the desired binding is exported by the module identified by [[ModuleRequest]]. The value "*" indicates that the import request is for the target module's namespace object. - + [[LocalName]] - + String - + The name that is used to locally access the imported value from within the importing module. - + @@ -21892,101 +21892,101 @@ correspond to export * declarations that occur within the module. Import Statement Form - + [[ModuleRequest]] - + [[ImportName]] - + [[LocalName]] - + import v from "mod"; - + "mod" - + "default" - + "v" - + import * as ns from "mod"; - + "mod" - + "*" - + "ns" - + import {x} from "mod"; - + "mod" - + "x" - + "x" - + import {x as v} from "mod"; - + "mod" - + "x" - + "v" - + import "mod"; - + An ImportEntry Record is not created. - + @@ -22000,71 +22000,71 @@ correspond to export * declarations that occur within the module. Field Name - + Value Type - + Meaning - + [[ExportName]] - + String | null - + The name used to export this binding by this module. - + [[ModuleRequest]] - + String | null - + The String value of the ModuleSpecifier of the ExportDeclaration. null if the ExportDeclaration does not have a ModuleSpecifier. - + [[ImportName]] - + String | null - + The name under which the desired binding is exported by the module identified by [[ModuleRequest]]. null if the ExportDeclaration does not have a ModuleSpecifier. "*" indicates that the export request is for all exported bindings. - + [[LocalName]] - + String | null - + The name that is used to locally access the exported value from within the importing module. null if the exported value is not locally accessible from within the module. - + @@ -22078,221 +22078,221 @@ correspond to export * declarations that occur within the module. Export Statement Form - + [[ExportName]] - + [[ModuleRequest]] - + [[ImportName]] - + [[LocalName]] - + export var v; - + "v" - + null - + null - + "v" - + export default function f(){} - + "default" - + null - + null - + "f" - + export default function(){} - + "default" - + null - + null - + "*default*" - + export default 42; - + "default" - + null - + null - + "*default*" - + export {x}; - + "x" - + null - + null - + "x" - + export {v as x}; - + "x" - + null - + null - + "v" - + export {x} from "mod"; - + "x" - + "mod" - + "x" - + null - + export {v as x} from "mod"; - + "x" - + "mod" - + "v" - + null - + export * from "mod"; - + null - + "mod" - + "*" - + null - + @@ -22307,10 +22307,10 @@ correspond to export * declarations that occur within the module.
    1. Assert: sourceText is an ECMAScript source text (see clause 10).
    2. Parse sourceText using Module as the goal symbol and analyse the parse result for any Early Error conditions. If the parse was successful and no early errors were found, let body be the resulting parse tree. Otherwise, let body be a List of one or more SyntaxError or ReferenceError objects representing the parsing errors and/or early errors. Parsing and early error detection may be interweaved in an implementation-dependent manner. If more than one parsing error or early error is present, the number and ordering of error objects in the list is implementation-dependent, but at least one must be present.
    3. If body is a List of errors, return body.
    4. Let requestedModules be the ModuleRequests of body.
    5. Let importEntries be ImportEntries of body.
    6. Let importedBoundNames be ImportedLocalNames(importEntries).
    7. Let indirectExportEntries be a new empty List.
    8. Let localExportEntries be a new empty List.
    9. Let starExportEntries be a new empty List.
    10. Let exportEntries be ExportEntries of body.
    11. For each ExportEntry Record ee in exportEntries, do
      1. If ee.[[ModuleRequest]] is null, then
        1. If ee.[[LocalName]] is not an element of importedBoundNames, then
          1. Append ee to localExportEntries.
        2. Else,
          1. Let ie be the element of importEntries whose [[LocalName]] is the same as ee.[[LocalName]].
          2. If ie.[[ImportName]] is "*", then
            1. Assert: This is a re-export of an imported module namespace object.
            2. Append ee to localExportEntries.
          3. Else this is a re-export of a single name,
            1. Append the ExportEntry Record { [[ModuleRequest]]: ie.[[ModuleRequest]], [[ImportName]]: ie.[[ImportName]], [[LocalName]]: null, [[ExportName]]: ee.[[ExportName]] } to indirectExportEntries.
      2. Else if ee.[[ImportName]] is "*", then
        1. Append ee to starExportEntries.
      3. Else,
        1. Append ee to indirectExportEntries.
    12. Return Source Text Module Record { [[Realm]]: realm, [[Environment]]: undefined, [[Namespace]]: undefined, [[Status]]: "uninstantiated", [[EvaluationError]]: undefined, [[HostDefined]]: hostDefined, [[ECMAScriptCode]]: body, [[RequestedModules]]: requestedModules, [[ImportEntries]]: importEntries, [[LocalExportEntries]]: localExportEntries, [[IndirectExportEntries]]: indirectExportEntries, [[StarExportEntries]]: starExportEntries, [[DFSIndex]]: undefined, [[DFSAncestorIndex]]: undefined }.
    Note
    -

    An implementation may parse module source text and -analyse it for Early Error conditions prior to the evaluation of -ParseModule for that module source text. However, the reporting of any -errors must be deferred until the point where this specification +

    An implementation may parse module source text and +analyse it for Early Error conditions prior to the evaluation of +ParseModule for that module source text. However, the reporting of any +errors must be deferred until the point where this specification actually performs ParseModule upon that source text.

     @@ -22330,13 +22330,13 @@ actually performs ParseModule upon that source text.

    15.2.1.17.3ResolveExport ( exportName, resolveSet ) Concrete Method

    The ResolveExport concrete method of a Source Text Module Record implements the corresponding Module Record abstract method.

    -

    ResolveExport attempts to resolve an imported binding to -the actual defining module and local binding name. The defining module +

    ResolveExport attempts to resolve an imported binding to +the actual defining module and local binding name. The defining module may be the module represented by the Module Record this method was invoked on or some other module that is imported by that module. The parameter resolveSet is used to detect unresolved circular import/export paths. If a pair consisting of specific Module Record and exportName is reached that is already in resolveSet, an import circularity has been encountered. Before recursively calling ResolveExport, a pair consisting of module and exportName is added to resolveSet.

    If a defining module is found, a ResolvedBinding Record { [[Module]], [[BindingName]] } is returned. This record identifies the - resolved binding of the originally requested export. If no definition + resolved binding of the originally requested export. If no definition was found or the request is found to be circular, null is returned. If the request is found to be ambiguous, the string "ambiguous" is returned.

    This abstract method performs the following steps:

    @@ -22375,20 +22375,20 @@ was found or the request is found to be circular, null is ret
    • The normal return value must be an instance of a concrete subclass of Module Record. - +
    • If a Module Record corresponding to the pair referencingModule, specifier does not exist or cannot be created, an exception must be thrown. - +
    • This operation must be idempotent if it completes normally. Each time it is called with a specific referencingModule, specifier pair as arguments it must return the same Module Record instance. - +

    Multiple different referencingModule, specifier pairs may map to the same Module Record instance. The actual mapping semantic is implementation-defined but typically a normalization process is applied to specifier - as part of the mapping process. A typical normalization process would -include actions such as alphabetic case folding and expansion of + as part of the mapping process. A typical normalization process would +include actions such as alphabetic case folding and expansion of relative and abbreviated path specifiers.

    @@ -22403,9 +22403,9 @@ relative and abbreviated path specifiers.

    Note

    The only way GetModuleNamespace can throw is via one of the triggered HostResolveImportedModule - calls. Unresolvable names are simply excluded from the namespace at -this point. They will lead to a real instantiation error later unless -they are all ambiguous star exports that are not explicitly requested + calls. Unresolvable names are simply excluded from the namespace at +this point. They will lead to a real instantiation error later unless +they are all ambiguous star exports that are not explicitly requested anywhere.

     @@ -22417,7 +22417,7 @@ anywhere.

    Note

    An implementation may parse a sourceText as a Module, analyse it for Early Error conditions, and instantiate it prior to the execution of the TopLevelModuleEvaluationJob for that sourceText. An implementation may also resolve, pre-parse and pre-analyse, and pre-instantiate module dependencies of sourceText. - However, the reporting of any errors detected by these actions must be + However, the reporting of any errors detected by these actions must be deferred until the TopLevelModuleEvaluationJob is actually executed.

     @@ -22501,7 +22501,7 @@ deferred until the TopLevelModuleEvaluationJob is actually executed.

    • It is a Syntax Error if the BoundNames of ImportDeclaration contains any duplicate entries. - +
    @@ -22659,7 +22659,7 @@ deferred until the TopLevelModuleEvaluationJob is actually executed.

    • For each IdentifierName n in ReferencedBindings of ExportClause: It is a Syntax Error if StringValue of n is a ReservedWord or if the StringValue of n is one of: "implements", "interface", "let", "package", "private", "protected", "public", or "static". - +
    Note
    @@ -22906,8 +22906,8 @@ deferred until the TopLevelModuleEvaluationJob is actually executed.

    Note

    It is not necessary to treat export default AssignmentExpression - as a constant declaration because there is no syntax that permits -assignment to the internal bound name used to reference a module's + as a constant declaration because there is no syntax that permits +assignment to the internal bound name used to reference a module's default object.

     @@ -23035,37 +23035,37 @@ default object.

    16Error Handling and Language Extensions

    An implementation must report most errors at the time the relevant ECMAScript language construct is evaluated. An early error is an error that can be detected and reported prior to the evaluation of any construct in the Script containing the error. The presence of an early error prevents the evaluation of the construct. An implementation must report early errors in a Script as part of parsing that Script in ParseScript. Early errors in a Module are reported at the point when the Module would be evaluated and the Module is never initialized. Early errors in eval code are reported at the time eval is called and prevent evaluation of the eval code. All errors that are not early errors are runtime errors.

    An implementation must report as an early error any occurrence of a condition that is listed in a “Static Semantics: Early Errors” subclause of this specification.

    -

    An implementation shall not treat other kinds of errors as early -errors even if the compiler can prove that a construct cannot execute -without error under any circumstances. An implementation may issue an -early warning in such a case, but it should not report the error until +

    An implementation shall not treat other kinds of errors as early +errors even if the compiler can prove that a construct cannot execute +without error under any circumstances. An implementation may issue an +early warning in such a case, but it should not report the error until the relevant construct is actually executed.

    An implementation shall report all errors as specified, except for the following:

    • Except as restricted in 16.2, an implementation may extend Script syntax, Module syntax, and regular expression pattern or flag syntax. To permit this, all operations (such as calling eval, using a regular expression literal, or using the Function or RegExp constructor) that are allowed to throw SyntaxError are permitted to exhibit implementation-defined behaviour instead of throwing SyntaxError when they encounter an implementation-defined extension to the script syntax or regular expression pattern or flag syntax. - +
    • Except as restricted in 16.2, - an implementation may provide additional types, values, objects, -properties, and functions beyond those described in this specification. -This may cause constructs (such as looking up a variable in the global -scope) to have implementation-defined behaviour instead of throwing an + an implementation may provide additional types, values, objects, +properties, and functions beyond those described in this specification. +This may cause constructs (such as looking up a variable in the global +scope) to have implementation-defined behaviour instead of throwing an error (such as ReferenceError). - +

    16.1HostReportErrors ( errorList )

    -

    HostReportErrors is an implementation-defined abstract operation -that allows host environments to report parsing errors, early errors, +

    HostReportErrors is an implementation-defined abstract operation +that allows host environments to report parsing errors, early errors, and runtime errors.

    -

    An implementation of HostReportErrors must complete normally in -all cases. The default implementation of HostReportErrors is to +

    An implementation of HostReportErrors must complete normally in +all cases. The default implementation of HostReportErrors is to unconditionally return an empty normal completion.

    Note
    @@ -23079,43 +23079,43 @@ unconditionally return an empty normal completion.

    @@ -23125,50 +23125,50 @@ unconditionally return an empty normal completion.

    17ECMAScript Standard Built-in Objects

    There are certain built-in objects available whenever an ECMAScript Script or Module begins execution. One, the global object, is part of the lexical environment of the executing program. Others are accessible as initial properties of the global object or indirectly as properties of accessible built-in objects.

    Unless specified otherwise, a built-in object that is callable as a function is a built-in function object with the characteristics described in 9.3. Unless specified otherwise, the [[Extensible]] internal slot of a built-in object initially has the value true. Every built-in function object has a [[Realm]] internal slot whose value is the Realm Record of the realm for which the object was initially created.

    -

    Many built-in objects are functions: they can be invoked with +

    Many built-in objects are functions: they can be invoked with arguments. Some of them furthermore are constructors: they are functions - intended for use with the new operator. For each built-in -function, this specification describes the arguments required by that + intended for use with the new operator. For each built-in +function, this specification describes the arguments required by that function and the properties of that function object. For each built-in constructor, this specification furthermore describes properties of the prototype object of that constructor and properties of specific object instances returned by a new expression that invokes that constructor.

    Unless otherwise specified in the description of a particular function, if a built-in function or constructor is given fewer arguments than the function is specified to require, the function or constructor shall behave exactly as if it had been given sufficient additional arguments, each such argument being the undefined - value. Such missing arguments are considered to be “not present” and -may be identified in that manner by specification algorithms. In the + value. Such missing arguments are considered to be “not present” and +may be identified in that manner by specification algorithms. In the description of a particular function, the terms “this value” and “NewTarget” have the meanings given in 9.3.

    Unless otherwise specified in the description of a particular function, if a built-in function or constructor - described is given more arguments than the function is specified to + described is given more arguments than the function is specified to allow, the extra arguments are evaluated by the call and then ignored by - the function. However, an implementation may define implementation -specific behaviour relating to such arguments as long as the behaviour + the function. However, an implementation may define implementation +specific behaviour relating to such arguments as long as the behaviour is not the throwing of a TypeError exception that is predicated simply on the presence of an extra argument.

    Note 1
    -

    Implementations that add additional capabilities to the set of -built-in functions are encouraged to do so by adding new functions +

    Implementations that add additional capabilities to the set of +built-in functions are encouraged to do so by adding new functions rather than adding new parameters to existing functions.

    Unless otherwise specified every built-in function and every built-in constructor has the Function prototype object, which is the initial value of the expression Function.prototype (19.2.3), as the value of its [[Prototype]] internal slot.

    -

    Unless otherwise specified every built-in prototype object has the +

    Unless otherwise specified every built-in prototype object has the Object prototype object, which is the initial value of the expression Object.prototype (19.1.3), as the value of its [[Prototype]] internal slot, except the Object prototype object itself.

    -

    Built-in function objects that are not identified as constructors -do not implement the [[Construct]] internal method unless otherwise +

    Built-in function objects that are not identified as constructors +do not implement the [[Construct]] internal method unless otherwise specified in the description of a particular function.

    Each built-in function defined in this specification is created by calling the CreateBuiltinFunction abstract operation (9.3.3).

    Every built-in function object, including constructors, has a "length" - property whose value is an integer. Unless otherwise specified, this -value is equal to the largest number of named arguments shown in the -subclause headings for the function description. Optional parameters + property whose value is an integer. Unless otherwise specified, this +value is equal to the largest number of named arguments shown in the +subclause headings for the function description. Optional parameters (which are indicated with brackets: [ ]) or rest parameters (which are shown using the form «...name») are not included in the default argument count.

    Note 2

    For example, the function object that is the initial value of the map property of the Array prototype object is described under the subclause heading «Array.prototype.map (callbackFn [ , thisArg])» which shows the - two named arguments callbackFn and thisArg, the latter being optional; + two named arguments callbackFn and thisArg, the latter being optional; therefore the value of the "length" property of that function object is 1.

    Unless otherwise specified, the "length" property of a built-in function object has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.

    Every built-in function object, including constructors, that is not identified as an anonymous function has a name - property whose value is a String. Unless otherwise specified, this -value is the name that is given to the function in this specification. -For functions that are specified as properties of objects, the name + property whose value is a String. Unless otherwise specified, this +value is the name that is given to the function in this specification. +For functions that are specified as properties of objects, the name value is the property name string used to access the function. Functions that are specified as get or set accessor functions of built-in properties have "get " or "set " prepended to the property name string. The value of the name property is explicitly specified for each built-in functions whose property key is a Symbol value.

    Unless otherwise specified, the name property of a built-in function object, if it exists, has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.

    Every other data property described in clauses 18 through 26 and in Annex B.2 has the attributes { [[Writable]]: true, [[Enumerable]]: false, [[Configurable]]: true } unless otherwise specified.

    @@ -23183,8 +23183,8 @@ value is the constructor with the new operator.
  • does not have a [[Call]] internal method; it cannot be invoked as a function.
  • has a [[Prototype]] internal slot whose value is implementation-dependent.
    • -
  • may have host defined properties in addition to the properties -defined in this specification. This may include a property whose value +
  • may have host defined properties in addition to the properties +defined in this specification. This may include a property whose value is the global object itself.
    • @@ -23222,12 +23222,12 @@ is the global object itself.
    1. Assert: If direct is false, then strictCaller is also false.
    2. If Type(x) is not String, return x.
    3. Let thisEnvRec be ! GetThisEnvironment().
    4. If thisEnvRec is a function Environment Record, then
      1. Let F be thisEnvRec.[[FunctionObject]].
      2. Let inFunction be true.
      3. Let inMethod be thisEnvRec.HasSuperBinding().
      4. If F.[[ConstructorKind]] is "derived", let inDerivedConstructor be true; otherwise, let inDerivedConstructor be false.
    5. Else,
      1. Let inFunction be false.
      2. Let inMethod be false.
      3. Let inDerivedConstructor be false.
    6. Let script be the ECMAScript code that is the result of parsing x, interpreted as UTF-16 encoded Unicode text as described in 6.1.4, for the goal symbol Script. If inFunction is false, additional early error rules from 18.2.1.1.1 are applied. If inMethod is false, additional early error rules from 18.2.1.1.2 are applied. If inDerivedConstructor is false, additional early error rules from 18.2.1.1.3 are applied. If the parse fails, throw a SyntaxError exception. If any early errors are detected, throw a SyntaxError or a ReferenceError exception, depending on the type of the error (but see also clause 16). Parsing and early error detection may be interweaved in an implementation-dependent manner.
    7. If script Contains ScriptBody is false, return undefined.
    8. Let body be the ScriptBody of script.
    9. If strictCaller is true, let strictEval be true.
    10. Else, let strictEval be IsStrict of script.
    11. Let ctx be the running execution context.
    12. NOTE: If direct is true, ctx will be the execution context that performed the direct eval. If direct is false, ctx will be the execution context for the invocation of the eval function.
    13. If direct is true, then
      1. Let lexEnv be NewDeclarativeEnvironment(ctx's LexicalEnvironment).
      2. Let varEnv be ctx's VariableEnvironment.
    14. Else,
      1. Let lexEnv be NewDeclarativeEnvironment(evalRealm.[[GlobalEnv]]).
      2. Let varEnv be evalRealm.[[GlobalEnv]].
    15. If strictEval is true, set varEnv to lexEnv.
    16. If ctx is not already suspended, suspend ctx.
    17. Let evalCxt be a new ECMAScript code execution context.
    18. Set the evalCxt's Function to null.
    19. Set the evalCxt's Realm to evalRealm.
    20. Set the evalCxt's ScriptOrModule to ctx's ScriptOrModule.
    21. Set the evalCxt's VariableEnvironment to varEnv.
    22. Set the evalCxt's LexicalEnvironment to lexEnv.
    23. Push evalCxt on to the execution context stack; evalCxt is now the running execution context.
    24. Let result be EvalDeclarationInstantiation(body, varEnv, lexEnv, strictEval).
    25. If result.[[Type]] is normal, then
      1. Set result to the result of evaluating body.
    26. If result.[[Type]] is normal and result.[[Value]] is empty, then
      1. Set result to NormalCompletion(undefined).
    27. Suspend evalCxt and remove it from the execution context stack.
    28. Resume the context that is now on the top of the execution context stack as the running execution context.
    29. Return Completion(result).
    Note
    -

    The eval code cannot instantiate variable or function +

    The eval code cannot instantiate variable or function bindings in the variable environment of the calling context that invoked - the eval if the calling context is evaluating formal parameter -initializers or if either the code of the calling context or the eval + the eval if the calling context is evaluating formal parameter +initializers or if either the code of the calling context or the eval code is strict mode code. - Instead such bindings are instantiated in a new VariableEnvironment + Instead such bindings are instantiated in a new VariableEnvironment that is only accessible to the eval code. Bindings introduced by let, const, or class declarations are always instantiated in a new LexicalEnvironment.

     @@ -23268,13 +23268,13 @@ that is only accessible to the eval code. Bindings introduced by let

    18.2.1.2HostEnsureCanCompileStrings ( callerRealm, calleeRealm )

    -

    HostEnsureCanCompileStrings is an implementation-defined -abstract operation that allows host environments to block certain -ECMAScript functions which allow developers to compile strings into +

    HostEnsureCanCompileStrings is an implementation-defined +abstract operation that allows host environments to block certain +ECMAScript functions which allow developers to compile strings into ECMAScript code.

    An implementation of HostEnsureCanCompileStrings may complete - normally or abruptly. Any abrupt completions will be propagated to its + normally or abruptly. Any abrupt completions will be propagated to its callers. The default implementation of HostEnsureCanCompileStrings is to unconditionally return an empty normal completion.

    @@ -23289,8 +23289,8 @@ callers. The default implementation of HostEnsureCanCompileStrings is to #sec-variablestatements-in-catch-blocks accordingly. -->
    1. Let varNames be the VarDeclaredNames of body.
    2. Let varDeclarations be the VarScopedDeclarations of body.
    3. Let lexEnvRec be lexEnv's EnvironmentRecord.
    4. Let varEnvRec be varEnv's EnvironmentRecord.
    5. If strict is false, then
      1. If varEnvRec is a global Environment Record, then
        1. For each name in varNames, do
          1. If varEnvRec.HasLexicalDeclaration(name) is true, throw a SyntaxError exception.
          2. NOTE: eval will not create a global var declaration that would be shadowed by a global lexical declaration.
      2. Let thisLex be lexEnv.
      3. Assert: The following loop will terminate.
      4. Repeat, while thisLex is not the same as varEnv,
        1. Let thisEnvRec be thisLex's EnvironmentRecord.
        2. If thisEnvRec is not an object Environment Record, then
          1. NOTE: - The environment of with statements cannot contain any lexical -declaration so it doesn't need to be checked for var/let hoisting + The environment of with statements cannot contain any lexical +declaration so it doesn't need to be checked for var/let hoisting conflicts.
          2. For each name in varNames, do
            1. If thisEnvRec.HasBinding(name) is true, then
              1. Throw a SyntaxError exception.
              2. NOTE: Annex B.3.5 defines alternate semantics for the above step.
            2. NOTE: A direct eval will not hoist var declaration over a like-named lexical declaration.
        3. Set thisLex to thisLex's outer environment reference.
    6. Let functionsToInitialize be a new empty List.
    7. Let declaredFunctionNames be a new empty List.
    8. For each d in varDeclarations, in reverse list order, do
      1. If d is neither a VariableDeclaration nor a ForBinding nor a BindingIdentifier, then
        1. Assert: d is either a FunctionDeclaration, a GeneratorDeclaration, an AsyncFunctionDeclaration, or an AsyncGeneratorDeclaration.
        2. NOTE: If there are multiple function declarations for the same name, the last declaration is used.
        3. Let fn be the sole element of the BoundNames of d.
        4. If fn is not an element of declaredFunctionNames, then
          1. If varEnvRec is a global Environment Record, then
            1. Let fnDefinable be ? varEnvRec.CanDeclareGlobalFunction(fn).
            2. If fnDefinable is false, throw a TypeError exception.
          2. Append fn to declaredFunctionNames.
          3. Insert d as the first element of functionsToInitialize.
    9. NOTE: Annex B.3.3.3 adds additional steps at this point.
    10. Let declaredVarNames be a new empty List.
    11. For each d in varDeclarations, do
      1. If d is a VariableDeclaration, a ForBinding, or a BindingIdentifier, then
        1. For each String vn in the BoundNames of d, do
          1. If vn is not an element of declaredFunctionNames, then
            1. If varEnvRec is a global Environment Record, then
              1. Let vnDefinable be ? varEnvRec.CanDeclareGlobalVar(vn).
              2. If vnDefinable is false, throw a TypeError exception.
            2. If vn is not an element of declaredVarNames, then
              1. Append vn to declaredVarNames.
    12. NOTE: No abnormal terminations occur after this algorithm step unless varEnvRec is a global Environment Record and the global object is a Proxy exotic object.
    13. Let lexDeclarations be the LexicallyScopedDeclarations of body.
    14. For each element d in lexDeclarations, do
      1. NOTE: Lexically declared names are only instantiated here but not initialized.
      2. For each element dn of the BoundNames of d, do
        1. If IsConstantDeclaration of d is true, then
          1. Perform ? lexEnvRec.CreateImmutableBinding(dn, true).
        2. Else,
          1. Perform ? lexEnvRec.CreateMutableBinding(dn, false).
    15. For each Parse Node f in functionsToInitialize, do
      1. Let fn be the sole element of the BoundNames of f.
      2. Let fo be the result of performing InstantiateFunctionObject for f with argument lexEnv.
      3. If varEnvRec is a global Environment Record, then
        1. Perform ? varEnvRec.CreateGlobalFunctionBinding(fn, fo, true).
      4. Else,
        1. Let bindingExists be varEnvRec.HasBinding(fn).
        2. If bindingExists is false, then
          1. Let status be ! varEnvRec.CreateMutableBinding(fn, true).
          2. Assert: status is not an abrupt completion because of validation preceding step 12.
          3. Perform ! varEnvRec.InitializeBinding(fn, fo).
        3. Else,
          1. Perform ! varEnvRec.SetMutableBinding(fn, fo, false).
    16. For each String vn in declaredVarNames, in list order, do
      1. If varEnvRec is a global Environment Record, then
        1. Perform ? varEnvRec.CreateGlobalVarBinding(vn, true).
      2. Else,
        1. Let bindingExists be varEnvRec.HasBinding(vn).
        2. If bindingExists is false, then
          1. Let status be ! varEnvRec.CreateMutableBinding(vn, true).
          2. Assert: status is not an abrupt completion because of validation preceding step 12.
          3. Perform ! varEnvRec.InitializeBinding(vn, undefined).
    17. Return NormalCompletion(empty).
    Note
    @@ -23325,7 +23325,7 @@ conflicts.
  • For each name in varNames, do
    1. If Note

      parseFloat may interpret only a leading portion of string as a Number value; it ignores any code units that cannot be interpreted - as part of the notation of a decimal literal, and no indication is + as part of the notation of a decimal literal, and no indication is given that any such code units were ignored.

       @@ -23336,27 +23336,27 @@ given that any such code units were ignored.

      The parseInt function is the %parseInt% intrinsic object. When the parseInt function is called, the following steps are taken:

      1. Let inputString be ? ToString(string).
      2. Let S be a newly created substring of inputString consisting of the first code unit that is not a StrWhiteSpaceChar and all code units following that code unit. (In other words, remove leading white space.) If inputString does not contain any such code unit, let S be the empty string.
      3. Let sign be 1.
      4. If S is not empty and the first code unit of S is the code unit 0x002D (HYPHEN-MINUS), set sign to -1.
      5. If S is not empty and the first code unit of S is the code unit 0x002B (PLUS SIGN) or the code unit 0x002D (HYPHEN-MINUS), remove the first code unit from S.
      6. Let R be ? ToInt32(radix).
      7. Let stripPrefix be true.
      8. If R ≠ 0, then
        1. If R < 2 or R > 36, return NaN.
        2. If R ≠ 16, set stripPrefix to false.
      9. Else R = 0,
        1. Set R to 10.
      10. If stripPrefix is true, then
        1. If the length of S is at least 2 and the first two code units of S are either "0x" or "0X", then
          1. Remove the first two code units from S.
          2. Set R to 16.
      11. If S contains a code unit that is not a radix-R digit, let Z be the substring of S consisting of all code units before the first such code unit; otherwise, let Z be S.
      12. If Z is empty, return NaN.
      13. Let mathInt be the mathematical integer value that is represented by Z in radix-R notation, using the letters A-Z and a-z for digits with values 10 through 35. (However, if R is 10 and Z contains more than 20 significant digits, every significant digit after - the 20th may be replaced by a 0 digit, at the option of the + the 20th may be replaced by a 0 digit, at the option of the implementation; and if R is not 2, 4, 8, 10, 16, or 32, then mathInt may be an implementation-dependent approximation to the mathematical integer value that is represented by Z in radix-R notation.)
      14. If mathInt = 0, then
        1. If sign = -1, return -0.
        2. Return +0.
      15. Let number be the Number value for mathInt.
      16. Return sign × number.
      Note

      parseInt may interpret only a leading portion of string - as an integer value; it ignores any code units that cannot be -interpreted as part of the notation of an integer, and no indication is + as an integer value; it ignores any code units that cannot be +interpreted as part of the notation of an integer, and no indication is given that any such code units were ignored.

      18.2.6URI Handling Functions

      -

      Uniform Resource Identifiers, or URIs, are Strings that -identify resources (e.g. web pages or files) and transport protocols by -which to access them (e.g. HTTP or FTP) on the Internet. The ECMAScript -language itself does not provide any support for using URIs except for +

      Uniform Resource Identifiers, or URIs, are Strings that +identify resources (e.g. web pages or files) and transport protocols by +which to access them (e.g. HTTP or FTP) on the Internet. The ECMAScript +language itself does not provide any support for using URIs except for functions that encode and decode URIs as described in 18.2.6.2, 18.2.6.3, 18.2.6.4 and 18.2.6.5

      Note
      -

      Many implementations of ECMAScript provide additional -functions and methods that manipulate web pages; these functions are +

      Many implementations of ECMAScript provide additional +functions and methods that manipulate web pages; these functions are beyond the scope of this standard.

       @@ -23365,15 +23365,15 @@ beyond the scope of this standard.

      A URI is composed of a sequence of components separated by component separators. The general form is:

      Scheme : First / Second ; Third ? Fourth - +

      where the italicized names represent components and “:”, “/”, “;” and “?” are reserved for use as separators. The encodeURI and decodeURI functions are intended to work with complete URIs; they assume that any reserved code units in the URI are intended to have special meaning and so are not encoded. The encodeURIComponent and decodeURIComponent functions are intended to work with the individual component parts of a - URI; they assume that any reserved code units represent text and so -must be encoded so that they are not interpreted as reserved code units + URI; they assume that any reserved code units represent text and so +must be encoded so that they are not interpreted as reserved code units when the component is part of a complete URI.

      The following lexical grammar specifies the form of encoded URIs.

      Syntax

      @@ -23409,14 +23409,14 @@ when the component is part of a complete URI.

      The above syntax is based upon RFC 2396 and does not reflect changes introduced by the more recent RFC 3986.

    •

    Runtime Semantics

    -

    When a code unit to be included in a URI is not listed above -or is not intended to have the special meaning sometimes given to the -reserved code units, that code unit must be encoded. The code unit is +

    When a code unit to be included in a URI is not listed above +or is not intended to have the special meaning sometimes given to the +reserved code units, that code unit must be encoded. The code unit is transformed into its UTF-8 encoding, with surrogate pairs - first converted from UTF-16 to the corresponding code point value. + first converted from UTF-16 to the corresponding code point value. (Note that for code units in the range [0, 127] this results in a single - octet with the same value.) The resulting sequence of octets is then -transformed into a String with each octet represented by an escape + octet with the same value.) The resulting sequence of octets is then +transformed into a String with each octet represented by an escape sequence of the form "%xx".

    @@ -23433,15 +23433,15 @@ sequence of the form "%xx".

    Note

    This syntax of Uniform Resource Identifiers is based upon - RFC 2396 and does not reflect the more recent RFC 3986 which replaces -RFC 2396. A formal description and implementation of UTF-8 is given in + RFC 2396 and does not reflect the more recent RFC 3986 which replaces +RFC 2396. A formal description and implementation of UTF-8 is given in RFC 3629.

    In UTF-8, characters are encoded using sequences of 1 to 6 - octets. The only octet of a sequence of one has the higher-order bit + octets. The only octet of a sequence of one has the higher-order bit set to 0, the remaining 7 bits being used to encode the character value. - In a sequence of n octets, n > 1, the initial octet has the n -higher-order bits set to 1, followed by a bit set to 0. The remaining -bits of that octet contain bits from the value of the character to be + In a sequence of n octets, n > 1, the initial octet has the n +higher-order bits set to 1, followed by a bit set to 0. The remaining +bits of that octet contain bits from the value of the character to be encoded. The following octets all have the higher-order bit set to 1 and the following bit set to 0, leaving 6 bits in each to contain bits from the character to be encoded. The possible UTF-8 encodings of ECMAScript @@ -23452,33 +23452,33 @@ encoded. The following octets all have the higher-order bit set to 1 and Code Unit Value - + Representation - + 1st Octet - + 2nd Octet - + 3rd Octet - + 4th Octet - + 0x0000 - 0x007F - + 00000000 0zzzzzzz @@ -23496,7 +23496,7 @@ encoded. The following octets all have the higher-order bit set to 1 and 0x0080 - 0x07FF - + 00000yyy yyzzzzzz @@ -23515,7 +23515,7 @@ encoded. The following octets all have the higher-order bit set to 1 and 0x0800 - 0xD7FF - + xxxxyyyy yyzzzzzz @@ -23535,19 +23535,19 @@ encoded. The following octets all have the higher-order bit set to 1 and 0xD800 - 0xDBFF - +
    followed by - +
    0xDC00 - 0xDFFF - + 110110vv vvwwwwxx
    followed by - +
    110111yy yyzzzzzz @@ -23567,17 +23567,17 @@ encoded. The following octets all have the higher-order bit set to 1 and 0xD800 - 0xDBFF - +
    not followed by - +
    0xDC00 - 0xDFFF - + causes URIError - + @@ -23591,11 +23591,11 @@ encoded. The following octets all have the higher-order bit set to 1 and 0xDC00 - 0xDFFF - + causes URIError - + @@ -23609,7 +23609,7 @@ encoded. The following octets all have the higher-order bit set to 1 and 0xE000 - 0xFFFF - + xxxxyyyy yyzzzzzz @@ -23630,19 +23630,19 @@ encoded. The following octets all have the higher-order bit set to 1 and

    Where - +
    uuuuu = vvvv + 1 - +
    to account for the addition of 0x10000 as in section 3.8 of the Unicode Standard (Surrogates).

    The above transformation combines each surrogate pair (for which code unit values in the inclusive range 0xD800 to 0xDFFF are reserved) into a UTF-32 representation and encodes the resulting 21-bit value into UTF-8. Decoding reconstructs the surrogate pair.

    -

    RFC 3629 prohibits the decoding of invalid UTF-8 octet -sequences. For example, the invalid sequence C0 80 must not decode into -the code unit 0x0000. Implementations of the Decode algorithm are +

    RFC 3629 prohibits the decoding of invalid UTF-8 octet +sequences. For example, the invalid sequence C0 80 must not decode into +the code unit 0x0000. Implementations of the Decode algorithm are required to throw a URIError when encountering such invalid sequences.

     @@ -23652,8 +23652,8 @@ required to throw a URIError when encountering such invalid s

    18.2.6.2decodeURI ( encodedURI )

    The decodeURI function computes a new version of a URI in which each escape sequence and UTF-8 encoding of the sort that - might be introduced by the encodeURI function is replaced -with the UTF-16 encoding of the code points that it represents. Escape + might be introduced by the encodeURI function is replaced +with the UTF-16 encoding of the code points that it represents. Escape sequences that could not have been introduced by encodeURI are not replaced.

    The decodeURI function is the %decodeURI% intrinsic object. When the decodeURI function is called with one argument encodedURI, the following steps are taken:

    1. Let uriString be ? ToString(encodedURI).
    2. Let reservedURISet be a String containing one instance of each code unit valid in uriReserved plus "#".
    3. Return ? Decode(uriString, reservedURISet). @@ -23665,7 +23665,7 @@ sequences that could not have been introduced by encodeURI are not

      18.2.6.3decodeURIComponent ( encodedURIComponent )

      -

      The decodeURIComponent function computes a new +

      The decodeURIComponent function computes a new version of a URI in which each escape sequence and UTF-8 encoding of the sort that might be introduced by the encodeURIComponent function is replaced with the UTF-16 encoding of the code points that it represents.

      The decodeURIComponent function is the %decodeURIComponent% intrinsic object. When the decodeURIComponent function is called with one argument encodedURIComponent, the following steps are taken:

      @@ -23676,8 +23676,8 @@ version of a URI in which each escape sequence and UTF-8 encoding of the

      18.2.6.4encodeURI ( uri )

      The encodeURI function computes a new version of a UTF-16 encoded (6.1.4) - URI in which each instance of certain code points is replaced by one, -two, three, or four escape sequences representing the UTF-8 encoding of + URI in which each instance of certain code points is replaced by one, +two, three, or four escape sequences representing the UTF-8 encoding of the code points.

      The encodeURI function is the %encodeURI% intrinsic object. When the encodeURI function is called with one argument uri, the following steps are taken:

      1. Let uriString be ? ToString(uri).
      2. Let unescapedURISet be a String containing one instance of each code unit valid in uriReserved and uriUnescaped plus "#".
      3. Return ? Encode(uriString, unescapedURISet). @@ -23690,8 +23690,8 @@ the code points.

        18.2.6.5encodeURIComponent ( uriComponent )

        The encodeURIComponent function computes a new version of a UTF-16 encoded (6.1.4) - URI in which each instance of certain code points is replaced by one, -two, three, or four escape sequences representing the UTF-8 encoding of + URI in which each instance of certain code points is replaced by one, +two, three, or four escape sequences representing the UTF-8 encoding of the code point.

        The encodeURIComponent function is the %encodeURIComponent% intrinsic object. When the encodeURIComponent function is called with one argument uriComponent, the following steps are taken:

        1. Let componentString be ? ToString(uriComponent).
        2. Let unescapedURIComponentSet be a String containing one instance of each code unit valid in uriUnescaped.
        3. Return ? Encode(componentString, unescapedURIComponentSet). @@ -23991,13 +23991,13 @@ the code point.

         Note
        The function created for adder is never directly accessible to ECMAScript code. - +

        19.1.2.7.1CreateDataPropertyOnObject Functions

        -

        A CreateDataPropertyOnObject function is an anonymous -built-in function. When a CreateDataPropertyOnObject function is called +

        A CreateDataPropertyOnObject function is an anonymous +built-in function. When a CreateDataPropertyOnObject function is called with arguments key and value, the following steps are taken:

        1. Let O be the this value.
        2. Assert: Type(O) is Object.
        3. Assert: O is an extensible ordinary object.
        4. Let propertyKey be ? ToPropertyKey(key).
        5. Perform ! CreateDataPropertyOrThrow(O, propertyKey, value).
        6. Return undefined.
        @@ -24136,8 +24136,8 @@ with arguments key and value, the following steps are take
        1. Let P be ? ToPropertyKey(V).
        2. Let O be ? ToObject(this value).
        3. Return ? HasOwnProperty(O, P).
        Note
        -

        The ordering of steps 1 and 2 is chosen to ensure that any -exception that would have been thrown by step 1 in previous editions of +

        The ordering of steps 1 and 2 is chosen to ensure that any +exception that would have been thrown by step 1 in previous editions of this specification will continue to be thrown even if the this value is undefined or null.

                 @@ -24161,8 +24161,8 @@ this specification will continue to be thrown even if the thisThis method does not consider objects in the prototype chain.

        Note 2
        -

        The ordering of steps 1 and 2 is chosen to ensure that any -exception that would have been thrown by step 1 in previous editions of +

        The ordering of steps 1 and 2 is chosen to ensure that any +exception that would have been thrown by step 1 in previous editions of this specification will continue to be thrown even if the this value is undefined or null.

                 @@ -24189,10 +24189,10 @@ this specification will continue to be thrown even if the thisThis function is the %ObjProto_toString% intrinsic object.

        Note

        Historically, this function was occasionally used to access - the String value of the [[Class]] internal slot that was used in -previous editions of this specification as a nominal type tag for + the String value of the [[Class]] internal slot that was used in +previous editions of this specification as a nominal type tag for various built-in objects. The above definition of toString preserves compatibility for legacy code that uses toString - as a test for those specific kinds of built-in objects. It does not + as a test for those specific kinds of built-in objects. It does not provide a reliable type testing mechanism for other kinds of built-in or program defined objects. In addition, programs can use @@toStringTag in ways that will invalidate the reliability of such legacy type tests.

        @@ -24225,8 +24225,8 @@ provide a reliable type testing mechanism for other kinds of built-in or
      4. is the initial value of the Function property of the global object.
      5. creates and initializes a new function object when called as a function rather than as a constructor. Thus the function call Function(…) is equivalent to the object creation expression new Function(…) with the same arguments.
      6. is designed to be subclassable. It may be used as the value of an extends clause of a class definition. Subclass constructors that intend to inherit the specified Function behaviour must include a super call to the Function constructor - to create and initialize a subclass instance with the internal slots -necessary for built-in function behaviour. All ECMAScript syntactic + to create and initialize a subclass instance with the internal slots +necessary for built-in function behaviour. All ECMAScript syntactic forms for defining function objects create instances of Function. There is no syntactic means to create instances of Function subclasses except for the built-in GeneratorFunction, AsyncFunction, and AsyncGeneratorFunction subclasses.
        7. @@ -24237,7 +24237,7 @@ forms for defining function objects create instances of Function. T
        1. Let C be the active function object.
        2. Let args be the argumentsList that was passed to this function by [[Call]] or [[Construct]].
        3. Return ? CreateDynamicFunction(C, NewTarget, "normal", args).
        Note
        -

        It is permissible but not necessary to have one argument +

        It is permissible but not necessary to have one argument for each formal parameter to be specified. For example, all three of the following expressions produce the same result:

        new Function("a", "b", "c", "return a+b+c")
@@ -24253,8 +24253,8 @@ for each formal parameter to be specified. For example, all three of the
  are applied. Parsing and early error detection may be interweaved in an implementation-dependent manner.
      7. If strict is true and IsSimpleParameterList of parameters is false, throw a SyntaxError exception.
      8. If any element of the BoundNames of parameters also occurs in the LexicallyDeclaredNames of body, throw a SyntaxError exception.
      9. If body Contains SuperCall is true, throw a SyntaxError exception.
      10. If parameters Contains SuperCall is true, throw a SyntaxError exception.
      11. If body Contains SuperProperty is true, throw a SyntaxError exception.
      12. If parameters Contains SuperProperty is true, throw a SyntaxError exception.
      13. If kind is "generator" or "async generator", then
        1. If parameters Contains YieldExpression is true, throw a SyntaxError exception.
      14. If kind is "async" or "async generator", then
        1. If parameters Contains AwaitExpression is true, throw a SyntaxError exception.
      15. If strict is true, then
        1. If BoundNames of parameters contains any duplicate elements, throw a SyntaxError exception.
      16. Let proto be ? GetPrototypeFromConstructor(newTarget, fallbackProto).
      17. Let F be FunctionAllocate(proto, strict, kind).
      18. Let realmF be F.[[Realm]].
      19. Let scope be realmF.[[GlobalEnv]].
      20. Perform FunctionInitialize(F, Normal, parameters, body, scope).
      21. If kind is "generator", then
        1. Let prototype be ObjectCreate(%GeneratorPrototype%).
        2. Perform DefinePropertyOrThrow(F, "prototype", PropertyDescriptor { [[Value]]: prototype, [[Writable]]: true, [[Enumerable]]: false, [[Configurable]]: false }).
      22. Else if kind is "async generator", then
        1. Let prototype be ObjectCreate(%AsyncGeneratorPrototype%).
        2. Perform DefinePropertyOrThrow(F, "prototype", PropertyDescriptor { [[Value]]: prototype, [[Writable]]: true, [[Enumerable]]: false, [[Configurable]]: false }).
      23. Else if kind is "normal", perform MakeConstructor(F).
      24. NOTE: Async functions are not constructable and do not have a [[Construct]] internal method or a "prototype" property.
      25. Perform SetFunctionName(F, "anonymous").
      26. Let prefix be the prefix associated with kind in Table 47.
      27. Let sourceText be the string-concatenation of prefix, " anonymous(", P, 0x000A (LINE FEED), ") {", 0x000A (LINE FEED), bodyText, 0x000A (LINE FEED), and "}".
      28. Set F.[[SourceText]] to sourceText.
      29. Return F.
      Note
      -

      A prototype property is created for every -non-async function created using CreateDynamicFunction to provide for +

      A prototype property is created for every +non-async function created using CreateDynamicFunction to provide for the possibility that the function will be used as a constructor.

       @@ -24341,8 +24341,8 @@ the possibility that the function will be used as a 19.2.3.3Function.prototype.call ( thisArg, ...args )

      When the call method is called with argument thisArg and zero or more args, the following steps are taken:

      1. Let func be the this value.
      2. If IsCallable(func) is false, throw a TypeError exception.
      3. Let argList be a new empty List.
      4. If - this method was called with more than one argument, then in left to -right order, starting with the second argument, append each argument as + this method was called with more than one argument, then in left to +right order, starting with the second argument, append each argument as the last element of argList.
      5. Perform PrepareForTailCall().
      6. Return ? Call(func, thisArg, argList).
      Note 1
      @@ -24397,8 +24397,8 @@ the last element of argList.
    4. Perform

      19.2.4.1length

      The value of the "length" property is an integer - that indicates the typical number of arguments expected by the -function. However, the language permits the function to be invoked with + that indicates the typical number of arguments expected by the +function. However, the language permits the function to be invoked with some other number of arguments. The behaviour of a function when invoked on a number of arguments other than the number specified by its "length" property depends on the function. This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.

      @@ -24406,7 +24406,7 @@ some other number of arguments. The behaviour of a function when invoked

      19.2.4.2name

      The value of the name property is a String that is descriptive of the function. The name has no semantic significance but is typically a variable or property name - that is used to refer to the function at its point of definition in + that is used to refer to the function at its point of definition in ECMAScript code. This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.

      Anonymous functions objects that do not have a contextual name associated with them by this specification do not have a name own property but inherit the name property of %FunctionPrototype%.

       @@ -24425,14 +24425,14 @@ ECMAScript code. This property has the attributes { [[Writable]]: false

      19.2.5HostHasSourceTextAvailable ( func )

      -

      HostHasSourceTextAvailable is an implementation-defined -abstract operation that allows host environments to prevent the source +

      HostHasSourceTextAvailable is an implementation-defined +abstract operation that allows host environments to prevent the source text from being provided for a given function.

      -

      An implementation of HostHasSourceTextAvailable must complete +

      An implementation of HostHasSourceTextAvailable must complete normally in all cases. This operation must be deterministic with respect to its parameters. Each time it is called with a specific func as its argument, it must return the same completion record. The default - implementation of HostHasSourceTextAvailable is to unconditionally + implementation of HostHasSourceTextAvailable is to unconditionally return a normal completion with a value of true.

       @@ -24510,9 +24510,9 @@ return a normal completion with a value of true.

      19.3.4Properties of Boolean Instances

      -

      Boolean instances are ordinary objects that inherit properties -from the Boolean prototype object. Boolean instances have a -[[BooleanData]] internal slot. The [[BooleanData]] internal slot is the +

      Boolean instances are ordinary objects that inherit properties +from the Boolean prototype object. Boolean instances have a +[[BooleanData]] internal slot. The [[BooleanData]] internal slot is the Boolean value represented by this Boolean object.

       @@ -24560,7 +24560,7 @@ Boolean value represented by this Boolean object.

      1. Let stringKey be ? ToString(key).
      2. For each element e of the GlobalSymbolRegistry List, do
        1. If SameValue(e.[[Key]], stringKey) is true, return e.[[Symbol]].
      3. Assert: GlobalSymbolRegistry does not currently contain an entry for stringKey.
      4. Let newSymbol be a new unique Symbol value whose [[Description]] value is stringKey.
      5. Append the Record { [[Key]]: stringKey, [[Symbol]]: newSymbol } to the GlobalSymbolRegistry List.
      6. Return newSymbol.

      The GlobalSymbolRegistry is a List - that is globally available. It is shared by all realms. Prior to the + that is globally available. It is shared by all realms. Prior to the evaluation of any ECMAScript code it is initialized as a new empty List. Elements of the GlobalSymbolRegistry are Records with the structure defined in Table 48.

      Table 48: GlobalSymbolRegistry Record Fields
      @@ -24568,43 +24568,43 @@ evaluation of any ECMAScript code it is initialized as a new empty @@ -24741,7 +24741,7 @@ evaluation of any ECMAScript code it is initialized as a new empty

      19.4.3.5Symbol.prototype [ @@toPrimitive ] ( hint )

      -

      This function is called by ECMAScript language operators to +

      This function is called by ECMAScript language operators to convert a Symbol object to a primitive value. The allowed values for hint are "default", "number", and "string".

      When the @@toPrimitive method is called with argument hint, the following steps are taken:

      1. Return ? thisSymbolValue(this value). @@ -24759,17 +24759,17 @@ convert a Symbol object to a primitive value. The allowed values for hint

        19.4.4Properties of Symbol Instances

        -

        Symbol instances are ordinary objects that inherit properties +

        Symbol instances are ordinary objects that inherit properties from the Symbol prototype object. Symbol instances have a [[SymbolData]] - internal slot. The [[SymbolData]] internal slot is the Symbol value + internal slot. The [[SymbolData]] internal slot is the Symbol value represented by this Symbol object.

        19.5Error Objects

        -

        Instances of Error objects are thrown as exceptions when runtime -errors occur. The Error objects may also serve as base objects for +

        Instances of Error objects are thrown as exceptions when runtime +errors occur. The Error objects may also serve as base objects for user-defined exception classes.

        @@ -24840,8 +24840,8 @@ user-defined exception classes.

        19.5.4Properties of Error Instances

        -

        Error instances are ordinary objects that inherit properties -from the Error prototype object and have an [[ErrorData]] internal slot +

        Error instances are ordinary objects that inherit properties +from the Error prototype object and have an [[ErrorData]] internal slot whose value is undefined. The only specified uses of [[ErrorData]] is to identify Error and NativeError instances as Error objects within Object.prototype.toString.

         @@ -24851,8 +24851,8 @@ whose value is undefined. The only specified uses of [[ErrorD

        19.5.5.1EvalError

        -

        This exception is not currently used within this -specification. This object remains for compatibility with previous +

        This exception is not currently used within this +specification. This object remains for compatibility with previous editions of this specification.

         @@ -24988,8 +24988,8 @@ editions of this specification.

        20.1.2.1Number.EPSILON

        -

        The value of Number.EPSILON is the difference between 1 and -the smallest value greater than 1 that is representable as a Number +

        The value of Number.EPSILON is the difference between 1 and +the smallest value greater than 1 that is representable as a Number value, which is approximately 2.2204460492503130808472633361816 x 10 - 16.

        This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }.

         @@ -25052,8 +25052,8 @@ value, which is approximately 2.2204460492503130808472633361816 x 10 - 16

        20.1.2.9Number.MIN_VALUE

        The value of Number.MIN_VALUE is the smallest positive value of the Number type, which is approximately 5 × 10-324.

        -

        In the IEEE 754-2008 double precision binary representation, -the smallest possible value is a denormalized number. If an +

        In the IEEE 754-2008 double precision binary representation, +the smallest possible value is a denormalized number. If an implementation does not support denormalized values, the value of Number.MIN_VALUE must be the smallest non-zero positive value that can actually be represented by the implementation.

        This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: false }.

         @@ -25103,13 +25103,13 @@ implementation does not support denormalized values, the value of Number.M
      2. has a [[Prototype]] internal slot whose value is the intrinsic object %ObjectPrototype%.

        3. Unless explicitly stated otherwise, the methods of the Number prototype object defined below are not generic and the this - value passed to them must be either a Number value or an object that + value passed to them must be either a Number value or an object that has a [[NumberData]] internal slot that has been initialized to a Number value.

        The abstract operation thisNumberValue(value) performs the following steps:

        1. If Type(value) is Number, return value.
        2. If Type(value) is Object and value has a [[NumberData]] internal slot, then
          1. Let n be value.[[NumberData]].
          2. Assert: Type(n) is Number.
          3. Return n.
        3. Throw a TypeError exception.
        -

        The phrase “this Number value” within the specification of a +

        The phrase “this Number value” within the specification of a method refers to the result returned by calling the abstract operation thisNumberValue with the this value of the method invocation passed as the argument.

        @@ -25119,14 +25119,14 @@ method refers to the result returned by calling the abstract operation

        20.1.3.2Number.prototype.toExponential ( fractionDigits )

        -

        Return a String containing this Number value represented in -decimal exponential notation with one digit before the significand's +

        Return a String containing this Number value represented in +decimal exponential notation with one digit before the significand's decimal point and fractionDigits digits after the significand's decimal point. If fractionDigits is undefined, include as many significand digits as necessary to uniquely specify the Number (just like in ToString except that in this case the Number is always output in exponential notation). Specifically, perform the following steps:

        1. Let x be ? thisNumberValue(this value).
        2. Let f be ? ToInteger(fractionDigits).
        3. Assert: If fractionDigits is undefined, then f is 0.
        4. If x is NaN, return the String "NaN".
        5. Let s be the empty String.
        6. If x < 0, then
          1. Set s to "-".
          2. Set x to -x.
        7. If x = +∞, then
          1. Return the string-concatenation of s and "Infinity".
        8. If f < 0 or f > 100, throw a RangeError exception.
        9. If x = 0, then
          1. Let m be the String value consisting of f + 1 occurrences of the code unit 0x0030 (DIGIT ZERO).
          2. Let e be 0.
        10. Else x ≠ 0,
          1. If fractionDigits is not undefined, then
            1. Let e and n be integers such that 10f ≤ n < 10f + 1 and for which the exact mathematical value of n × 10e - f - x is as close to zero as possible. If there are two such sets of e and n, pick the e and n for which n × 10e - f is larger.
          2. Else fractionDigits is undefined,
            1. Let e, n, and f be integers such that f ≥ 0, 10f ≤ n < 10f + 1, the Number value for n × 10e - f is x, and f is as small as possible. Note that the decimal representation of n has f + 1 digits, n is not divisible by 10, and the least significant digit of n is not necessarily uniquely determined by these criteria.
          3. Let m be the String value consisting of the digits of the decimal representation of n (in order, with no leading zeroes).
        11. If f ≠ 0, then
          1. Let a be the first code unit of m, and let b be the remaining f code units of m.
          2. Set m to the string-concatenation of a, ".", and b.
        12. If e = 0, then
          1. Let c be "+".
          2. Let d be "0".
        13. Else,
          1. If e > 0, let c be "+".
          2. Else e ≤ 0,
            1. Let c be "-".
            2. Set e to -e.
          3. Let d be the String value consisting of the digits of the decimal representation of e (in order, with no leading zeroes).
        14. Set m to the string-concatenation of m, "e", c, and d.
        15. Return the string-concatenation of s and m.
        Note
        -

        For implementations that provide more accurate conversions -than required by the rules above, it is recommended that the following +

        For implementations that provide more accurate conversions +than required by the rules above, it is recommended that the following alternative version of step 10.b.i be used as a guideline:

        1. Let e, n, and f be integers such that f ≥ 0, 10f ≤ n < 10f + 1, the Number value for n × 10e - f is x, and f is as small as possible. If there are multiple possibilities for n, choose the value of n for which n × 10e - f is closest in value to x. If there are two such possible values of n, choose the one that is even.
        @@ -25143,10 +25143,10 @@ alternative version of step 10.b.i be used as a guideline:

       Note 2

      The output of toFixed may be more precise than toString - for some values because toString only prints enough significant digits + for some values because toString only prints enough significant digits to distinguish the number from adjacent number values. For example,

      (1000000000000000128).toString() returns "1000000000000000100", while - +
      (1000000000000000128).toFixed(0) returns "1000000000000000128".

       @@ -25155,23 +25155,23 @@ to distinguish the number from adjacent number values. For example,

      20.1.3.4Number.prototype.toLocaleString ( [ reserved1 [ , reserved2 ] ] )

      An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the Number.prototype.toLocaleString - method as specified in the ECMA-402 specification. If an ECMAScript -implementation does not include the ECMA-402 API the following + method as specified in the ECMA-402 specification. If an ECMAScript +implementation does not include the ECMA-402 API the following specification of the toLocaleString method is used.

      -

      Produces a String value that represents this Number value +

      Produces a String value that represents this Number value formatted according to the conventions of the host environment's current - locale. This function is implementation-dependent, and it is + locale. This function is implementation-dependent, and it is permissible, but not encouraged, for it to return the same thing as toString.

      -

      The meanings of the optional parameters to this method are -defined in the ECMA-402 specification; implementations that do not -include ECMA-402 support must not use those parameter positions for +

      The meanings of the optional parameters to this method are +defined in the ECMA-402 specification; implementations that do not +include ECMA-402 support must not use those parameter positions for anything else.

      20.1.3.5Number.prototype.toPrecision ( precision )

      -

      Return a String containing this Number value represented -either in decimal exponential notation with one digit before the +

      Return a String containing this Number value represented +either in decimal exponential notation with one digit before the significand's decimal point and precision - 1 digits after the significand's decimal point or in decimal fixed notation with precision significant digits. If precision is undefined, call ToString instead. Specifically, perform the following steps:

      1. Let x be ? thisNumberValue(this value).
      2. If precision is undefined, return ! ToString(x).
      3. Let p be ? ToInteger(precision).
      4. If x is NaN, return the String "NaN".
      5. Let s be the empty String.
      6. If x < 0, then
        1. Set s to the code unit 0x002D (HYPHEN-MINUS).
        2. Set x to -x.
      7. If x = +∞, then
        1. Return the string-concatenation of s and "Infinity".
      8. If p < 1 or p > 100, throw a RangeError exception.
      9. If x = 0, then
        1. Let m be the String value consisting of p occurrences of the code unit 0x0030 (DIGIT ZERO).
        2. Let e be 0.
      10. Else x ≠ 0,
        1. Let e and n be integers such that 10p - 1 ≤ n < 10p and for which the exact mathematical value of n × 10e - p + 1 - x is as close to zero as possible. If there are two such sets of e and n, pick the e and n for which n × 10e - p + 1 is larger.
        2. Let m be the String value consisting of the digits of the decimal representation of n (in order, with no leading zeroes).
        3. If e < -6 or e ≥ p, then
          1. Assert: e ≠ 0.
          2. If p ≠ 1, then
            1. Let a be the first code unit of m, and let b be the remaining p - 1 code units of m.
            2. Set m to the string-concatenation of a, ".", and b.
          3. If e > 0, then
            1. Let c be the code unit 0x002B (PLUS SIGN).
          4. Else e < 0,
            1. Let c be the code unit 0x002D (HYPHEN-MINUS).
            2. Set e to -e.
          5. Let d be the String value consisting of the digits of the decimal representation of e (in order, with no leading zeroes).
          6. Return the string-concatenation of s, m, the code unit 0x0065 (LATIN SMALL LETTER E), c, and d.
      11. If e = p - 1, return the string-concatenation of s and m.
      12. If e ≥ 0, then
        1. Set m to the string-concatenation of the first e + 1 code units of m, the code unit 0x002E (FULL STOP), and the remaining p - (e + 1) code units of m.
      13. Else e < 0,
        1. Set m to the string-concatenation of the code unit 0x0030 (DIGIT ZERO), the code unit 0x002E (FULL STOP), -(e + 1) occurrences of the code unit 0x0030 (DIGIT ZERO), and the String m.
      14. Return the string-concatenation of s and m.
      @@ -25185,7 +25185,7 @@ significand's decimal point and precision -

      The following steps are performed:

      1. Let x be ? thisNumberValue(this value).
      2. If radix is not present, let radixNumber be 10.
      3. Else if radix is undefined, let radixNumber be 10.
      4. Else, let radixNumber be ? ToInteger(radix).
      5. If radixNumber < 2 or radixNumber > 36, throw a RangeError exception.
      6. If radixNumber = 10, return ! ToString(x).
      7. Return the String representation of this Number value using the radix specified by radixNumber. Letters a-z are used for digits with values 10 through 35. The precise algorithm is - implementation-dependent, however the algorithm should be a + implementation-dependent, however the algorithm should be a generalization of that specified in 7.1.12.1.

      The toString function is not generic; it throws a TypeError exception if its this value is not a Number or a Number object. Therefore, it cannot be transferred to other kinds of objects for use as a method.

      @@ -25201,9 +25201,9 @@ generalization of that specified in

      20.1.4Properties of Number Instances

      -

      Number instances are ordinary objects that inherit properties -from the Number prototype object. Number instances also have a -[[NumberData]] internal slot. The [[NumberData]] internal slot is the +

      Number instances are ordinary objects that inherit properties +from the Number prototype object. Number instances also have a +[[NumberData]] internal slot. The [[NumberData]] internal slot is the Number value represented by this Number object.

       @@ -25295,22 +25295,22 @@ Number value represented by this Number object.

      20.2.2Function Properties of the Math Object

      Each of the following Math object functions applies the ToNumber abstract operation to each of its arguments (in left-to-right order if there is more than one). If ToNumber returns an abrupt completion, that Completion Record is immediately returned. Otherwise, the function performs a computation - on the resulting Number value(s). The value returned by each function + on the resulting Number value(s). The value returned by each function is a Number.

      In the function descriptions below, the symbols NaN, -0, +0, -∞ and +∞ refer to the Number values described in 6.1.6.

      Note

      The behaviour of the functions acos, acosh, asin, asinh, atan, atanh, atan2, cbrt, cos, cosh, exp, expm1, hypot, log,log1p, log2, log10, pow, random, sin, sinh, sqrt, tan, and tanh - is not precisely specified here except to require specific results for -certain argument values that represent boundary cases of interest. For -other argument values, these functions are intended to compute -approximations to the results of familiar mathematical functions, but -some latitude is allowed in the choice of approximation algorithms. The -general intent is that an implementer should be able to use the same + is not precisely specified here except to require specific results for +certain argument values that represent boundary cases of interest. For +other argument values, these functions are intended to compute +approximations to the results of familiar mathematical functions, but +some latitude is allowed in the choice of approximation algorithms. The +general intent is that an implementer should be able to use the same mathematical library for ECMAScript on a given hardware platform that is available to C programmers on that platform.

      -

      Although the choice of algorithms is left to the -implementation, it is recommended (but not specified by this standard) -that implementations use the approximation algorithms for IEEE 754-2008 +

      Although the choice of algorithms is left to the +implementation, it is recommended (but not specified by this standard) +that implementations use the approximation algorithms for IEEE 754-2008 arithmetic contained in fdlibm, the freely distributable mathematical library from Sun Microsystems (http://www.netlib.org/fdlibm).

       @@ -25320,15 +25320,15 @@ arithmetic contained in fdlibm, the freely distributable mathematic
      • If x is NaN, the result is NaN. - +
      • If x is -0, the result is +0. - +
      • If x is -∞, the result is +∞. - +
      @@ -25339,19 +25339,19 @@ arithmetic contained in fdlibm, the freely distributable mathematic
      • If x is NaN, the result is NaN. - +
      • If x is greater than 1, the result is NaN. - +
      • If x is less than -1, the result is NaN. - +
      • If x is exactly 1, the result is +0. - +
      @@ -25362,19 +25362,19 @@ arithmetic contained in fdlibm, the freely distributable mathematic
      • If x is NaN, the result is NaN. - +
      • If x is less than 1, the result is NaN. - +
      • If x is 1, the result is +0. - +
      • If x is +∞, the result is +∞. - +
      @@ -25385,23 +25385,23 @@ arithmetic contained in fdlibm, the freely distributable mathematic
      • If x is NaN, the result is NaN. - +
      • If x is greater than 1, the result is NaN. - +
      • If x is less than -1, the result is NaN. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      @@ -25412,23 +25412,23 @@ arithmetic contained in fdlibm, the freely distributable mathematic
      • If x is NaN, the result is NaN. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      • If x is +∞, the result is +∞. - +
      • If x is -∞, the result is -∞. - +
      @@ -25439,23 +25439,23 @@ arithmetic contained in fdlibm, the freely distributable mathematic
      • If x is NaN, the result is NaN. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      • If x is +∞, the result is an implementation-dependent approximation to +π / 2. - +
      • If x is -∞, the result is an implementation-dependent approximation to -π / 2. - +
      @@ -25466,31 +25466,31 @@ arithmetic contained in fdlibm, the freely distributable mathematic
      • If x is NaN, the result is NaN. - +
      • If x is less than -1, the result is NaN. - +
      • If x is greater than 1, the result is NaN. - +
      • If x is -1, the result is -∞. - +
      • If x is +1, the result is +∞. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      @@ -25498,101 +25498,101 @@ arithmetic contained in fdlibm, the freely distributable mathematic

      20.2.2.8Math.atan2 ( y, x )

      Returns an implementation-dependent approximation to the arc tangent of the quotient y / x of the arguments y and x, where the signs of y and x - are used to determine the quadrant of the result. Note that it is -intentional and traditional for the two-argument arc tangent function + are used to determine the quadrant of the result. Note that it is +intentional and traditional for the two-argument arc tangent function that the argument named y be first and the argument named x be second. The result is expressed in radians and ranges from -π to +π.

      • If either x or y is NaN, the result is NaN. - +
      • If y > 0 and x is +0, the result is an implementation-dependent approximation to +π / 2. - +
      • If y > 0 and x is -0, the result is an implementation-dependent approximation to +π / 2. - +
      • If y is +0 and x > 0, the result is +0. - +
      • If y is +0 and x is +0, the result is +0. - +
      • If y is +0 and x is -0, the result is an implementation-dependent approximation to +π. - +
      • If y is +0 and x < 0, the result is an implementation-dependent approximation to +π. - +
      • If y is -0 and x > 0, the result is -0. - +
      • If y is -0 and x is +0, the result is -0. - +
      • If y is -0 and x is -0, the result is an implementation-dependent approximation to -π. - +
      • If y is -0 and x < 0, the result is an implementation-dependent approximation to -π. - +
      • If y < 0 and x is +0, the result is an implementation-dependent approximation to -π / 2. - +
      • If y < 0 and x is -0, the result is an implementation-dependent approximation to -π / 2. - +
      • If y > 0 and y is finite and x is +∞, the result is +0. - +
      • If y > 0 and y is finite and x is -∞, the result is an implementation-dependent approximation to +π. - +
      • If y < 0 and y is finite and x is +∞, the result is -0. - +
      • If y < 0 and y is finite and x is -∞, the result is an implementation-dependent approximation to -π. - +
      • If y is +∞ and x is finite, the result is an implementation-dependent approximation to +π / 2. - +
      • If y is -∞ and x is finite, the result is an implementation-dependent approximation to -π / 2. - +
      • If y is +∞ and x is +∞, the result is an implementation-dependent approximation to +π / 4. - +
      • If y is +∞ and x is -∞, the result is an implementation-dependent approximation to +3π / 4. - +
      • If y is -∞ and x is +∞, the result is an implementation-dependent approximation to -π / 4. - +
      • If y is -∞ and x is -∞, the result is an implementation-dependent approximation to -3π / 4. - +
      @@ -25603,23 +25603,23 @@ that the argument named y be first and the argument named x
    5. If x is NaN, the result is NaN. - +
    6. If x is +0, the result is +0. - +
    7. If x is -0, the result is -0. - +
    8. If x is +∞, the result is +∞. - +
    9. If x is -∞, the result is -∞. - +
      10. @@ -25630,27 +25630,27 @@ that the argument named y be first and the argument named x
    10. If x is NaN, the result is NaN. - +
    11. If x is +0, the result is +0. - +
    12. If x is -0, the result is -0. - +
    13. If x is +∞, the result is +∞. - +
    14. If x is -∞, the result is -∞. - +
    15. If x is less than 0 but greater than -1, the result is -0. - +

      16. The value of Math.ceil(x) is the same as the value of -Math.floor(-x).

      @@ -25672,23 +25672,23 @@ that the argument named y be first and the argument named x
    16. If x is NaN, the result is NaN. - +
    17. If x is +0, the result is 1. - +
    18. If x is -0, the result is 1. - +
    19. If x is +∞, the result is NaN. - +
    20. If x is -∞, the result is NaN. - +
      21. @@ -25699,23 +25699,23 @@ that the argument named y be first and the argument named x
    21. If x is NaN, the result is NaN. - +
    22. If x is +0, the result is 1. - +
    23. If x is -0, the result is 1. - +
    24. If x is +∞, the result is +∞. - +
    25. If x is -∞, the result is +∞. - +
      26. Note
      @@ -25729,23 +25729,23 @@ that the argument named y be first and the argument named x
    26. If x is NaN, the result is NaN. - +
    27. If x is +0, the result is 1. - +
    28. If x is -0, the result is 1. - +
    29. If x is +∞, the result is +∞. - +
    30. If x is -∞, the result is +0. - +
      31. @@ -25756,23 +25756,23 @@ that the argument named y be first and the argument named x
    31. If x is NaN, the result is NaN. - +
    32. If x is +0, the result is +0. - +
    33. If x is -0, the result is -0. - +
    34. If x is +∞, the result is +∞. - +
    35. If x is -∞, the result is -1. - +
      36. @@ -25783,27 +25783,27 @@ that the argument named y be first and the argument named x
    36. If x is NaN, the result is NaN. - +
    37. If x is +0, the result is +0. - +
    38. If x is -0, the result is -0. - +
    39. If x is +∞, the result is +∞. - +
    40. If x is -∞, the result is -∞. - +
    41. If x is greater than 0 but less than 1, the result is +0. - +
      42. Note
      @@ -25824,29 +25824,29 @@ that the argument named y be first and the argument named x
    42. If no arguments are passed, the result is +0. - +
    43. If any argument is +∞, the result is +∞. - +
    44. If any argument is -∞, the result is +∞. - +
    45. If no argument is +∞ or -∞, and any argument is NaN, the result is NaN. - +
    46. If all arguments are either +0 or -0, the result is +0. - +
      47. Note
      -

      Implementations should take care to avoid the loss of +

      Implementations should take care to avoid the loss of precision from overflows and underflows that are prone to occur in naive - implementations when this function is called with two or more + implementations when this function is called with two or more arguments.

       @@ -25864,23 +25864,23 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is less than 0, the result is NaN. - +
      • If x is +0 or -0, the result is -∞. - +
      • If x is 1, the result is +0. - +
      • If x is +∞, the result is +∞. - +
      @@ -25891,27 +25891,27 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is less than -1, the result is NaN. - +
      • If x is -1, the result is -∞. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      • If x is +∞, the result is +∞. - +
      @@ -25922,27 +25922,27 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is less than 0, the result is NaN. - +
      • If x is +0, the result is -∞. - +
      • If x is -0, the result is -∞. - +
      • If x is 1, the result is +0. - +
      • If x is +∞, the result is +∞. - +
      @@ -25953,27 +25953,27 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is less than 0, the result is NaN. - +
      • If x is +0, the result is -∞. - +
      • If x is -0, the result is -∞. - +
      • If x is 1, the result is +0. - +
      • If x is +∞, the result is +∞. - +
      @@ -25984,15 +25984,15 @@ arguments.

      • If no arguments are given, the result is -∞. - +
      • If any value is NaN, the result is NaN. - +
      • The comparison of values to determine the largest value is done using the Abstract Relational Comparison algorithm except that +0 is considered to be larger than -0. - +
      @@ -26003,15 +26003,15 @@ arguments.

      • If no arguments are given, the result is +∞. - +
      • If any value is NaN, the result is NaN. - +
      • The comparison of values to determine the smallest value is done using the Abstract Relational Comparison algorithm except that +0 is considered to be larger than -0. - +
      @@ -26024,10 +26024,10 @@ arguments.

      20.2.2.27Math.random ( )

      -

      Returns a Number value with positive sign, greater than or -equal to 0 but less than 1, chosen randomly or pseudo randomly with -approximately uniform distribution over that range, using an -implementation-dependent algorithm or strategy. This function takes no +

      Returns a Number value with positive sign, greater than or +equal to 0 but less than 1, chosen randomly or pseudo randomly with +approximately uniform distribution over that range, using an +implementation-dependent algorithm or strategy. This function takes no arguments.

      Each Math.random function created for distinct realms must produce a distinct sequence of values from successive calls.

       @@ -26038,31 +26038,31 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      • If x is +∞, the result is +∞. - +
      • If x is -∞, the result is -∞. - +
      • If x is greater than 0 but less than 0.5, the result is +0. - +
      • If x is less than 0 but greater than or equal to -0.5, the result is -0. - +
      Note 1
      @@ -26079,23 +26079,23 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is -0, the result is -0. - +
      • If x is +0, the result is +0. - +
      • If x is negative and not -0, the result is -1. - +
      • If x is positive and not +0, the result is +1. - +
      @@ -26106,19 +26106,19 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      • If x is +∞ or -∞, the result is NaN. - +
      @@ -26129,23 +26129,23 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      • If x is +∞, the result is +∞. - +
      • If x is -∞, the result is -∞. - +
      Note
      @@ -26159,23 +26159,23 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is less than 0, the result is NaN. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      • If x is +∞, the result is +∞. - +
      @@ -26186,19 +26186,19 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      • If x is +∞ or -∞, the result is NaN. - +
      @@ -26209,23 +26209,23 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is +0, the result is +0. - +
      • If x is -0, the result is -0. - +
      • If x is +∞, the result is +1. - +
      • If x is -∞, the result is -1. - +
      Note
      @@ -26239,31 +26239,31 @@ arguments.

      • If x is NaN, the result is NaN. - +
      • If x is -0, the result is -0. - +
      • If x is +0, the result is +0. - +
      • If x is +∞, the result is +∞. - +
      • If x is -∞, the result is -∞. - +
      • If x is greater than 0 but less than 1, the result is +0. - +
      • If x is less than 0 but greater than -1, the result is -0. - +
      @@ -26281,25 +26281,25 @@ arguments.

      20.3.1.1Time Values and Time Range

      A Date object contains a Number representing an instant in time with millisecond precision. Such a Number is called a time value. A time value may also be NaN, indicating that the Date object does not represent a specific instant in time.

      Time is measured in ECMAScript as milliseconds since midnight - at the beginning of 01 January, 1970 UTC. Time in ECMAScript does not -observe leap seconds; they are ignored. Time calculations assume each + at the beginning of 01 January, 1970 UTC. Time in ECMAScript does not +observe leap seconds; they are ignored. Time calculations assume each and every day contains exactly 60 × 60 × 24 × 1000 = 86,400,000 milliseconds, to align with the POSIX specification of each and every day containing exactly 86,400 seconds.

      A Number can exactly represent all integers from -9,007,199,254,740,992 to 9,007,199,254,740,992 (20.1.2.8 and 20.1.2.6). - A time value supports a slightly smaller range of exactly -100,000,000 -days to 100,000,000 days measured relative to midnight at the beginning + A time value supports a slightly smaller range of exactly -100,000,000 +days to 100,000,000 days measured relative to midnight at the beginning of 01 January, 1970 UTC. This yields an exact supported time value range - of -8,640,000,000,000,000 to 8,640,000,000,000,000 milliseconds + of -8,640,000,000,000,000 to 8,640,000,000,000,000 milliseconds relative to midnight at the beginning of 01 January, 1970 UTC.

      The exact moment of midnight at the beginning of 01 January, 1970 UTC is represented by the time value +0.

      Note
      -

      The 400 year cycle of the Gregorian calendar contains 97 -leap years. This yields an average of 365.2425 days per year, or an -average of 31,556,952,000 milliseconds per year under the Gregorian +

      The 400 year cycle of the Gregorian calendar contains 97 +leap years. This yields an average of 365.2425 days per year, or an +average of 31,556,952,000 milliseconds per year under the Gregorian calendar. ECMAScript applies a proleptic Gregorian calendar for all time computations.

      -

      As specified by this section, the maximum year range a +

      As specified by this section, the maximum year range a Number can represent exactly with millisecond precision is approximately - -285,426 to 285,426 years relative to midnight at the beginning of 01 + -285,426 to 285,426 years relative to midnight at the beginning of 01 January, 1970 UTC.

      As specified by this section, the maximum year range a time value can represent is approximately -273,790 to 273,790 years relative @@ -26319,14 +26319,14 @@ January, 1970 UTC.

      20.3.1.3Year Number

      -

      ECMAScript uses a proleptic Gregorian calendar to map a day -number to a year number and to determine the month and date within that -year. In this calendar, leap years are precisely those which are +

      ECMAScript uses a proleptic Gregorian calendar to map a day +number to a year number and to determine the month and date within that +year. In this calendar, leap years are precisely those which are (divisible by 4) and ((not divisible by 100) or (divisible by 400)). The number of days in year number y is therefore defined by

      DaysInYear(y)
      = 365 if (y modulo 4) ≠ 0
      = 366 if (y modulo 4) = 0 and (y modulo 100) ≠ 0
      = 365 if (y modulo 100) = 0 and (y modulo 400) ≠ 0
      = 366 if (y modulo 400) = 0
       -

      All non-leap years have 365 days with the usual number of -days per month and leap years have an extra day in February. The day +

      All non-leap years have 365 days with the usual number of +days per month and leap years have an extra day in February. The day number of the first day of year y is given by:

      DayFromYear(y) = 365 × (y - 1970) + floor((y - 1969) / 4) - floor((y - 1901) / 100) + floor((y - 1601) / 400)

      The time value of the start of a year is:

      @@ -26345,7 +26345,7 @@ number of the first day of year y is given by:

      DayWithinYear(t) = Day(t) - DayFromYear(YearFromTime(t))

      A month value of 0 specifies January; 1 specifies February; 2 specifies March; 3 specifies April; 4 specifies May; 5 specifies June; 6 - specifies July; 7 specifies August; 8 specifies September; 9 specifies + specifies July; 7 specifies August; 8 specifies September; 9 specifies October; 10 specifies November; and 11 specifies December. Note that MonthFromTime(0) = 0, corresponding to Thursday, 01 January, 1970.

       @@ -26359,22 +26359,22 @@ October; 10 specifies November; and 11 specifies December. Note that 20.3.1.6Week Day

      The weekday for a particular time value t is defined as

      WeekDay(t) = (Day(t) + 4) modulo 7
       -

      A weekday value of 0 specifies Sunday; 1 specifies Monday; 2 -specifies Tuesday; 3 specifies Wednesday; 4 specifies Thursday; 5 +

      A weekday value of 0 specifies Sunday; 1 specifies Monday; 2 +specifies Tuesday; 3 specifies Wednesday; 4 specifies Thursday; 5 specifies Friday; and 6 specifies Saturday. Note that WeekDay(0) = 4, corresponding to Thursday, 01 January, 1970.

      20.3.1.7LocalTZA ( t, isUTC )

      -

      LocalTZA( t, isUTC ) is an -implementation-defined algorithm that must return a number representing -milliseconds suitable for adding to a Time Value. The local political +

      LocalTZA( t, isUTC ) is an +implementation-defined algorithm that must return a number representing +milliseconds suitable for adding to a Time Value. The local political rules for standard time and daylight saving time in effect at t should be used to determine the result in the way specified in the following three paragraphs.

      When isUTC is true, LocalTZA( t, true ) should return the offset of the local time zone from UTC measured in milliseconds at time represented by time value t (UTC). When the result is added to t (UTC), it should yield the local time.

      When isUTC is false, LocalTZA( t, false ) should return the offset of the local time zone from UTC measured in milliseconds at local time represented by time value tlocal = t. When the result is subtracted from the local time tlocal, it should yield the corresponding UTC.

      When tlocal - represents local time repeating multiple times at a negative time zone -transition (e.g. when the daylight saving time ends or the time zone + represents local time repeating multiple times at a negative time zone +transition (e.g. when the daylight saving time ends or the time zone adjustment is decreased due to a time zone rule change) or skipped local time at a positive time zone transitions (e.g. when the daylight saving time starts or the time zone adjustment is increased due to a time zone @@ -26383,10 +26383,10 @@ adjustment is decreased due to a time zone rule change) or skipped local Note

      It is recommended that implementations use the time zone information of the IANA Time Zone Database https://www.iana.org/time-zones/.

      1:30 AM on November 5, 2017 in America/New_York is repeated - twice (fall backward), but it must be interpreted as 1:30 AM UTC-04 + twice (fall backward), but it must be interpreted as 1:30 AM UTC-04 instead of 1:30 AM UTC-05. LocalTZA(TimeClip(MakeDate(MakeDay(2017, 10, 5), MakeTime(1, 30, 0, 0))), false) is -4 × msPerHour.

      -

      2:30 AM on March 12, 2017 in America/New_York does not -exist, but it must be interpreted as 2:30 AM UTC-05 (equivalent to 3:30 +

      2:30 AM on March 12, 2017 in America/New_York does not +exist, but it must be interpreted as 2:30 AM UTC-05 (equivalent to 3:30 AM UTC-04). LocalTZA(TimeClip(MakeDate(MakeDay(2017, 2, 12), MakeTime(2, 30, 0, 0))), false) is -5 × msPerHour.

       @@ -26398,8 +26398,8 @@ AM UTC-04). LocalTZA(Note

      Two different time values (t (UTC)) are converted to the same local time tlocal - at a negative time zone transition when there are repeated times (e.g. -the daylight saving time ends or the time zone adjustment is + at a negative time zone transition when there are repeated times (e.g. +the daylight saving time ends or the time zone adjustment is decreased.).

      @@ -26432,8 +26432,8 @@ decreased.).

      20.3.1.11MakeTime ( hour, min, sec, ms )

      -

      The abstract operation MakeTime calculates a number of -milliseconds from its four arguments, which must be ECMAScript Number +

      The abstract operation MakeTime calculates a number of +milliseconds from its four arguments, which must be ECMAScript Number values. This operator functions as follows:

      1. If hour is not finite or min is not finite or sec is not finite or ms is not finite, return NaN.
      2. Let h be ! ToInteger(hour).
      3. Let m be ! ToInteger(min).
      4. Let s be ! ToInteger(sec).
      5. Let milli be ! ToInteger(ms).
      6. Let t be h * msPerHour + m * msPerMinute + s * msPerSecond + milli, performing the arithmetic according to IEEE 754-2008 rules (that is, as if using the ECMAScript operators * and +).
      7. Return t.
      @@ -26441,8 +26441,8 @@ values. This operator functions as follows:

      20.3.1.12MakeDay ( year, month, date )

      -

      The abstract operation MakeDay calculates a number of days -from its three arguments, which must be ECMAScript Number values. This +

      The abstract operation MakeDay calculates a number of days +from its three arguments, which must be ECMAScript Number values. This operator functions as follows:

      1. If year is not finite or month is not finite or date is not finite, return NaN.
      2. Let y be ! ToInteger(year).
      3. Let m be ! ToInteger(month).
      4. Let dt be ! ToInteger(date).
      5. Let ym be y + floor(m / 12).
      6. Let mn be m modulo 12.
      7. Find a value t such that YearFromTime(t) is ym and MonthFromTime(t) is mn and DateFromTime(t) is 1; but if this is not possible (because some argument is out of range), return NaN.
      8. Return Day(t) + dt - 1.
      @@ -26450,8 +26450,8 @@ operator functions as follows:

      20.3.1.13MakeDate ( day, time )

      -

      The abstract operation MakeDate calculates a number of -milliseconds from its two arguments, which must be ECMAScript Number +

      The abstract operation MakeDate calculates a number of +milliseconds from its two arguments, which must be ECMAScript Number values. This operator functions as follows:

      1. If day is not finite or time is not finite, return NaN.
      2. Return day × msPerDay + time.
      @@ -26459,16 +26459,16 @@ values. This operator functions as follows:

      20.3.1.14TimeClip ( time )

      -

      The abstract operation TimeClip calculates a number of -milliseconds from its argument, which must be an ECMAScript Number +

      The abstract operation TimeClip calculates a number of +milliseconds from its argument, which must be an ECMAScript Number value. This operator functions as follows:

      1. If time is not finite, return NaN.
      2. If abs(time) > 8.64 × 1015, return NaN.
      3. Let clippedTime be ! ToInteger(time).
      4. If clippedTime is -0, set clippedTime to +0.
      5. Return clippedTime.
      Note

      The point of step 4 is that an implementation is permitted a - choice of internal representations of time values, for example as a -64-bit signed integer or as a 64-bit floating-point value. Depending on -the implementation, this internal representation may or may not + choice of internal representations of time values, for example as a +64-bit signed integer or as a 64-bit floating-point value. Depending on +the implementation, this internal representation may or may not distinguish -0 and +0.

             @@ -26476,7 +26476,7 @@ distinguish -0 and +0.

      20.3.1.15Date Time String Format

      ECMAScript defines a string interchange format for date-times - based upon a simplification of the ISO 8601 calendar date extended + based upon a simplification of the ISO 8601 calendar date extended format. The format is as follows: YYYY-MM-DDTHH:mm:ss.sssZ

      Where the fields are as follows:

      @@ -26485,121 +26485,121 @@ format. The format is as follows: YYYY-MM-DDTHH:mm:ss.sssZ

       @@ -26623,30 +26623,30 @@ THH:mm:ss.sss

      A string containing out-of-bounds or nonconforming fields is not a valid instance of this format.

      Note 1

      As every day both starts and ends with midnight, the two notations 00:00 and 24:00 - are available to distinguish the two midnights that can be associated -with one date. This means that the following two notations refer to + are available to distinguish the two midnights that can be associated +with one date. This means that the following two notations refer to exactly the same point in time: 1995-02-04T24:00 and 1995-02-05T00:00. - This interpretation of the latter form as "end of a calendar day" is + This interpretation of the latter form as "end of a calendar day" is consistent with ISO 8601, even though that specification reserves it for describing time intervals and does not permit it within representations of single points in time.

       Note 2
      -

      There exists no international standard that specifies +

      There exists no international standard that specifies abbreviations for civil time zones like CET, EST, etc. and sometimes the - same abbreviation is even used for two very different time zones. For -this reason, both ISO 8601 and this format specify numeric + same abbreviation is even used for two very different time zones. For +this reason, both ISO 8601 and this format specify numeric representations of time zone offsets.

      20.3.1.15.1Expanded Years

      Covering the full time value range of approximately 273,790 years forward or backward from 01 January, 1970 (20.3.1.1) - requires representing years before 0 or after 9999. ISO 8601 permits -expansion of the year representation, but only by mutual agreement of -the partners in information interchange. In the simplified ECMAScript -format, such an expanded year representation shall have 6 digits and is -always prefixed with a + or - sign. The year 0 is considered positive + requires representing years before 0 or after 9999. ISO 8601 permits +expansion of the year representation, but only by mutual agreement of +the partners in information interchange. In the simplified ECMAScript +format, such an expanded year representation shall have 6 digits and is +always prefixed with a + or - sign. The year 0 is considered positive and hence prefixed with a + sign. Strings matching the Date Time String Format with expanded years representing instants in time outside the range of a time value are treated as unrecognizable by Date.parse and cause that function to return NaN without falling back to implementation-specific behavior or heuristics.

      Note

      Examples of date-time values with expanded years:

      @@ -26743,18 +26743,18 @@ and hence prefixed with a + sign. Strings matching the

      20.3.3.2Date.parse ( string )

      The parse function applies the ToString operator to its argument. If ToString results in an abrupt completion the Completion Record is immediately returned. Otherwise, parse interprets the resulting String as a date and time; it returns a Number, the UTC time value - corresponding to the date and time. The String may be interpreted as a -local time, a UTC time, or a time in some other time zone, depending on -the contents of the String. The function first attempts to parse the + corresponding to the date and time. The String may be interpreted as a +local time, a UTC time, or a time in some other time zone, depending on +the contents of the String. The function first attempts to parse the String according to the format described in Date Time String Format (20.3.1.15), including expanded years. If the String does not conform to that format the function may fall back to any implementation-specific heuristics or - implementation-specific date formats. Strings that are unrecognizable + implementation-specific date formats. Strings that are unrecognizable or contain out-of-bounds format field values shall cause Date.parse to return NaN.

      -

      If x is any Date object whose milliseconds -amount is zero within a particular implementation of ECMAScript, then -all of the following expressions should produce the same numeric value -in that implementation, if all the properties referenced have their +

      If x is any Date object whose milliseconds +amount is zero within a particular implementation of ECMAScript, then +all of the following expressions should produce the same numeric value +in that implementation, if all the properties referenced have their initial values:

      x.valueOf()
 Date.parse(x.toString())
@@ -27084,7 +27084,7 @@ initial values:
      
       
         
      20.3.4.36Date.prototype.toISOString ( )
      
         
      This function returns a String value representing the instance in time corresponding to this time value. The format of the String is the Date Time string format defined in  20.3.1.15. All fields are present in the String. The time zone is always UTC, denoted by the suffix Z. If this time value
- is not a finite Number or if the year is not a value that can be 
+ is not a finite Number or if the year is not a value that can be
 represented in that format (if necessary using expanded year format), a RangeError exception is thrown.
      
             
 
@@ -27100,7 +27100,7 @@ represented in that format (if necessary using expanded year format), a Note 2
      
           
      The toJSON function is intentionally generic; it does not require that its this
  value be a Date object. Therefore, it can be transferred to other kinds
- of objects for use as a method. However, it does require that any such 
+ of objects for use as a method. However, it does require that any such
 object have a toISOString method.
      
         
      
       
@@ -27108,50 +27108,50 @@ object have a toISOString method.
      
       
         
      20.3.4.38Date.prototype.toLocaleDateString ( [ reserved1 [ , reserved2 ] ] )
      
         
      An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the Date.prototype.toLocaleDateString
- method as specified in the ECMA-402 specification. If an ECMAScript 
-implementation does not include the ECMA-402 API the following 
+ method as specified in the ECMA-402 specification. If an ECMAScript
+implementation does not include the ECMA-402 API the following
 specification of the toLocaleDateString method is used.
      
-        
      This function returns a String value. The contents of the 
-String are implementation-dependent, but are intended to represent the 
-“date” portion of the Date in the current time zone in a convenient, 
-human-readable form that corresponds to the conventions of the host 
+        
      This function returns a String value. The contents of the
+String are implementation-dependent, but are intended to represent the
+“date” portion of the Date in the current time zone in a convenient,
+human-readable form that corresponds to the conventions of the host
 environment's current locale.
      
-        
      The meaning of the optional parameters to this method are 
-defined in the ECMA-402 specification; implementations that do not 
-include ECMA-402 support must not use those parameter positions for 
+        
      The meaning of the optional parameters to this method are
+defined in the ECMA-402 specification; implementations that do not
+include ECMA-402 support must not use those parameter positions for
 anything else.
      
             
 
       
         
      20.3.4.39Date.prototype.toLocaleString ( [ reserved1 [ , reserved2 ] ] )
      
         
      An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the Date.prototype.toLocaleString
- method as specified in the ECMA-402 specification. If an ECMAScript 
-implementation does not include the ECMA-402 API the following 
+ method as specified in the ECMA-402 specification. If an ECMAScript
+implementation does not include the ECMA-402 API the following
 specification of the toLocaleString method is used.
      
-        
      This function returns a String value. The contents of the 
-String are implementation-dependent, but are intended to represent the 
-Date in the current time zone in a convenient, human-readable form that 
+        
      This function returns a String value. The contents of the
+String are implementation-dependent, but are intended to represent the
+Date in the current time zone in a convenient, human-readable form that
 corresponds to the conventions of the host environment's current locale.
      
-        
      The meaning of the optional parameters to this method are 
-defined in the ECMA-402 specification; implementations that do not 
-include ECMA-402 support must not use those parameter positions for 
+        
      The meaning of the optional parameters to this method are
+defined in the ECMA-402 specification; implementations that do not
+include ECMA-402 support must not use those parameter positions for
 anything else.
      
             
 
       
         
      20.3.4.40Date.prototype.toLocaleTimeString ( [ reserved1 [ , reserved2 ] ] )
      
         
      An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the Date.prototype.toLocaleTimeString
- method as specified in the ECMA-402 specification. If an ECMAScript 
-implementation does not include the ECMA-402 API the following 
+ method as specified in the ECMA-402 specification. If an ECMAScript
+implementation does not include the ECMA-402 API the following
 specification of the toLocaleTimeString method is used.
      
-        
      This function returns a String value. The contents of the 
-String are implementation-dependent, but are intended to represent the 
-“time” portion of the Date in the current time zone in a convenient, 
-human-readable form that corresponds to the conventions of the host 
+        
      This function returns a String value. The contents of the
+String are implementation-dependent, but are intended to represent the
+“time” portion of the Date in the current time zone in a convenient,
+human-readable form that corresponds to the conventions of the host
 environment's current locale.
      
-        
      The meaning of the optional parameters to this method are 
-defined in the ECMA-402 specification; implementations that do not 
-include ECMA-402 support must not use those parameter positions for 
+        
      The meaning of the optional parameters to this method are
+defined in the ECMA-402 specification; implementations that do not
+include ECMA-402 support must not use those parameter positions for
 anything else.
      
             
 
@@ -27185,81 +27185,81 @@ anything else.
      @@ -27271,131 +27271,131 @@ anything else.

       @@ -27407,8 +27407,8 @@ anything else.

      20.3.4.41.3Runtime Semantics: TimeZoneString ( tv )

      The following steps are performed:

      1. Assert: Type(tv) is Number.
      2. Assert: tv is not NaN.
      3. Let offset be LocalTZA(tv, true).
      4. If offset ≥ 0, let offsetSign be "+"; otherwise, let offsetSign be "-".
      5. Let offsetMin be the String representation of MinFromTime(abs(offset)), formatted as a two-digit decimal number, padded to the left with a zero if necessary.
      6. Let offsetHour be the String representation of HourFromTime(abs(offset)), formatted as a two-digit decimal number, padded to the left with a zero if necessary.
      7. Let tzName be an implementation-defined string that is either the empty string or the string-concatenation - of the code unit 0x0020 (SPACE), the code unit 0x0028 (LEFT -PARENTHESIS), an implementation-dependent timezone name, and the code + of the code unit 0x0020 (SPACE), the code unit 0x0028 (LEFT +PARENTHESIS), an implementation-dependent timezone name, and the code unit 0x0029 (RIGHT PARENTHESIS).
      8. Return the string-concatenation of offsetSign, offsetHour, offsetMin, and tzName.
      @@ -27455,7 +27455,7 @@ unit 0x0029 (RIGHT PARENTHESIS).
    47. Return the

      20.3.5Properties of Date Instances

      -

      Date instances are ordinary objects that inherit properties +

      Date instances are ordinary objects that inherit properties from the Date prototype object. Date instances also have a [[DateValue]] internal slot. The [[DateValue]] internal slot is the time value represented by this Date object.

      @@ -27521,12 +27521,12 @@ from the Date prototype object. Date instances also have a [[DateValue]]

      21.1.2.4String.raw ( template, ...substitutions )

      The String.raw function may be called with a variable number of arguments. The first argument is template and the remainder of the arguments form the List substitutions. The following steps are taken:

      1. Let substitutions be a List - consisting of all of the arguments passed to this function, starting + consisting of all of the arguments passed to this function, starting with the second argument. If fewer than two arguments were passed, the List is empty.
      2. Let numberOfSubstitutions be the number of elements in substitutions.
      3. Let cooked be ? ToObject(template).
      4. Let raw be ? ToObject(? Get(cooked, "raw")).
      5. Let literalSegments be ? ToLength(? Get(raw, "length")).
      6. If literalSegments ≤ 0, return the empty string.
      7. Let stringElements be a new empty List.
      8. Let nextIndex be 0.
      9. Repeat,
        1. Let nextKey be ! ToString(nextIndex).
        2. Let nextSeg be ? ToString(? Get(raw, nextKey)).
        3. Append in order the code unit elements of nextSeg to the end of stringElements.
        4. If nextIndex + 1 = literalSegments, then
          1. Return the String value whose code units are, in order, the elements in the List stringElements. If stringElements has no elements, the empty string is returned.
        5. If nextIndex < numberOfSubstitutions, let next be substitutions[nextIndex].
        6. Else, let next be the empty String.
        7. Let nextSub be ? ToString(next).
        8. Append in order the code unit elements of nextSub to the end of stringElements.
        9. Increase nextIndex by 1.
      Note

      String.raw is intended for use as a tag function of a Tagged Template (12.3.7). - When called as such, the first argument will be a well formed template + When called as such, the first argument will be a well formed template object and the rest parameter will contain the substitution values.

       @@ -27543,7 +27543,7 @@ object and the rest parameter will contain the substitution values.

    48. has a [[Prototype]] internal slot whose value is the intrinsic object %ObjectPrototype%.

      49. Unless explicitly stated otherwise, the methods of the String prototype object defined below are not generic and the this - value passed to them must be either a String value or an object that + value passed to them must be either a String value or an object that has a [[StringData]] internal slot that has been initialized to a String value.

      The abstract operation thisStringValue(value) performs the following steps:

      @@ -27554,8 +27554,8 @@ has a [[StringData]] internal slot that has been initialized to a String

      21.1.3.1String.prototype.charAt ( pos )

      Note 1

      Returns a single element String containing the code unit at index pos - within the String value resulting from converting this object to a -String. If there is no element at that index, the result is the empty + within the String value resulting from converting this object to a +String. If there is no element at that index, the result is the empty String. The result is a String value, not a String object.

      If pos is a value of Number type that is an integer, then the result of x.charAt(pos) is equal to the result of x.substring(pos, pos + 1).

       @@ -27597,7 +27597,7 @@ String. The result is a String value, not a String object.

      21.1.3.4String.prototype.concat ( ...args )

      Note 1

      When the concat method is called it returns the String value consisting of the code units of the this - object (converted to a String) followed by the code units of each of + object (converted to a String) followed by the code units of each of the arguments converted to a String. The result is a String value, not a String object.

       @@ -27624,8 +27624,8 @@ the arguments converted to a String. The result is a String value, not a

      Returns true if the sequence of code units of searchString converted to a String is the same as the corresponding code units of this object (converted to a String) starting at endPosition - length(this). Otherwise returns false.

      Note 2
      -

      Throwing an exception if the first argument is a RegExp is -specified in order to allow future editions to define extensions that +

      Throwing an exception if the first argument is a RegExp is +specified in order to allow future editions to define extensions that allow such argument values.

       Note 3
      @@ -27639,13 +27639,13 @@ allow such argument values.

      1. Let O be ? RequireObjectCoercible(this value).
      2. Let S be ? ToString(O).
      3. Let isRegExp be ? IsRegExp(searchString).
      4. If isRegExp is true, throw a TypeError exception.
      5. Let searchStr be ? ToString(searchString).
      6. Let pos be ? ToInteger(position).
      7. Assert: If position is undefined, then pos is 0.
      8. Let len be the length of S.
      9. Let start be min(max(pos, 0), len).
      10. Let searchLen be the length of searchStr.
      11. If there exists any integer k not smaller than start such that k + searchLen is not greater than len, and for all nonnegative integers j less than searchLen, the code unit at index k + j within S is the same as the code unit at index j within searchStr, return true; but if there is no such integer k, return false.
      Note 1
      -

      If searchString appears as a substring of the -result of converting this object to a String, at one or more indices +

      If searchString appears as a substring of the +result of converting this object to a String, at one or more indices that are greater than or equal to position, return true; otherwise, returns false. If position is undefined, 0 is assumed, so as to search all of the String.

       Note 2
      -

      Throwing an exception if the first argument is a RegExp is -specified in order to allow future editions to define extensions that +

      Throwing an exception if the first argument is a RegExp is +specified in order to allow future editions to define extensions that allow such argument values.

       Note 3
      @@ -27656,8 +27656,8 @@ allow such argument values.

      21.1.3.8String.prototype.indexOf ( searchString [ , position ] )

      Note 1
      -

      If searchString appears as a substring of the -result of converting this object to a String, at one or more indices +

      If searchString appears as a substring of the +result of converting this object to a String, at one or more indices that are greater than or equal to position, then the smallest such index is returned; otherwise, -1 is returned. If position is undefined, 0 is assumed, so as to search all of the String.

      The indexOf method takes two arguments, searchString and position, and performs the following steps:

      @@ -27671,7 +27671,7 @@ that are greater than or equal to position, then the smallest such in

      21.1.3.9String.prototype.lastIndexOf ( searchString [ , position ] )

      Note 1
      -

      If searchString appears as a substring of the +

      If searchString appears as a substring of the result of converting this object to a String at one or more indices that are smaller than or equal to position, then the greatest such index is returned; otherwise, -1 is returned. If position is undefined, the length of the String value is assumed, so as to search all of the String.

       @@ -27686,41 +27686,41 @@ result of converting this object to a String at one or more indices that

      21.1.3.10String.prototype.localeCompare ( that [ , reserved1 [ , reserved2 ] ] )

      An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the localeCompare - method as specified in the ECMA-402 specification. If an ECMAScript -implementation does not include the ECMA-402 API the following + method as specified in the ECMA-402 specification. If an ECMAScript +implementation does not include the ECMA-402 API the following specification of the localeCompare method is used.

      When the localeCompare method is called with argument that, it returns a Number other than NaN that represents the result of a locale-sensitive String comparison of the this value (converted to a String) with that (converted to a String). The two Strings are S and That. - The two Strings are compared in an implementation-defined fashion. The + The two Strings are compared in an implementation-defined fashion. The result is intended to order String values in the sort order specified by - a host default locale, and will be negative, zero, or positive, + a host default locale, and will be negative, zero, or positive, depending on whether S comes before That in the sort order, the Strings are equal, or S comes after That in the sort order, respectively.

      Before performing the comparisons, the following steps are performed to prepare the Strings:

      1. Let O be ? RequireObjectCoercible(this value).
      2. Let S be ? ToString(O).
      3. Let That be ? ToString(that).
      -

      The meaning of the optional second and third parameters to -this method are defined in the ECMA-402 specification; implementations -that do not include ECMA-402 support must not assign any other +

      The meaning of the optional second and third parameters to +this method are defined in the ECMA-402 specification; implementations +that do not include ECMA-402 support must not assign any other interpretation to those parameter positions.

      The localeCompare method, if considered as a function of two arguments this and that, is a consistent comparison function (as defined in 22.1.3.27) on the set of all Strings.

      The actual return values are implementation-defined to permit - implementers to encode additional information in the value, but the -function is required to define a total ordering on all Strings. This + implementers to encode additional information in the value, but the +function is required to define a total ordering on all Strings. This function must treat Strings that are canonically equivalent according to the Unicode standard as identical and must return 0 when comparing Strings that are considered canonically equivalent.

      Note 1

      The localeCompare method itself is not directly suitable as an argument to Array.prototype.sort because the latter requires a function of two arguments.

       Note 2
      -

      This function is intended to rely on whatever -language-sensitive comparison functionality is available to the -ECMAScript environment from the host environment, and to compare -according to the rules of the host environment's current locale. -However, regardless of the host provided comparison capabilities, this +

      This function is intended to rely on whatever +language-sensitive comparison functionality is available to the +ECMAScript environment from the host environment, and to compare +according to the rules of the host environment's current locale. +However, regardless of the host provided comparison capabilities, this function must treat Strings that are canonically equivalent according to the Unicode standard as identical. It is recommended that this function should not honour Unicode compatibility equivalences or decompositions. - For a definition and discussion of canonical equivalence see the -Unicode Standard, chapters 2 and 3, as well as Unicode Standard Annex + For a definition and discussion of canonical equivalence see the +Unicode Standard, chapters 2 and 3, as well as Unicode Standard Annex #15, Unicode Normalization Forms (https://unicode.org/reports/tr15/) and Unicode Technical Note #5, Canonical Equivalence in Applications (https://www.unicode.org/notes/tn5/). Also see Unicode Technical Standard #10, Unicode Collation Algorithm (https://unicode.org/reports/tr10/).

       Note 3
      @@ -27800,8 +27800,8 @@ Unicode Standard, chapters 2 and 3, as well as Unicode Standard Annex

      21.1.3.16.1Runtime Semantics: GetSubstitution ( matched, str, position, captures, namedCaptures, replacement )

      The abstract operation GetSubstitution performs the following steps:

      1. Assert: Type(matched) is String.
      2. Let matchLength be the number of code units in matched.
      3. Assert: Type(str) is String.
      4. Let stringLength be the number of code units in str.
      5. Assert: position is a nonnegative integer.
      6. Assert: position ≤ stringLength.
      7. Assert: captures is a possibly empty List of Strings.
      8. Assert: Type(replacement) is String.
      9. Let tailPos be position + matchLength.
      10. Let m be the number of elements in captures.
      11. If namedCaptures is not undefined, then
        1. Set namedCaptures to ? ToObject(namedCaptures).
      12. Let result be the String value derived from replacement by copying code unit elements from replacement to result while performing replacements as specified in Table 51. These $ - replacements are done left-to-right, and, once such a replacement is -performed, the new replacement text is not subject to further + replacements are done left-to-right, and, once such a replacement is +performed, the new replacement text is not subject to further replacements.
      13. Return result.
      Table 51: Replacement Text Symbol Substitutions
      @@ -27810,126 +27810,126 @@ replacements.
    49. Return result.
      50. @@ -27978,8 +27978,8 @@ replacements.
    50. Return result.

      21.1.3.19String.prototype.split ( separator, limit )

      -

      Returns an Array object into which substrings of the result -of converting this object to a String have been stored. The substrings +

      Returns an Array object into which substrings of the result +of converting this object to a String have been stored. The substrings are determined by searching from left to right for occurrences of separator; these occurrences are not part of any substring in the returned array, but serve to divide up the String value. The value of separator may be a String of any length or it may be an object, such as a RegExp, that has a @@split method.

      When the split method is called, the following steps are taken:

      1. Let O be ? RequireObjectCoercible(this value).
      2. If separator is neither undefined nor null, then
        1. Let splitter be ? GetMethod(separator, @@split).
        2. If splitter is not undefined, then
          1. Return ? Call(splitter, separator, « O, limit »).
      3. Let S be ? ToString(O).
      4. Let A be ! ArrayCreate(0).
      5. Let lengthA be 0.
      6. If limit is undefined, let lim be 232 - 1; else let lim be ? ToUint32(limit).
      7. Let s be the length of S.
      8. Let p be 0.
      9. Let R be ? ToString(separator).
      10. If lim = 0, return A.
      11. If separator is undefined, then
        1. Perform ! CreateDataProperty(A, "0", S).
        2. Return A.
      12. If s = 0, then
        1. Let z be SplitMatch(S, 0, R).
        2. If z is not false, return A.
        3. Perform ! CreateDataProperty(A, "0", S).
        4. Return A.
      13. Let q be p.
      14. Repeat, while q ≠ s
        1. Let e be SplitMatch(S, q, R).
        2. If e is false, increase q by 1.
        3. Else e is an integer index ≤ s,
          1. If e = p, increase q by 1.
          2. Else e ≠ p,
            1. Let T be the String value equal to the substring of S consisting of the code units at indices p (inclusive) through q (exclusive).
            2. Perform ! CreateDataProperty(A, ! ToString(lengthA), T).
            3. Increment lengthA by 1.
            4. If lengthA = lim, return A.
            5. Set p to e.
            6. Set q to p.
      15. Let T be the String value equal to the substring of S consisting of the code units at indices p (inclusive) through s (exclusive).
      16. Perform ! CreateDataProperty(A, ! ToString(lengthA), T).
      17. Return A. @@ -27987,13 +27987,13 @@ are determined by searching from left to right for occurrences of separator Note 1

        The value of separator may be an empty String. In this case, separator does not match the empty substring at the beginning or end of the input - String, nor does it match the empty substring at the end of the -previous separator match. If separator is the empty String, + String, nor does it match the empty substring at the end of the +previous separator match. If separator is the empty String, the String is split up into individual code unit elements; the length of - the result array equals the length of the String, and each substring + the result array equals the length of the String, and each substring contains one code unit.

        If the this object is (or converts to) the empty String, the result depends on whether separator - can match the empty String. If it can, the result array contains no + can match the empty String. If it can, the result array contains no elements. Otherwise, the result array contains one element, which is the empty String.

        If separator is undefined, then the result array contains just one String, which is the this value (converted to a String). If limit is not undefined, then the output array is truncated so that it contains no more than limit elements.

        @@ -28019,8 +28019,8 @@ elements. Otherwise, the result array contains one element, which is the

        This method returns true if the sequence of code units of searchString converted to a String is the same as the corresponding code units of this object (converted to a String) starting at index position. Otherwise returns false.

         Note 2
        -

        Throwing an exception if the first argument is a RegExp is -specified in order to allow future editions to define extensions that +

        Throwing an exception if the first argument is a RegExp is +specified in order to allow future editions to define extensions that allow such argument values.

         Note 3
        @@ -28031,8 +28031,8 @@ allow such argument values.

        21.1.3.21String.prototype.substring ( start, end )

        The substring method takes two arguments, start and end, and returns a substring of the result of converting this object to a String, starting from index start and running to, but not including, index end of the String (or through the end of the String if end is undefined). The result is a String value, not a String object.

        -

        If either argument is NaN or negative, it -is replaced with zero; if either argument is larger than the length of +

        If either argument is NaN or negative, it +is replaced with zero; if either argument is larger than the length of the String, it is replaced with the length of the String.

        If start is larger than end, they are swapped.

        The following steps are taken:

        @@ -28046,19 +28046,19 @@ the String, it is replaced with the length of the String.

        21.1.3.22String.prototype.toLocaleLowerCase ( [ reserved1 [ , reserved2 ] ] )

        An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the toLocaleLowerCase - method as specified in the ECMA-402 specification. If an ECMAScript -implementation does not include the ECMA-402 API the following + method as specified in the ECMA-402 specification. If an ECMAScript +implementation does not include the ECMA-402 API the following specification of the toLocaleLowerCase method is used.

        This function interprets a String value as a sequence of UTF-16 encoded code points, as described in 6.1.4.

        This function works exactly the same as toLowerCase - except that its result is intended to yield the correct result for the -host environment's current locale, rather than a locale-independent -result. There will only be a difference in the few cases (such as -Turkish) where the rules for that language conflict with the regular + except that its result is intended to yield the correct result for the +host environment's current locale, rather than a locale-independent +result. There will only be a difference in the few cases (such as +Turkish) where the rules for that language conflict with the regular Unicode case mappings.

        -

        The meaning of the optional parameters to this method are -defined in the ECMA-402 specification; implementations that do not -include ECMA-402 support must not use those parameter positions for +

        The meaning of the optional parameters to this method are +defined in the ECMA-402 specification; implementations that do not +include ECMA-402 support must not use those parameter positions for anything else.

        Note

        The toLocaleLowerCase function is intentionally generic; it does not require that its this value be a String object. Therefore, it can be transferred to other kinds of objects for use as a method.

        @@ -28068,19 +28068,19 @@ anything else.

        21.1.3.23String.prototype.toLocaleUpperCase ( [ reserved1 [ , reserved2 ] ] )

        An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the toLocaleUpperCase - method as specified in the ECMA-402 specification. If an ECMAScript -implementation does not include the ECMA-402 API the following + method as specified in the ECMA-402 specification. If an ECMAScript +implementation does not include the ECMA-402 API the following specification of the toLocaleUpperCase method is used.

        This function interprets a String value as a sequence of UTF-16 encoded code points, as described in 6.1.4.

        This function works exactly the same as toUpperCase - except that its result is intended to yield the correct result for the -host environment's current locale, rather than a locale-independent -result. There will only be a difference in the few cases (such as -Turkish) where the rules for that language conflict with the regular + except that its result is intended to yield the correct result for the +host environment's current locale, rather than a locale-independent +result. There will only be a difference in the few cases (such as +Turkish) where the rules for that language conflict with the regular Unicode case mappings.

        -

        The meaning of the optional parameters to this method are -defined in the ECMA-402 specification; implementations that do not -include ECMA-402 support must not use those parameter positions for +

        The meaning of the optional parameters to this method are +defined in the ECMA-402 specification; implementations that do not +include ECMA-402 support must not use those parameter positions for anything else.

        Note

        The toLocaleUpperCase function is intentionally generic; it does not require that its this value be a String object. Therefore, it can be transferred to other kinds of objects for use as a method.

        @@ -28092,14 +28092,14 @@ anything else.

        This function interprets a String value as a sequence of UTF-16 encoded code points, as described in 6.1.4. The following steps are taken:

        1. Let O be ? RequireObjectCoercible(this value).
        2. Let S be ? ToString(O).
        3. Let cpList be a List containing in order the code points as defined in 6.1.4 of S, starting at the first element of S.
        4. Let cuList be a List where the elements are the result of toLowercase(cpList), according to the Unicode Default Case Conversion algorithm.
        5. Let L be the String value whose code units are the UTF16Encoding of the code points of cuList.
        6. Return L.
        -

        The result must be derived according to the +

        The result must be derived according to the locale-insensitive case mappings in the Unicode Character Database (this - explicitly includes not only the UnicodeData.txt file, but also all -locale-insensitive mappings in the SpecialCasings.txt file that + explicitly includes not only the UnicodeData.txt file, but also all +locale-insensitive mappings in the SpecialCasings.txt file that accompanies it).

        Note 1
        -

        The case mapping of some code points may produce multiple -code points. In this case the result String may not be the same length +

        The case mapping of some code points may produce multiple +code points. In this case the result String may not be the same length as the source String. Because both toUpperCase and toLowerCase have context-sensitive behaviour, the functions are not symmetrical. In other words, s.toUpperCase().toLowerCase() is not necessarily equal to s.toLowerCase().

         Note 2
        @@ -28142,8 +28142,8 @@ as the source String. Because both toUpperCase and toLowerCas
        1. Let str be ? RequireObjectCoercible(string).
        2. Let S be ? ToString(str).
        3. If where is "start", let T be the String value that is a copy of S with leading white space removed.
        4. Else if where is "end", let T be the String value that is a copy of S with trailing white space removed.
        5. Else,
          1. Assert: where is "start+end".
          2. Let T be the String value that is a copy of S with both leading and trailing white space removed.
        6. Return T.

        The definition of white space is the union of WhiteSpace and LineTerminator. - When determining whether a Unicode code point is in Unicode general -category “Space_Separator” (“Zs”), code unit sequences are interpreted + When determining whether a Unicode code point is in Unicode general +category “Space_Separator” (“Zs”), code unit sequences are interpreted as UTF-16 encoded code point sequences as specified in 6.1.4.

        @@ -28180,7 +28180,7 @@ as UTF-16 encoded code point sequences as specified in

        21.1.3.31String.prototype [ @@iterator ] ( )

        When the @@iterator method is called it returns an Iterator object (25.1.1.2) - that iterates over the code points of a String value, returning each + that iterates over the code points of a String value, returning each code point as a String value. The following steps are taken:

        1. Let O be ? RequireObjectCoercible(this value).
        2. Let S be ? ToString(O).
        3. Return CreateStringIterator(S).
        @@ -28190,8 +28190,8 @@ code point as a String value. The following steps are taken:

        21.1.4Properties of String Instances

        -

        String instances are String exotic objects and have the -internal methods specified for such objects. String instances inherit +

        String instances are String exotic objects and have the +internal methods specified for such objects. String instances inherit properties from the String prototype object. String instances also have a [[StringData]] internal slot.

        String instances have a "length" property, and a set of enumerable properties with integer-indexed names.

        @@ -28205,10 +28205,10 @@ properties from the String prototype object. String instances also have a

        21.1.5String Iterator Objects

        -

        A String Iterator is an object, that represents a specific -iteration over some specific String instance object. There is not a +

        A String Iterator is an object, that represents a specific +iteration over some specific String instance object. There is not a named constructor - for String Iterator objects. Instead, String iterator objects are + for String Iterator objects. Instead, String iterator objects are created by calling certain methods of String instance objects.

        @@ -28250,31 +28250,31 @@ created by calling certain methods of String instance objects.

      51.  @@ -28288,15 +28288,15 @@ created by calling certain methods of String instance objects.

      21.2RegExp (Regular Expression) Objects

      A RegExp object contains a regular expression and the associated flags.

      Note
      -

      The form and functionality of regular expressions is modelled -after the regular expression facility in the Perl 5 programming +

      The form and functionality of regular expressions is modelled +after the regular expression facility in the Perl 5 programming language.

      21.2.1Patterns

      The RegExp constructor - applies the following grammar to the input pattern String. An error + applies the following grammar to the input pattern String. An error occurs if the grammar cannot interpret the String as an expansion of Pattern.

      Syntax

      @@ -28508,11 +28508,11 @@ occurs if the grammar cannot interpret the String as an expansion of
    51. It is a Syntax Error if NcapturingParens ≥ 232 - 1. - +
    52. It is a Syntax Error if Pattern contains multiple GroupSpecifiers whose enclosed RegExpIdentifierNames have the same StringValue. - +
      53. @@ -28521,7 +28521,7 @@ occurs if the grammar cannot interpret the String as an expansion of
    53. It is a Syntax Error if the MV of the first DecimalDigits is larger than the MV of the second DecimalDigits. - +
      54. @@ -28530,7 +28530,7 @@ occurs if the grammar cannot interpret the String as an expansion of
    54. It is a Syntax Error if the enclosing Pattern does not contain a GroupSpecifier with an enclosed RegExpIdentifierName whose StringValue equals the StringValue of the RegExpIdentifierName of this production's GroupName. - +
      55. @@ -28539,7 +28539,7 @@ occurs if the grammar cannot interpret the String as an expansion of
    55. It is a Syntax Error if the CapturingGroupNumber of DecimalEscape is larger than NcapturingParens (21.2.2.1). - +
      56. @@ -28548,11 +28548,11 @@ occurs if the grammar cannot interpret the String as an expansion of
    56. It is a Syntax Error if IsCharacterClass of the first ClassAtom is true or IsCharacterClass of the second ClassAtom is true. - +
    57. It is a Syntax Error if IsCharacterClass of the first ClassAtom is false and IsCharacterClass of the second ClassAtom is false and the CharacterValue of the first ClassAtom is larger than the CharacterValue of the second ClassAtom. - +
      58. @@ -28561,11 +28561,11 @@ occurs if the grammar cannot interpret the String as an expansion of
    58. It is a Syntax Error if IsCharacterClass of ClassAtomNoDash is true or IsCharacterClass of ClassAtom is true. - +
    59. It is a Syntax Error if IsCharacterClass of ClassAtomNoDash is false and IsCharacterClass of ClassAtom is false and the CharacterValue of ClassAtomNoDash is larger than the CharacterValue of ClassAtom. - +
      60. @@ -28574,7 +28574,7 @@ occurs if the grammar cannot interpret the String as an expansion of
    60. It is a Syntax Error if SV(RegExpUnicodeEscapeSequence) is none of "$", or "_", or the UTF16Encoding of a code point matched by the UnicodeIDStart lexical grammar production. - +
      61. @@ -28583,7 +28583,7 @@ occurs if the grammar cannot interpret the String as an expansion of
    61. It is a Syntax Error if SV(RegExpUnicodeEscapeSequence) is none of "$", or "_", or the UTF16Encoding of either <ZWNJ> or <ZWJ>, or the UTF16Encoding of a Unicode code point that would be matched by the UnicodeIDContinue lexical grammar production. - +
      62. @@ -28592,11 +28592,11 @@ occurs if the grammar cannot interpret the String as an expansion of
    62. It is a Syntax Error if the List of Unicode code points that is SourceText of UnicodePropertyName is not identical to a List of Unicode code points that is a Unicode property name or property alias listed in the “Property name and aliases” column of Table 54. - +
    63. It is a Syntax Error if the List of Unicode code points that is SourceText of UnicodePropertyValue is not identical to a List of Unicode code points that is a value or value alias for the Unicode property or property alias given by SourceText of UnicodePropertyName listed in the “Property value and aliases” column of the corresponding tables Table 56 or Table 57. - +
      64. @@ -28605,9 +28605,9 @@ occurs if the grammar cannot interpret the String as an expansion of
    64. It is a Syntax Error if the List of Unicode code points that is SourceText of LoneUnicodePropertyNameOrValue is not identical to a List - of Unicode code points that is a Unicode general category or general + of Unicode code points that is a Unicode general category or general category alias listed in the “Property value and aliases” column of Table 56, nor a binary property or binary property alias listed in the “Property name and aliases” column of Table 55. - +
      65. @@ -28686,133 +28686,133 @@ category alias listed in the “Property value and aliases” column of       @@ -28910,39 +28910,39 @@ category alias listed in the “Property value and aliases” column of

      21.2.2Pattern Semantics

      -

      A regular expression pattern is converted into an internal -procedure using the process described below. An implementation is -encouraged to use more efficient algorithms than the ones listed below, -as long as the results are the same. The internal procedure is used as +

      A regular expression pattern is converted into an internal +procedure using the process described below. An implementation is +encouraged to use more efficient algorithms than the ones listed below, +as long as the results are the same. The internal procedure is used as the value of a RegExp object's [[RegExpMatcher]] internal slot.

      A Pattern is either a BMP pattern or a Unicode pattern depending upon whether or not its associated flags contain a "u". - A BMP pattern matches against a String interpreted as consisting of a -sequence of 16-bit values that are Unicode code points in the range of + A BMP pattern matches against a String interpreted as consisting of a +sequence of 16-bit values that are Unicode code points in the range of the Basic Multilingual Plane. A Unicode pattern matches against a String - interpreted as consisting of Unicode code points encoded using UTF-16. -In the context of describing the behaviour of a BMP pattern “character” -means a single 16-bit Unicode BMP code point. In the context of + interpreted as consisting of Unicode code points encoded using UTF-16. +In the context of describing the behaviour of a BMP pattern “character” +means a single 16-bit Unicode BMP code point. In the context of describing the behaviour of a Unicode pattern “character” means a UTF-16 encoded code point (6.1.4). In either context, “character value” means the numeric value of the corresponding non-encoded code point.

      The syntax and semantics of Pattern is defined as if the source code for the Pattern was a List of SourceCharacter values where each SourceCharacter corresponds to a Unicode code point. If a BMP pattern contains a non-BMP SourceCharacter the entire pattern is encoded using UTF-16 and the individual code units of that encoding are used as the elements of the List.

      Note
      -

      For example, consider a pattern expressed in source text as -the single non-BMP character U+1D11E (MUSICAL SYMBOL G CLEF). -Interpreted as a Unicode pattern, it would be a single element +

      For example, consider a pattern expressed in source text as +the single non-BMP character U+1D11E (MUSICAL SYMBOL G CLEF). +Interpreted as a Unicode pattern, it would be a single element (character) List - consisting of the single code point 0x1D11E. However, interpreted as a + consisting of the single code point 0x1D11E. However, interpreted as a BMP pattern, it is first UTF-16 encoded to produce a two element List consisting of the code units 0xD834 and 0xDD1E.

      Patterns are passed to the RegExp constructor - as ECMAScript String values in which non-BMP characters are UTF-16 -encoded. For example, the single character MUSICAL SYMBOL G CLEF -pattern, expressed as a String value, is a String of length 2 whose -elements were the code units 0xD834 and 0xDD1E. So no further -translation of the string would be necessary to process it as a BMP + as ECMAScript String values in which non-BMP characters are UTF-16 +encoded. For example, the single character MUSICAL SYMBOL G CLEF +pattern, expressed as a String value, is a String of length 2 whose +elements were the code units 0xD834 and 0xDD1E. So no further +translation of the string would be necessary to process it as a BMP pattern consisting of two pattern characters. However, to process it as a Unicode pattern UTF16Decode must be used in producing a List consisting of a single pattern character, the code point U+1D11E.

      -

      An implementation may not actually perform such translations +

      An implementation may not actually perform such translations to or from UTF-16, but the semantics of this specification requires that - the result of pattern matching be as if such translations were + the result of pattern matching be as if such translations were performed.

       @@ -28952,15 +28952,15 @@ performed.

      • Input is a List - consisting of all of the characters, in order, of the String being -matched by the regular expression pattern. Each character is either a -code unit or a code point, depending upon the kind of pattern involved. + consisting of all of the characters, in order, of the String being +matched by the regular expression pattern. Each character is either a +code unit or a code point, depending upon the kind of pattern involved. The notation Input[n] means the nth character of Input, where n can range between 0 (inclusive) and InputLength (exclusive). - +
      • InputLength is the number of characters in Input. - +
      • NcapturingParens is the total number of left-capturing parentheses (i.e. the total number of @@ -28968,78 +28968,78 @@ The notation Input[n] means the nth Parse Nodes) in the pattern. A left-capturing parenthesis is any ( pattern character that is matched by the ( terminal of the Atom::(GroupSpecifierDisjunction) production. - +
      • DotAll is true if the RegExp object's [[OriginalFlags]] internal slot contains "s" and otherwise is false. - +
      • IgnoreCase is true if the RegExp object's [[OriginalFlags]] internal slot contains "i" and otherwise is false. - +
      • Multiline is true if the RegExp object's [[OriginalFlags]] internal slot contains "m" and otherwise is false. - +
      • Unicode is true if the RegExp object's [[OriginalFlags]] internal slot contains "u" and otherwise is false. - +

      Furthermore, the descriptions below use the following internal data structures:

      • A CharSet is a mathematical set of characters, either code units or code points depending up the state of the Unicode flag. “All characters” means either all code unit values or all code point values also depending upon the state of Unicode. - +
      • A State is an ordered pair (endIndex, captures) where endIndex is an integer and captures is a List of NcapturingParens values. States are used to represent partial match states in the regular expression matching algorithms. The endIndex is one plus the index of the last input character matched so far by the pattern, while captures holds the results of capturing parentheses. The nth element of captures is either a List that represents the value obtained by the nth set of capturing parentheses or undefined if the nth - set of capturing parentheses hasn't been reached yet. Due to -backtracking, many States may be in use at any time during the matching + set of capturing parentheses hasn't been reached yet. Due to +backtracking, many States may be in use at any time during the matching process. - +
      • A MatchResult is either a State or the special token failure that indicates that the match failed. - +
      • - A Continuation procedure is an internal closure + A Continuation procedure is an internal closure (i.e. an internal procedure with some arguments already bound to values) - that takes one State argument and returns a MatchResult result. If an -internal closure references variables which are bound in the function -that creates the closure, the closure uses the values that these -variables had at the time the closure was created. The Continuation -attempts to match the remaining portion (specified by the closure's -already-bound arguments) of the pattern against Input, -starting at the intermediate state given by its State argument. If the -match succeeds, the Continuation returns the final State that it + that takes one State argument and returns a MatchResult result. If an +internal closure references variables which are bound in the function +that creates the closure, the closure uses the values that these +variables had at the time the closure was created. The Continuation +attempts to match the remaining portion (specified by the closure's +already-bound arguments) of the pattern against Input, +starting at the intermediate state given by its State argument. If the +match succeeds, the Continuation returns the final State that it reached; if the match fails, the Continuation returns failure. - +
      • - A Matcher procedure is an internal closure that -takes two arguments — a State and a Continuation — and returns a -MatchResult result. A Matcher attempts to match a middle subpattern -(specified by the closure's already-bound arguments) of the pattern -against Input, starting at the intermediate state given by -its State argument. The Continuation argument should be a closure that -matches the rest of the pattern. After matching the subpattern of a -pattern to obtain a new State, the Matcher then calls Continuation on -that new State to test if the rest of the pattern can match as well. If -it can, the Matcher returns the State returned by Continuation; if not, -the Matcher may try different choices at its choice points, repeatedly -calling Continuation until it either succeeds or all possibilities have + A Matcher procedure is an internal closure that +takes two arguments — a State and a Continuation — and returns a +MatchResult result. A Matcher attempts to match a middle subpattern +(specified by the closure's already-bound arguments) of the pattern +against Input, starting at the intermediate state given by +its State argument. The Continuation argument should be a closure that +matches the rest of the pattern. After matching the subpattern of a +pattern to obtain a new State, the Matcher then calls Continuation on +that new State to test if the rest of the pattern can match as well. If +it can, the Matcher returns the State returned by Continuation; if not, +the Matcher may try different choices at its choice points, repeatedly +calling Continuation until it either succeeds or all possibilities have been exhausted. - +
      • - An AssertionTester procedure is an internal -closure that takes a State argument and returns a Boolean result. The -assertion tester tests a specific condition (specified by the closure's + An AssertionTester procedure is an internal +closure that takes a State argument and returns a Boolean result. The +assertion tester tests a specific condition (specified by the closure's already-bound arguments) against the current place in Input and returns true if the condition matched or false if not. - +
      @@ -29053,13 +29053,13 @@ already-bound arguments) against the current place in Input and retur Note

      A Pattern evaluates (“compiles”) to an internal procedure value. RegExpBuiltinExec - can then apply this procedure to a String and an offset within the -String to determine whether the pattern would match starting at exactly + can then apply this procedure to a String and an offset within the +String to determine whether the pattern would match starting at exactly that offset within the String, and, if it does match, what the values of the capturing parentheses would be. The algorithms in 21.2.2 are designed so that compiling a pattern may throw a SyntaxError - exception; on the other hand, once the pattern is successfully + exception; on the other hand, once the pattern is successfully compiled, applying the resulting internal procedure to find a match in a - String cannot throw an exception (except for any host-defined + String cannot throw an exception (except for any host-defined exceptions that can occur anywhere such as out-of-memory).

       @@ -29105,8 +29105,8 @@ exceptions that can occur anywhere such as out-of-memory).

      Note

      Consecutive Terms try to simultaneously match consecutive portions of Input. When direction is equal to +1, if the left Alternative, the right Term, - and the sequel of the regular expression all have choice points, all -choices in the sequel are tried before moving on to the next choice in + and the sequel of the regular expression all have choice points, all +choices in the sequel are tried before moving on to the next choice in the right Term, and all choices in the right Term are tried before moving on to the next choice in the left Alternative. When direction is equal to -1, the evaluation order of Alternative and Term are reversed.

       @@ -29147,11 +29147,11 @@ the right Term, and al Note 2

      If the Atom and the sequel of the regular expression all have choice points, the Atom - is first matched as many (or as few, if non-greedy) times as possible. -All choices in the sequel are tried before moving on to the next choice + is first matched as many (or as few, if non-greedy) times as possible. +All choices in the sequel are tried before moving on to the next choice in the last repetition of Atom. All choices in the last (nth) repetition of Atom are tried before moving on to the next choice in the next-to-last (n - 1)st repetition of Atom; at which point it may turn out that more or fewer repetitions of Atom - are now possible; these are exhausted (again, starting with either as -few or as many as possible) before moving on to the next choice in the + are now possible; these are exhausted (again, starting with either as +few or as many as possible) before moving on to the next choice in the (n - 1)st repetition of Atom and so on.

      Compare

      /a[a-z]{2,4}/.exec("abcdefghi")
      @@ -29166,8 +29166,8 @@ few or as many as possible) before moving on to the next choice in the 
      ["aabaac", "aabaac"]
 ["aabaac", "c"]

      The above ordering of choice points can be used to write a - regular expression that calculates the greatest common divisor of two -numbers (represented in unary notation). The following example + regular expression that calculates the greatest common divisor of two +numbers (represented in unary notation). The following example calculates the gcd of 10 and 15:

      "aaaaaaaaaa,aaaaaaaaaaaaaaa".replace(/^(a+)\1*,\1+$/, "$1")

      which returns the gcd in unary notation "aaaaa".

      @@ -29183,8 +29183,8 @@ calculates the gcd of 10 and 15:

       Note 4

      Step 1 of the RepeatMatcher's d closure states that, once the minimum number of repetitions has been satisfied, any more expansions of Atom - that match the empty character sequence are not considered for further -repetitions. This prevents the regular expression engine from falling + that match the empty character sequence are not considered for further +repetitions. This prevents the regular expression engine from falling into an infinite loop on patterns such as:

      /(a*)*/.exec("b")

      or the slightly more complicated:

      @@ -29579,15 +29579,15 @@ into an infinite loop on patterns such as:

      Note 1

      Parentheses of the form ( Disjunction ) serve both to group the components of the Disjunction pattern together and to save the result of the match. The result can be used either in a backreference (\ - followed by a nonzero decimal number), referenced in a replace String, -or returned as part of an array from the regular expression matching -internal procedure. To inhibit the capturing behaviour of parentheses, + followed by a nonzero decimal number), referenced in a replace String, +or returned as part of an array from the regular expression matching +internal procedure. To inhibit the capturing behaviour of parentheses, use the form (?: Disjunction ) instead.

       Note 2

      The form (?= Disjunction ) specifies a zero-width positive lookahead. In order for it to succeed, the pattern inside Disjunction must match at the current position, but the current position is not advanced before matching the sequel. If Disjunction - can match at the current position in several ways, only the first one -is tried. Unlike other regular expression operators, there is no + can match at the current position in several ways, only the first one +is tried. Unlike other regular expression operators, there is no backtracking into a (?= form (this unusual behaviour is inherited from Perl). This only matters when the Disjunction contains capturing parentheses and the sequel of the pattern contains backreferences to those captures.

      For example,

      /(?=(a+))/.exec("baaabac")
      @@ -29608,9 +29608,9 @@ backtracking into a (?= form (this unusual behaviour is inherited f
      Note 4

      In case-insignificant matches when Unicode is true, - all characters are implicitly case-folded using the simple mapping -provided by the Unicode standard immediately before they are compared. -The simple mapping always maps to a single code point, so it does not + all characters are implicitly case-folded using the simple mapping +provided by the Unicode standard immediately before they are compared. +The simple mapping always maps to a single code point, so it does not map, for example, "ß" (U+00DF) to "SS". It may however map a code point outside the Basic Latin range to a character within, for example, "ſ" (U+017F) to "s". Such characters are not mapped if Unicode is false. This prevents Unicode code points such as U+017F and U+212A from matching regular expressions such as /[a-z]/i, but they will match /[a-z]/ui.

       @@ -29627,7 +29627,7 @@ map, for example, "ß" (U+00DF) to "SS". It may howeve

      The listed properties form a superset of what UTS18 RL1.2 requires.
      Table 54: Non-binary Unicode property aliases and their canonical property names
      - +
      Field Name - + Value - + Usage - +
      [[Key]] - + A String - + A string key used to globally identify a Symbol. - +
      [[Symbol]] - + A Symbol - + A symbol that can be retrieved from any realm. - +
      YYYY - + is the decimal digits of the year 0000 to 9999 in the proleptic Gregorian calendar. - +
      - - + "-" (hyphen) appears literally twice in the string. - +
      MM - + is the month of the year from 01 (January) to 12 (December). - +
      DD - + is the day of the month from 01 to 31. - +
      T - + "T" appears literally in the string, to indicate the beginning of the time element. - +
      HH - + is the number of complete hours that have passed since midnight as two decimal digits from 00 to 24. - +
      : - + ":" (colon) appears literally twice in the string. - +
      mm - + is the number of complete minutes since the start of the hour as two decimal digits from 00 to 59. - +
      ss - + is the number of complete seconds since the start of the minute as two decimal digits from 00 to 59. - +
      . - + "." (dot) appears literally in the string. - +
      sss - + is the number of complete milliseconds since the start of the second as three decimal digits. - +
      Z - + is the time zone offset specified as "Z" (for UTC) or either "+" or "-" followed by a time expression HH:mm - +
      Number - + Name - +
      0 - + "Sun" - +
      1 - + "Mon" - +
      2 - + "Tue" - +
      3 - + "Wed" - +
      4 - + "Thu" - +
      5 - + "Fri" - +
      6 - + "Sat" - +
      Number - + Name - +
      0 - + "Jan" - +
      1 - + "Feb" - +
      2 - + "Mar" - +
      3 - + "Apr" - +
      4 - + "May" - +
      5 - + "Jun" - +
      6 - + "Jul" - +
      7 - + "Aug" - +
      8 - + "Sep" - +
      9 - + "Oct" - +
      10 - + "Nov" - +
      11 - + "Dec" - +
      Code units - + Unicode Characters - + Replacement text - +
      0x0024, 0x0024 - + $$ - + $ - +
      0x0024, 0x0026 - + $& - + matched - +
      0x0024, 0x0060 - + $` If position is 0, the replacement is the empty String. Otherwise the replacement is the substring of str that starts at index 0 and whose last code unit is at index position - 1. - +
      0x0024, 0x0027 - + $' - + If tailPos ≥ stringLength, the replacement is the empty String. Otherwise the replacement is the substring of str that starts at index tailPos and continues to the end of str. - +
      0x0024, N - +
      Where - +
      0x0031 ≤ N ≤ 0x0039 - +       		$n where - +
      n is one of 1 2 3 4 5 6 7 8 9 and $n is not followed by a decimal digit - +       		The nth element of captures, where n is a single digit in the range 1 to 9. If n ≤ m and the nth element of captures is undefined, use the empty String instead. If n > m, no replacement is done. - +
      0x0024, N, N - +
      Where - +
      0x0030 ≤ N ≤ 0x0039 - +       		$nn where - +
      n is one of 0 1 2 3 4 5 6 7 8 9 - +       		The nnth element of captures, where nn is a two-digit decimal number in the range 01 to 99. If nn ≤ m and the nnth element of captures is undefined, use the empty String instead. If nn is 00 or nn > m, no replacement is done. - +
      0x0024, 0x003C - + $< - +
      1. If namedCaptures is undefined, the replacement text is the String "$<".
      2. Else,
        1. Scan until the next > U+003E (GREATER-THAN SIGN).
        2. If none is found, the replacement text is the String "$<".
        3. Else,
          1. Let groupName be the enclosed substring.
          2. Let capture be ? Get(namedCaptures, groupName).
          3. If capture is undefined, replace the text through > with the empty string.
          4. Otherwise, replace the text through > with ? ToString(capture). @@ -27939,15 +27939,15 @@ replacements.
          5. Return result.
      0x0024 - + $ in any context that does not match any of the above. - + $ - +
      Internal Slot - + Description - +
      [[IteratedString]] - + The String value whose code units are being iterated. - +
      [[StringIteratorNextIndex]] - + The integer index of the next string index to be examined by this iteration. - +
      ControlEscape - + Code Point Value - + Code Point - + Unicode Name - + Symbol - +
      t - + 9 - + U+0009 - + CHARACTER TABULATION - + <HT> - +
      n - + 10 - + U+000A - + LINE FEED (LF) - + <LF> - +
      v - + 11 - + U+000B - + LINE TABULATION - + <VT> - +
      f - + 12 - + U+000C - + FORM FEED (FF) - + <FF> - +
      r - + 13 - + U+000D - + CARRIAGE RETURN (CR) - + <CR> - +
      @@ -29666,7 +29666,7 @@ map, for example, "ß" (U+00DF) to "SS". It may howeve
      Table 55: Binary Unicode property aliases and their canonical property names
      - +
      @@ -30103,7 +30103,7 @@ map, for example, "ß" (U+00DF) to "SS". It may howeve

      This algorithm differs from the matching rules for symbolic values listed in UAX44: case, white space, U+002D (HYPHEN-MINUS), and U+005F (LOW LINE) are not ignored, and the Is prefix is not supported.

      Table 56: Value aliases and canonical values for the Unicode property General_Category
      - +
      @@ -30461,7 +30461,7 @@ map, for example, "ß" (U+00DF) to "SS". It may howeve
      Table 57: Value aliases and canonical values for the Unicode properties Script and Script_Extensions
      - +
      @@ -31927,8 +31927,8 @@ map, for example, "ß" (U+00DF) to "SS". It may howeve UnicodePropertyValueExpression::LoneUnicodePropertyNameOrValue evaluates as follows:

      1. Let s be SourceText of LoneUnicodePropertyNameOrValue.
      2. If ! UnicodeMatchPropertyValue("General_Category", s) is identical to a List - of Unicode code points that is the name of a Unicode general category -or general category alias listed in the “Property value and aliases” + of Unicode code points that is the name of a Unicode general category +or general category alias listed in the “Property value and aliases” column of Table 56, then
        1. Return the CharSet containing all Unicode code points whose character database definition includes the property “General_Category” with value s.
      3. Let p be ! UnicodeMatchProperty(s).
      4. Assert: p is a binary Unicode property or binary property alias listed in the “Property name and aliases” column of Table 55.
      5. Return the CharSet containing all Unicode code points whose character database definition includes the property p with value “True”. @@ -32010,8 +32010,8 @@ column of

        ClassRanges can expand into a single ClassAtom and/or ranges of two ClassAtom separated by dashes. In the latter case the ClassRanges includes all characters between the first ClassAtom and the second ClassAtom, inclusive; an error occurs if either ClassAtom does not represent a single character (for example, if one is \w) or if the first ClassAtom's character value is greater than the second ClassAtom's character value.

        Note 2
        -

        Even if the pattern ignores case, the case of the two ends -of a range is significant in determining which characters belong to the +

        Even if the pattern ignores case, the case of the two ends +of a range is significant in determining which characters belong to the range. Thus, for example, the pattern /[E-F]/i matches only the letters E, F, e, and f, while the pattern /[E-f]/i matches all upper and lower-case letters in the Unicode Basic Latin block as well as the symbols [, \, ], ^, _, and `.

         Note 3
        @@ -32090,8 +32090,8 @@ range. Thus, for example, the pattern /[E-F]/i matches only the let Note

        If pattern is supplied using a StringLiteral, the usual escape sequence substitutions are performed before the String - is processed by RegExp. If pattern must contain an escape sequence to -be recognized by RegExp, any U+005C (REVERSE SOLIDUS) code points must + is processed by RegExp. If pattern must contain an escape sequence to +be recognized by RegExp, any U+005C (REVERSE SOLIDUS) code points must be escaped within the StringLiteral to prevent them being removed when the contents of the StringLiteral are formed.

         @@ -32124,8 +32124,8 @@ be escaped within the Stri

        21.2.3.2.4Runtime Semantics: EscapeRegExpPattern ( P, F )

        When the abstract operation EscapeRegExpPattern with arguments P and F is called, the following occurs:

        1. Let S be a String in the form of a Pattern[~U] (Pattern[+U] if F contains "u") equivalent to P interpreted as UTF-16 encoded Unicode code points (6.1.4), in which certain code points are escaped as described below. S may or may not be identical to P; however, the internal procedure that would result from evaluating S as a Pattern[~U] (Pattern[+U] if F contains "u") - must behave identically to the internal procedure given by the -constructed object's [[RegExpMatcher]] internal slot. Multiple calls to + must behave identically to the internal procedure given by the +constructed object's [[RegExpMatcher]] internal slot. Multiple calls to this abstract operation using the same values for P and F must produce identical results.
        2. The code points / or any LineTerminator occurring in the pattern shall be escaped in S as necessary to ensure that the string-concatenation of "/", S, "/", and F can be parsed (in an appropriate lexical context) as a RegularExpressionLiteral that behaves identically to the constructed regular expression. For example, if P is "/", then S could be "\/" or "\u002F", among other possibilities, but not "/", because /// followed by F would be parsed as a SingleLineComment rather than a RegularExpressionLiteral. If P is the empty String, this specification can be met by letting S be "(?:)".
        3. Return S.
        @@ -32164,8 +32164,8 @@ this abstract operation using the same values for P and F
        • is the intrinsic object %RegExpPrototype%.
        • is an ordinary object.
          • -
        • is not a RegExp instance and does not have a -[[RegExpMatcher]] internal slot or any of the other internal slots of +
        • is not a RegExp instance and does not have a +[[RegExpMatcher]] internal slot or any of the other internal slots of RegExp instance objects.
        • has a [[Prototype]] internal slot whose value is the intrinsic object %ObjectPrototype%.
        @@ -32191,10 +32191,10 @@ RegExp instance objects.
        1. Assert: Type(R) is Object.
        2. Assert: Type(S) is String.
        3. Let exec be ? Get(R, "exec").
        4. If IsCallable(exec) is true, then
          1. Let result be ? Call(exec, R, « S »).
          2. If Type(result) is neither Object or Null, throw a TypeError exception.
          3. Return result.
        5. If R does not have a [[RegExpMatcher]] internal slot, throw a TypeError exception.
        6. Return ? RegExpBuiltinExec(R, S).
        Note
        -

        If a callable exec property is not found -this algorithm falls back to attempting to use the built-in RegExp -matching algorithm. This provides compatible behaviour for code written -for prior editions where most built-in algorithms that use regular +

        If a callable exec property is not found +this algorithm falls back to attempting to use the built-in RegExp +matching algorithm. This provides compatible behaviour for code written +for prior editions where most built-in algorithms that use regular expressions did not perform a dynamic property lookup of exec.

         @@ -32267,8 +32267,8 @@ expressions did not perform a dynamic property lookup of exec.

        21.2.5.9RegExp.prototype [ @@replace ] ( string, replaceValue )

        When the @@replace method is called with arguments string and replaceValue, the following steps are taken:

        1. Let rx be the this value.
        2. If Type(rx) is not Object, throw a TypeError exception.
        3. Let S be ? ToString(string).
        4. Let lengthS be the number of code unit elements in S.
        5. Let functionalReplace be IsCallable(replaceValue).
        6. If functionalReplace is false, then
          1. Set replaceValue to ? ToString(replaceValue).
        7. Let global be ToBoolean(? Get(rx, "global")).
        8. If global is true, then
          1. Let fullUnicode be ToBoolean(? Get(rx, "unicode")).
          2. Perform ? Set(rx, "lastIndex", 0, true).
        9. Let results be a new empty List.
        10. Let done be false.
        11. Repeat, while done is false
          1. Let result be ? RegExpExec(rx, S).
          2. If result is null, set done to true.
          3. Else result is not null,
            1. Append result to the end of results.
            2. If global is false, set done to true.
            3. Else,
              1. Let matchStr be ? ToString(? Get(result, "0")).
              2. If matchStr is the empty String, then
                1. Let thisIndex be ? ToLength(? Get(rx, "lastIndex")).
                2. Let nextIndex be AdvanceStringIndex(S, thisIndex, fullUnicode).
                3. Perform ? Set(rx, "lastIndex", nextIndex, true).
        12. Let accumulatedResult be the empty String value.
        13. Let nextSourcePosition be 0.
        14. For each result in results, do
          1. Let nCaptures be ? ToLength(? Get(result, "length")).
          2. Set nCaptures to max(nCaptures - 1, 0).
          3. Let matched be ? ToString(? Get(result, "0")).
          4. Let matchLength be the number of code units in matched.
          5. Let position be ? ToInteger(? Get(result, "index")).
          6. Set position to max(min(position, lengthS), 0).
          7. Let n be 1.
          8. Let captures be a new empty List.
          9. Repeat, while n ≤ nCaptures
            1. Let capN be ? Get(result, ! ToString(n)).
            2. If capN is not undefined, then
              1. Set capN to ? ToString(capN).
            3. Append capN as the last element of captures.
            4. Increase n by 1.
          10. Let namedCaptures be ? Get(result, "groups").
          11. If functionalReplace is true, then
            1. Let replacerArgs be « matched ».
            2. Append in list order the elements of captures to the end of the List replacerArgs.
            3. Append position and S to replacerArgs.
            4. If namedCaptures is not undefined, then
              1. Append namedCaptures as the last element of replacerArgs.
            5. Let replValue be ? Call(replaceValue, undefined, replacerArgs).
            6. Let replacement be ? ToString(replValue).
          12. Else,
            1. Let replacement be GetSubstitution(matched, S, position, captures, namedCaptures, replaceValue).
          13. If position ≥ nextSourcePosition, then
            1. NOTE: position - should not normally move backwards. If it does, it is an indication of -an ill-behaving RegExp subclass or use of an access triggered + should not normally move backwards. If it does, it is an indication of +an ill-behaving RegExp subclass or use of an access triggered side-effect to change the global flag or other characteristics of rx. In such cases, the corresponding substitution is ignored.
            2. Set accumulatedResult to the string-concatenation of the current value of accumulatedResult, the substring of S consisting of the code units from nextSourcePosition (inclusive) up to position (exclusive), and replacement.
            3. Set nextSourcePosition to position + matchLength.
        15. If nextSourcePosition ≥ lengthS, return accumulatedResult.
        16. Return the string-concatenation of accumulatedResult and the substring of S consisting of the code units from nextSourcePosition (inclusive) up through the final code unit of S (inclusive).

        The value of the name property of this function is "[Symbol.replace]".

        @@ -32296,24 +32296,24 @@ side-effect to change the global flag or other characteristics of rx.

        21.2.5.12RegExp.prototype [ @@split ] ( string, limit )

        Note 1

        Returns an Array object into which substrings of the result of converting string to a String have been stored. The substrings are determined by searching from left to right for matches of the this - value regular expression; these occurrences are not part of any -substring in the returned array, but serve to divide up the String + value regular expression; these occurrences are not part of any +substring in the returned array, but serve to divide up the String value.

        -

        The this value may be an empty regular -expression or a regular expression that can match an empty String. In -this case, the regular expression does not match the empty substring at -the beginning or end of the input String, nor does it match the empty -substring at the end of the previous separator match. (For example, if -the regular expression matches the empty String, the String is split up -into individual code unit elements; the length of the result array -equals the length of the String, and each substring contains one code -unit.) Only the first match at a given index of the String is +

        The this value may be an empty regular +expression or a regular expression that can match an empty String. In +this case, the regular expression does not match the empty substring at +the beginning or end of the input String, nor does it match the empty +substring at the end of the previous separator match. (For example, if +the regular expression matches the empty String, the String is split up +into individual code unit elements; the length of the result array +equals the length of the String, and each substring contains one code +unit.) Only the first match at a given index of the String is considered, even if backtracking could yield a non-empty-substring match at that index. (For example, /a*?/[Symbol.split]("ab") evaluates to the array ["a", "b"], while /a*/[Symbol.split]("ab") evaluates to the array ["","b"].)

        -

        If the string is (or converts to) the empty -String, the result depends on whether the regular expression can match -the empty String. If it can, the result array contains no elements. -Otherwise, the result array contains one element, which is the empty +

        If the string is (or converts to) the empty +String, the result depends on whether the regular expression can match +the empty String. If it can, the result array contains no elements. +Otherwise, the result array contains one element, which is the empty String.

        If the regular expression contains capturing parentheses, then each time separator is matched the results (including any undefined results) of the capturing parentheses are spliced into the output array. For example,

        /<(\/)?([^<>]+)>/[Symbol.split]("A<B>bold</B>and<CODE>coded</CODE>")
        @@ -32363,10 +32363,10 @@ String.

        21.2.6Properties of RegExp Instances

        -

        RegExp instances are ordinary objects that inherit properties -from the RegExp prototype object. RegExp instances have internal slots -[[RegExpMatcher]], [[OriginalSource]], and [[OriginalFlags]]. The value -of the [[RegExpMatcher]] internal slot is an implementation-dependent +

        RegExp instances are ordinary objects that inherit properties +from the RegExp prototype object. RegExp instances have internal slots +[[RegExpMatcher]], [[OriginalSource]], and [[OriginalFlags]]. The value +of the [[RegExpMatcher]] internal slot is an implementation-dependent representation of the Pattern of the RegExp object.

        Note

        Prior to ECMAScript 2015, RegExp instances were specified as having the own data properties source, global, ignoreCase, and multiline. Those properties are now specified as accessor properties of RegExp.prototype.

        @@ -32495,7 +32495,7 @@ representation of the Pattern

        22.1.3.1Array.prototype.concat ( ...arguments )

        -

        When the concat method is called with zero or +

        When the concat method is called with zero or more arguments, it returns an array containing the array elements of the object followed by the array elements of each argument in order.

        The following steps are taken:

        @@ -32503,7 +32503,7 @@ more arguments, it returns an array containing the array elements of the

      The "length" property of the concat method is 1.

      Note 1
      -

      The explicit setting of the "length" property +

      The explicit setting of the "length" property in step 6 is necessary to ensure that its value is correct in situations where the trailing elements of the result Array are not present.

       @@ -32695,10 +32695,10 @@ in step 6 is necessary to ensure that its value is correct in situations

      22.1.3.14Array.prototype.indexOf ( searchElement [ , fromIndex ] )

      Note 1

      indexOf compares searchElement to the elements of the array, in ascending order, using the Strict Equality Comparison algorithm, and if found at one or more indices, returns the smallest such index; otherwise, -1 is returned.

      -

      The optional second argument fromIndex defaults -to 0 (i.e. the whole array is searched). If it is greater than or equal -to the length of the array, -1 is returned, i.e. the array will not be -searched. If it is negative, it is used as the offset from the end of +

      The optional second argument fromIndex defaults +to 0 (i.e. the whole array is searched). If it is greater than or equal +to the length of the array, -1 is returned, i.e. the array will not be +searched. If it is negative, it is used as the offset from the end of the array to compute fromIndex. If the computed index is less than 0, the whole array will be searched.

      When the indexOf method is called with one or two arguments, the following steps are taken:

      @@ -32734,10 +32734,10 @@ the array to compute fromIndex. If the computed index is less than 0,

      22.1.3.17Array.prototype.lastIndexOf ( searchElement [ , fromIndex ] )

      Note 1

      lastIndexOf compares searchElement to the elements of the array in descending order using the Strict Equality Comparison algorithm, and if found at one or more indices, returns the largest such index; otherwise, -1 is returned.

      -

      The optional second argument fromIndex defaults -to the array's length minus one (i.e. the whole array is searched). If -it is greater than or equal to the length of the array, the whole array -will be searched. If it is negative, it is used as the offset from the +

      The optional second argument fromIndex defaults +to the array's length minus one (i.e. the whole array is searched). If +it is greater than or equal to the length of the array, the whole array +will be searched. If it is negative, it is used as the offset from the end of the array to compute fromIndex. If the computed index is less than 0, -1 is returned.

      When the lastIndexOf method is called with one or two arguments, the following steps are taken:

      @@ -32781,8 +32781,8 @@ end of the array to compute fromIndex. If the computed index is less

      22.1.3.20Array.prototype.push ( ...items )

      Note 1
      -

      The arguments are appended to the end of the array, in the -order in which they appear. The new length of the array is returned as +

      The arguments are appended to the end of the array, in the +order in which they appear. The new length of the array is returned as the result of the call.

      When the push method is called with zero or more arguments, the following steps are taken:

      @@ -32822,9 +32822,9 @@ the result of the call.

      1. Let O be ? ToObject(this value).
      2. Let len be ? ToLength(? Get(O, "length")).
      3. If IsCallable(callbackfn) is false, throw a TypeError exception.
      4. If len is 0 and initialValue is not present, throw a TypeError exception.
      5. Let k be len - 1.
      6. Let accumulator be undefined.
      7. If initialValue is present, then
        1. Set accumulator to initialValue.
      8. Else initialValue is not present,
        1. Let kPresent be false.
        2. Repeat, while kPresent is false and k ≥ 0
          1. Let Pk be ! ToString(k).
          2. Set kPresent to ? HasProperty(O, Pk).
          3. If kPresent is true, then
            1. Set accumulator to ? Get(O, Pk).
          4. Decrease k by 1.
        3. If kPresent is false, throw a TypeError exception.
      9. Repeat, while k ≥ 0
        1. Let Pk be ! ToString(k).
        2. Let kPresent be ? HasProperty(O, Pk).
        3. If kPresent is true, then
          1. Let kValue be ? Get(O, Pk).
          2. Set accumulator to ? Call(callbackfn, undefined, « accumulator, kValue, k, O »).
        4. Decrease k by 1.
      10. Return accumulator.
      Note 2
      -

      The reduceRight function is intentionally -generic; it does not require that its this value be an Array object. -Therefore it can be transferred to other kinds of objects for use as a +

      The reduceRight function is intentionally +generic; it does not require that its this value be an Array object. +Therefore it can be transferred to other kinds of objects for use as a method.

             @@ -32864,12 +32864,12 @@ method.

      1. Let O be ? ToObject(this value).
      2. Let len be ? ToLength(? Get(O, "length")).
      3. Let relativeStart be ? ToInteger(start).
      4. If relativeStart < 0, let k be max((len + relativeStart), 0); else let k be min(relativeStart, len).
      5. If end is undefined, let relativeEnd be len; else let relativeEnd be ? ToInteger(end).
      6. If relativeEnd < 0, let final be max((len + relativeEnd), 0); else let final be min(relativeEnd, len).
      7. Let count be max(final - k, 0).
      8. Let A be ? ArraySpeciesCreate(O, count).
      9. Let n be 0.
      10. Repeat, while k < final
        1. Let Pk be ! ToString(k).
        2. Let kPresent be ? HasProperty(O, Pk).
        3. If kPresent is true, then
          1. Let kValue be ? Get(O, Pk).
          2. Perform ? CreateDataPropertyOrThrow(A, ! ToString(n), kValue).
        4. Increase k by 1.
        5. Increase n by 1.
      11. Perform ? Set(A, "length", n, true).
      12. Return A.
      Note 2
      -

      The explicit setting of the "length" property -of the result Array in step 11 was necessary in previous editions of +

      The explicit setting of the "length" property +of the result Array in step 11 was necessary in previous editions of ECMAScript to ensure that its length was correct in situations where the trailing elements of the result Array were not present. Setting "length" - became unnecessary starting in ES2015 when the result Array was -initialized to its proper length rather than an empty Array but is + became unnecessary starting in ES2015 when the result Array was +initialized to its proper length rather than an empty Array but is carried forward to preserve backward compatibility.

       Note 3
      @@ -32896,8 +32896,8 @@ carried forward to preserve backward compatibility.

      22.1.3.27Array.prototype.sort ( comparefn )

      -

      The elements of this array are sorted. The sort must be -stable (that is, elements that compare equal must remain in their +

      The elements of this array are sorted. The sort must be +stable (that is, elements that compare equal must remain in their original order). If comparefn is not undefined, it should be a function that accepts two arguments x and y and returns a negative value if x < y, zero if x = y, or a positive value if x > y.

      Upon entry, the following steps are performed to initialize evaluation of the sort function:

      1. If comparefn is not undefined and IsCallable(comparefn) is false, throw a TypeError exception.
      2. Let obj be ? ToObject(this value).
      3. Let len be ? ToLength(? Get(obj, "length")). @@ -32906,75 +32906,75 @@ original order). If comparefn is not undefined, it
        1. For each integer i in the range 0 ≤ i < len, do
          1. Let elem be obj.[[GetOwnProperty]](! ToString(i)).
          2. If elem is undefined, return true.
        2. Return false.

        The sort order is the ordering, after completion of this function, of the integer-indexed property values of obj whose integer indexes are less than len. The result of the sort function is then determined as follows:

        -

        If comparefn is not undefined -and is not a consistent comparison function for the elements of this -array (see below), the sort order is implementation-defined. The sort +

        If comparefn is not undefined +and is not a consistent comparison function for the elements of this +array (see below), the sort order is implementation-defined. The sort order is also implementation-defined if comparefn is undefined and SortCompare does not act as a consistent comparison function.

        Let proto be obj.[[GetPrototypeOf]](). If proto is not null and there exists an integer j such that all of the conditions below are satisfied then the sort order is implementation-defined:

        The sort order is also implementation-defined if obj is sparse and any of the following conditions are true:

        The sort order is also implementation-defined if any of the following conditions are true:

        • If obj is an exotic object - (including Proxy exotic objects) whose behaviour for [[Get]], [[Set]], -[[Delete]], and [[GetOwnProperty]] is not the ordinary object + (including Proxy exotic objects) whose behaviour for [[Get]], [[Set]], +[[Delete]], and [[GetOwnProperty]] is not the ordinary object implementation of these internal methods. - +
        • If any index property of obj whose name is a nonnegative integer less than len is an accessor property or is a data property whose [[Writable]] attribute is false. - +
        • If comparefn is undefined and the application of ToString to any value passed as an argument to SortCompare modifies obj or any object on obj's prototype chain. - +
        • If comparefn is undefined and all applications of ToString, to any specific value passed as an argument to SortCompare, do not produce the same result. - +

        The following steps are taken:

        1. Perform an implementation-dependent sequence of calls to the [[Get]] and [[Set]] internal methods of obj, to the DeletePropertyOrThrow and HasOwnProperty abstract operation with obj as the first argument, and to SortCompare (described below), such that:
          • The property key argument for each call to [[Get]], [[Set]], HasOwnProperty, or DeletePropertyOrThrow is the string representation of a nonnegative integer less than len.
          • The arguments for calls to SortCompare - are values returned by a previous call to the [[Get]] internal method, -unless the properties accessed by those previous calls did not exist + are values returned by a previous call to the [[Get]] internal method, +unless the properties accessed by those previous calls did not exist according to HasOwnProperty. If both prospective arguments to SortCompare correspond to non-existent properties, use +0 instead of calling SortCompare. If only the first prospective argument is non-existent use +1. If only the second prospective argument is non-existent use -1.
          • If obj is not sparse then DeletePropertyOrThrow must not be called.
          • If any [[Set]] call returns false a TypeError exception is thrown.
          • If an abrupt completion is returned from any of these operations, it is immediately returned as the value of this function.
        2. Return obj.
        -

        Unless the sort order is specified above to be -implementation-defined, the returned object must have the following two +

        Unless the sort order is specified above to be +implementation-defined, the returned object must have the following two characteristics:

        • There must be some mathematical permutation π of the nonnegative integers less than len, such that for every nonnegative integer j less than len, if property old[j] existed, then new[π(j)] is exactly the same value as old[j]. But if property old[j] did not exist, then new[π(j)] does not exist. - +
        • Then for all nonnegative integers j and k, each less than len, if SortCompare(old[j], old[k]) < 0 (see SortCompare below), then new[π(j)] < new[π(k)]. - +

        Here the notation old[j] is used to refer to the hypothetical result of calling obj.[[Get]](j) before this function is executed, and the notation new[j] to refer to the hypothetical result of calling obj.[[Get]](j) after this function has been executed.

        @@ -32982,31 +32982,31 @@ characteristics:

        • Calling comparefn(a, b) always returns the same value v when given a specific pair of values a and b as its two arguments. Furthermore, Type(v) is Number, and v is not NaN. Note that this implies that exactly one of a <CF b, a =CF b, and a >CF b will be true for a given pair of a and b. - +
        • Calling comparefn(a, b) does not modify obj or any object on obj's prototype chain. - +
        • a =CF a (reflexivity) - +
        • If a =CF b, then b =CF a (symmetry) - +
        • If a =CF b and b =CF c, then a =CF c (transitivity of =CF) - +
        • If a <CF b and b <CF c, then a <CF c (transitivity of <CF) - +
        • If a >CF b and b >CF c, then a >CF c (transitivity of >CF) - +
        Note 1
        @@ -33037,17 +33037,17 @@ characteristics:

        The following steps are taken:

        1. Let O be ? ToObject(this value).
        2. Let len be ? ToLength(? Get(O, "length")).
        3. Let relativeStart be ? ToInteger(start).
        4. If relativeStart < 0, let actualStart be max((len + relativeStart), 0); else let actualStart be min(relativeStart, len).
        5. If the number of actual arguments is 0, then
          1. Let insertCount be 0.
          2. Let actualDeleteCount be 0.
        6. Else if the number of actual arguments is 1, then
          1. Let insertCount be 0.
          2. Let actualDeleteCount be len - actualStart.
        7. Else,
          1. Let insertCount be the number of actual arguments minus 2.
          2. Let dc be ? ToInteger(deleteCount).
          3. Let actualDeleteCount be min(max(dc, 0), len - actualStart).
        8. If len + insertCount - actualDeleteCount > 253 - 1, throw a TypeError exception.
        9. Let A be ? ArraySpeciesCreate(O, actualDeleteCount).
        10. Let k be 0.
        11. Repeat, while k < actualDeleteCount
          1. Let from be ! ToString(actualStart + k).
          2. Let fromPresent be ? HasProperty(O, from).
          3. If fromPresent is true, then
            1. Let fromValue be ? Get(O, from).
            2. Perform ? CreateDataPropertyOrThrow(A, ! ToString(k), fromValue).
          4. Increment k by 1.
        12. Perform ? Set(A, "length", actualDeleteCount, true).
        13. Let items be a List - whose elements are, in left to right order, the portion of the actual -argument list starting with the third argument. The list is empty if + whose elements are, in left to right order, the portion of the actual +argument list starting with the third argument. The list is empty if fewer than three arguments were passed.
        14. Let itemCount be the number of elements in items.
        15. If itemCount < actualDeleteCount, then
          1. Set k to actualStart.
          2. Repeat, while k < (len - actualDeleteCount)
            1. Let from be ! ToString(k + actualDeleteCount).
            2. Let to be ! ToString(k + itemCount).
            3. Let fromPresent be ? HasProperty(O, from).
            4. If fromPresent is true, then
              1. Let fromValue be ? Get(O, from).
              2. Perform ? Set(O, to, fromValue, true).
            5. Else fromPresent is false,
              1. Perform ? DeletePropertyOrThrow(O, to).
            6. Increase k by 1.
          3. Set k to len.
          4. Repeat, while k > (len - actualDeleteCount + itemCount)
            1. Perform ? DeletePropertyOrThrow(O, ! ToString(k - 1)).
            2. Decrease k by 1.
        16. Else if itemCount > actualDeleteCount, then
          1. Set k to (len - actualDeleteCount).
          2. Repeat, while k > actualStart
            1. Let from be ! ToString(k + actualDeleteCount - 1).
            2. Let to be ! ToString(k + itemCount - 1).
            3. Let fromPresent be ? HasProperty(O, from).
            4. If fromPresent is true, then
              1. Let fromValue be ? Get(O, from).
              2. Perform ? Set(O, to, fromValue, true).
            5. Else fromPresent is false,
              1. Perform ? DeletePropertyOrThrow(O, to).
            6. Decrease k by 1.
        17. Set k to actualStart.
        18. Repeat, while items is not empty
          1. Remove the first element from items and let E be the value of that element.
          2. Perform ? Set(O, ! ToString(k), E, true).
          3. Increase k by 1.
        19. Perform ? Set(O, "length", len - actualDeleteCount + itemCount, true).
        20. Return A.
        Note 2
        -

        The explicit setting of the "length" property -of the result Array in step 19 was necessary in previous editions of +

        The explicit setting of the "length" property +of the result Array in step 19 was necessary in previous editions of ECMAScript to ensure that its length was correct in situations where the trailing elements of the result Array were not present. Setting "length" - became unnecessary starting in ES2015 when the result Array was -initialized to its proper length rather than an empty Array but is + became unnecessary starting in ES2015 when the result Array was +initialized to its proper length rather than an empty Array but is carried forward to preserve backward compatibility.

         Note 3
        @@ -33058,27 +33058,27 @@ carried forward to preserve backward compatibility.

        22.1.3.29Array.prototype.toLocaleString ( [ reserved1 [ , reserved2 ] ] )

        An ECMAScript implementation that includes the ECMA-402 Internationalization API must implement the Array.prototype.toLocaleString - method as specified in the ECMA-402 specification. If an ECMAScript -implementation does not include the ECMA-402 API the following + method as specified in the ECMA-402 specification. If an ECMAScript +implementation does not include the ECMA-402 API the following specification of the toLocaleString method is used.

        Note 1

        The first edition of ECMA-402 did not include a replacement specification for the Array.prototype.toLocaleString method.

         -

        The meanings of the optional parameters to this method are -defined in the ECMA-402 specification; implementations that do not -include ECMA-402 support must not use those parameter positions for +

        The meanings of the optional parameters to this method are +defined in the ECMA-402 specification; implementations that do not +include ECMA-402 support must not use those parameter positions for anything else.

        The following steps are taken:

        1. Let array be ? ToObject(this value).
        2. Let len be ? ToLength(? Get(array, "length")).
        3. Let separator - be the String value for the list-separator String appropriate for the -host environment's current locale (this is derived in an + be the String value for the list-separator String appropriate for the +host environment's current locale (this is derived in an implementation-defined way).
        4. Let R be the empty String.
        5. Let k be 0.
        6. Repeat, while k < len
          1. If k > 0, then
            1. Set R to the string-concatenation of R and separator.
          2. Let nextElement be ? Get(array, ! ToString(k)).
          3. If nextElement is not undefined or null, then
            1. Let S be ? ToString(? Invoke(nextElement, "toLocaleString")).
            2. Set R to the string-concatenation of R and S.
          4. Increase k by 1.
        7. Return R.
        Note 2

        The elements of the array are converted to Strings using their toLocaleString - methods, and these Strings are then concatenated, separated by -occurrences of a separator String that has been derived in an -implementation-defined locale-specific way. The result of calling this + methods, and these Strings are then concatenated, separated by +occurrences of a separator String that has been derived in an +implementation-defined locale-specific way. The result of calling this function is intended to be analogous to the result of toString, except that the result of this function is intended to be locale-specific.

         Note 3
        @@ -33100,7 +33100,7 @@ function is intended to be analogous to the result of toString, exc

        22.1.3.31Array.prototype.unshift ( ...items )

        Note 1

        The arguments are prepended to the start of the array, such - that their order within the array is the same as the order in which + that their order within the array is the same as the order in which they appear in the argument list.

        When the unshift method is called with zero or more arguments item1, item2, etc., the following steps are taken:

        @@ -33133,7 +33133,7 @@ they appear in the argument list.

        This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.

        Note

        The own property names of this object are property names that were not included as standard properties of Array.prototype prior to the ECMAScript 2015 specification. These names are ignored for with - statement binding purposes in order to preserve the behaviour of + statement binding purposes in order to preserve the behaviour of existing code that might use one of these names as a binding in an outer scope that is shadowed by a with statement whose binding object is an Array object.

         @@ -33142,8 +33142,8 @@ existing code that might use one of these names as a binding in an outer

        22.1.4Properties of Array Instances

        -

        Array instances are Array exotic objects and have the internal -methods specified for such objects. Array instances inherit properties +

        Array instances are Array exotic objects and have the internal +methods specified for such objects. Array instances inherit properties from the Array prototype object.

        Array instances have a "length" property, and a set of enumerable properties with array index names.

        @@ -33153,7 +33153,7 @@ from the Array prototype object.

        The "length" property initially has the attributes { [[Writable]]: true, [[Enumerable]]: false, [[Configurable]]: false }.

        Note

        Reducing the value of the "length" property has the side-effect of deleting own array elements whose array index is between the old and new length values. However, non-configurable properties can not be deleted. Attempting to set the "length" property of an Array object to a value that is numerically less than or equal to the largest numeric own property name of an existing non-configurable array-indexed - property of the array will result in the length being set to a numeric + property of the array will result in the length being set to a numeric value that is one greater than that non-configurable numeric own property name. See 9.4.2.1.

                 @@ -33161,7 +33161,7 @@ value that is one greater than that non-configurable numeric own

        22.1.5Array Iterator Objects

        -

        An Array Iterator is an object, that represents a specific +

        An Array Iterator is an object, that represents a specific iteration over some specific Array instance object. There is not a named constructor for Array Iterator objects. Instead, Array iterator objects are created by calling certain methods of Array instance objects.

        @@ -33204,41 +33204,41 @@ iteration over some specific Array instance object. There is not a named
      @@ -33257,292 +33257,292 @@ iteration over some specific Array instance object. There is not a named
      Internal Slot - + Description - +
      [[IteratedObject]] - + The object whose array elements are being iterated. - +
      [[ArrayIteratorNextIndex]] - + The integer index of the next integer index to be examined by this iteration. - +
      [[ArrayIterationKind]] - + A String value that identifies what is returned for each element of the iteration. The possible values are: "key", "value", "key+value". - +
      Constructor Name and Intrinsic - + Element Type - + Element Size - + Conversion Operation - + Description - + Equivalent C Type - +
      Int8Array - +
      %Int8Array% - +       		Int8 - + 1 - + ToInt8 - + 8-bit 2's complement signed integer - + signed char - +
      Uint8Array - +
      %Uint8Array% - +       		Uint8 - + 1 - + ToUint8 - + 8-bit unsigned integer - + unsigned char - +
      Uint8ClampedArray - +
      %Uint8ClampedArray% - +       		Uint8C - + 1 - + ToUint8Clamp - + 8-bit unsigned integer (clamped conversion) - + unsigned char - +
      Int16Array - +
      %Int16Array% - +       		Int16 - + 2 - + ToInt16 - + 16-bit 2's complement signed integer - + short - +
      Uint16Array - +
      %Uint16Array% - +       		Uint16 - + 2 - + ToUint16 - + 16-bit unsigned integer - + unsigned short - +
      Int32Array - +
      %Int32Array% - +       		Int32 - + 4 - + ToInt32 - + 32-bit 2's complement signed integer - + int - +
      Uint32Array - +
      %Uint32Array% - +       		Uint32 - + 4 - + ToUint32 - + 32-bit unsigned integer - + unsigned int - +
      Float32Array - +
      %Float32Array% - +       		Float32 - + 4 - + 32-bit IEEE floating point - + float - +
      Float64Array - +
      %Float64Array% - +       		Float64 - + 8 - + 64-bit IEEE floating point - + double - +

      In the definitions below, references to TypedArray should be replaced with the appropriate constructor - name from the above table. The phrase “the element size in bytes” -refers to the value in the Element Size column of the table in the row + name from the above table. The phrase “the element size in bytes” +refers to the value in the Element Size column of the table in the row corresponding to the constructor. The phrase “element Type” refers to the value in the Element Type column for that row.

      @@ -33677,9 +33677,9 @@ corresponding to the

      22.2.3.7%TypedArray%.prototype.every ( callbackfn [ , thisArg ] )

      %TypedArray%.prototype.every is a distinct function that implements the same algorithm as Array.prototype.every as defined in 22.1.3.5 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this - value is an object that has a fixed length and whose integer-indexed + value is an object that has a fixed length and whose integer-indexed properties are not sparse. However, such optimization must not introduce - any observable changes in the specified behaviour of the algorithm and + any observable changes in the specified behaviour of the algorithm and must take into account the possibility that calls to callbackfn may cause the this value to become detached.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33704,8 +33704,8 @@ must take into account the possibility that calls to callbackfn may c

      22.2.3.10%TypedArray%.prototype.find ( predicate [ , thisArg ] )

      %TypedArray%.prototype.find is a distinct function that implements the same algorithm as Array.prototype.find as defined in 22.1.3.8 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm and must take into account the possibility that calls to predicate may cause the this value to become detached.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33713,8 +33713,8 @@ algorithm and must take into account the possibility that calls to predicat

      22.2.3.11%TypedArray%.prototype.findIndex ( predicate [ , thisArg ] )

      %TypedArray%.prototype.findIndex is a distinct function that implements the same algorithm as Array.prototype.findIndex as defined in 22.1.3.9 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm and must take into account the possibility that calls to predicate may cause the this value to become detached.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33722,8 +33722,8 @@ algorithm and must take into account the possibility that calls to predicat

      22.2.3.12%TypedArray%.prototype.forEach ( callbackfn [ , thisArg ] )

      %TypedArray%.prototype.forEach is a distinct function that implements the same algorithm as Array.prototype.forEach as defined in 22.1.3.12 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm and must take into account the possibility that calls to callbackfn may cause the this value to become detached.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33731,8 +33731,8 @@ algorithm and must take into account the possibility that calls to callback

      22.2.3.13%TypedArray%.prototype.includes ( searchElement [ , fromIndex ] )

      %TypedArray%.prototype.includes is a distinct function that implements the same algorithm as Array.prototype.includes as defined in 22.1.3.13 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33740,8 +33740,8 @@ algorithm.

      22.2.3.14%TypedArray%.prototype.indexOf ( searchElement [ , fromIndex ] )

      %TypedArray%.prototype.indexOf is a distinct function that implements the same algorithm as Array.prototype.indexOf as defined in 22.1.3.14 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33749,8 +33749,8 @@ algorithm.

      22.2.3.15%TypedArray%.prototype.join ( separator )

      %TypedArray%.prototype.join is a distinct function that implements the same algorithm as Array.prototype.join as defined in 22.1.3.15 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33765,8 +33765,8 @@ algorithm.

      22.2.3.17%TypedArray%.prototype.lastIndexOf ( searchElement [ , fromIndex ] )

      %TypedArray%.prototype.lastIndexOf is a distinct function that implements the same algorithm as Array.prototype.lastIndexOf as defined in 22.1.3.17 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33791,8 +33791,8 @@ algorithm.

      22.2.3.20%TypedArray%.prototype.reduce ( callbackfn [ , initialValue ] )

      %TypedArray%.prototype.reduce is a distinct function that implements the same algorithm as Array.prototype.reduce as defined in 22.1.3.21 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm and must take into account the possibility that calls to callbackfn may cause the this value to become detached.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33800,8 +33800,8 @@ algorithm and must take into account the possibility that calls to callback

      22.2.3.21%TypedArray%.prototype.reduceRight ( callbackfn [ , initialValue ] )

      %TypedArray%.prototype.reduceRight is a distinct function that implements the same algorithm as Array.prototype.reduceRight as defined in 22.1.3.22 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm and must take into account the possibility that calls to callbackfn may cause the this value to become detached.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33809,8 +33809,8 @@ algorithm and must take into account the possibility that calls to callback

      22.2.3.22%TypedArray%.prototype.reverse ( )

      %TypedArray%.prototype.reverse is a distinct function that implements the same algorithm as Array.prototype.reverse as defined in 22.1.3.23 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33846,8 +33846,8 @@ algorithm.

      22.2.3.25%TypedArray%.prototype.some ( callbackfn [ , thisArg ] )

      %TypedArray%.prototype.some is a distinct function that implements the same algorithm as Array.prototype.some as defined in 22.1.3.26 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm and must take into account the possibility that calls to callbackfn may cause the this value to become detached.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

       @@ -33880,8 +33880,8 @@ algorithm and must take into account the possibility that calls to callback

      22.2.3.28%TypedArray%.prototype.toLocaleString ( [ reserved1 [ , reserved2 ] ] )

      %TypedArray%.prototype.toLocaleString is a distinct function that implements the same algorithm as Array.prototype.toLocaleString as defined in 22.1.3.29 except that the this object's [[ArrayLength]] internal slot is accessed in place of performing a [[Get]] of "length". The implementation of the algorithm may be optimized with the knowledge that the this value is an object that has a fixed length and whose integer-indexed - properties are not sparse. However, such optimization must not -introduce any observable changes in the specified behaviour of the + properties are not sparse. However, such optimization must not +introduce any observable changes in the specified behaviour of the algorithm.

      This function is not generic. ValidateTypedArray is applied to the this value prior to evaluating the algorithm. If its result is an abrupt completion that exception is thrown instead of evaluating the algorithm.

      Note
      @@ -33921,8 +33921,8 @@ algorithm.

      Each TypedArray constructor:

      • is an intrinsic object that has the structure described below, differing only in the name used as the constructor name instead of TypedArray, in Table 59.
        • -
      • is a single function whose behaviour is overloaded based -upon the number and types of its arguments. The actual behaviour of a +
      • is a single function whose behaviour is overloaded based +upon the number and types of its arguments. The actual behaviour of a call of TypedArray depends upon the number and kind of arguments that are passed to it.
      • is not intended to be called as a function and will throw an exception when called in that manner.
      • is designed to be subclassable. It may be used as the value of an extends clause of a class definition. Subclass constructors that intend to inherit the specified TypedArray behaviour must include a super call to the TypedArray constructor to create and initialize the subclass instance with the internal state necessary to support the %TypedArray%.prototype built-in methods.
        • @@ -33947,7 +33947,7 @@ call of TypedArray depends upon the number and kind of arguments that

        22.2.4.2.1Runtime Semantics: AllocateTypedArray ( constructorName, newTarget, defaultProto [ , length ] )

        The abstract operation AllocateTypedArray with arguments constructorName, newTarget, defaultProto and optional argument length is used to validate and create an instance of a TypedArray constructor. constructorName is required to be the name of a TypedArray constructor in Table 59. If the length argument is passed, an ArrayBuffer of that length is also allocated and - associated with the new TypedArray instance. AllocateTypedArray + associated with the new TypedArray instance. AllocateTypedArray provides common semantics that is used by all of the TypedArray overloads. AllocateTypedArray performs the following steps:

        1. Let proto be ? GetPrototypeFromConstructor(newTarget, defaultProto).
        2. Let obj be IntegerIndexedObjectCreate(proto, « [[ViewedArrayBuffer]], [[TypedArrayName]], [[ByteLength]], [[ByteOffset]], [[ArrayLength]] »).
        3. Assert: obj.[[ViewedArrayBuffer]] is undefined.
        4. Set obj.[[TypedArrayName]] to constructorName.
        5. If length is not present, then
          1. Set obj.[[ByteLength]] to 0.
          2. Set obj.[[ByteOffset]] to 0.
          3. Set obj.[[ArrayLength]] to 0.
        6. Else,
          1. Perform ? AllocateTypedArrayBuffer(obj, length).
        7. Return obj.
        @@ -33963,9 +33963,9 @@ provides common semantics that is used by all of the TypedArray overl

        22.2.4.3TypedArray ( typedArray )

        -

        This description applies only if the TypedArray -function is called with at least one argument and the Type of the first -argument is Object and that object has a [[TypedArrayName]] internal +

        This description applies only if the TypedArray +function is called with at least one argument and the Type of the first +argument is Object and that object has a [[TypedArrayName]] internal slot.

        TypedArray called with argument typedArray performs the following steps:

        1. Assert: Type(typedArray) is Object and typedArray has a [[TypedArrayName]] internal slot.
        2. If NewTarget is undefined, throw a TypeError exception.
        3. Let constructorName be the String value of the Constructor Name value specified in Table 59 for this TypedArray constructor.
        4. Let O be ? AllocateTypedArray(constructorName, NewTarget, "%TypedArrayPrototype%").
        5. Let srcArray be typedArray.
        6. Let srcData be srcArray.[[ViewedArrayBuffer]].
        7. If IsDetachedBuffer(srcData) is true, throw a TypeError exception.
        8. Let elementType be the String value of the Element Type value in Table 59 for constructorName.
        9. Let elementLength be srcArray.[[ArrayLength]].
        10. Let srcName be the String value of srcArray.[[TypedArrayName]].
        11. Let srcType be the String value of the Element Type value in Table 59 for srcName.
        12. Let srcElementSize be the Element Size value in Table 59 for srcName.
        13. Let srcByteOffset be srcArray.[[ByteOffset]].
        14. Let elementSize be the Element Size value in Table 59 for constructorName.
        15. Let byteLength be elementSize × elementLength.
        16. If IsSharedArrayBuffer(srcData) is false, then
          1. Let bufferConstructor be ? SpeciesConstructor(srcData, %ArrayBuffer%).
        17. Else,
          1. Let bufferConstructor be %ArrayBuffer%.
        18. If SameValue(elementType, srcType) is true, then
          1. Let data be ? CloneArrayBuffer(srcData, srcByteOffset, byteLength, bufferConstructor).
        19. Else,
          1. Let data be ? AllocateArrayBuffer(bufferConstructor, byteLength).
          2. If IsDetachedBuffer(srcData) is true, throw a TypeError exception.
          3. Let srcByteIndex be srcByteOffset.
          4. Let targetByteIndex be 0.
          5. Let count be elementLength.
          6. Repeat, while count > 0
            1. Let value be GetValueFromBuffer(srcData, srcByteIndex, srcType, true, "Unordered").
            2. Perform SetValueInBuffer(data, targetByteIndex, elementType, value, true, "Unordered").
            3. Set srcByteIndex to srcByteIndex + srcElementSize.
            4. Set targetByteIndex to targetByteIndex + elementSize.
            5. Decrement count by 1.
        20. Set O.[[ViewedArrayBuffer]] to data.
        21. Set O.[[ByteLength]] to byteLength.
        22. Set O.[[ByteOffset]] to 0.
        23. Set O.[[ArrayLength]] to elementLength.
        24. Return O. @@ -33974,9 +33974,9 @@ slot.

          22.2.4.4TypedArray ( object )

          -

          This description applies only if the TypedArray -function is called with at least one argument and the Type of the first -argument is Object and that object does not have either a +

          This description applies only if the TypedArray +function is called with at least one argument and the Type of the first +argument is Object and that object does not have either a [[TypedArrayName]] or an [[ArrayBufferData]] internal slot.

          TypedArray called with argument object performs the following steps:

          1. Assert: Type(object) is Object and object does not have either a [[TypedArrayName]] or an [[ArrayBufferData]] internal slot.
          2. If NewTarget is undefined, throw a TypeError exception.
          3. Let constructorName be the String value of the Constructor Name value specified in Table 59 for this TypedArray constructor.
          4. Let O be ? AllocateTypedArray(constructorName, NewTarget, "%TypedArrayPrototype%").
          5. Let usingIterator be ? GetMethod(object, @@iterator).
          6. If usingIterator is not undefined, then
            1. Let values be ? IterableToList(object, usingIterator).
            2. Let len be the number of elements in values.
            3. Perform ? AllocateTypedArrayBuffer(O, len).
            4. Let k be 0.
            5. Repeat, while k < len
              1. Let Pk be ! ToString(k).
              2. Let kValue be the first element of values and remove that element from values.
              3. Perform ? Set(O, Pk, kValue, true).
              4. Increase k by 1.
            6. Assert: values is now an empty List.
            7. Return O.
          7. NOTE: object is not an Iterable so assume it is already an array-like object.
          8. Let arrayLike be object.
          9. Let len be ? ToLength(? Get(arrayLike, "length")).
          10. Perform ? AllocateTypedArrayBuffer(O, len).
          11. Let k be 0.
          12. Repeat, while k < len
            1. Let Pk be ! ToString(k).
            2. Let kValue be ? Get(arrayLike, Pk).
            3. Perform ? Set(O, Pk, kValue, true).
            4. Increase k by 1.
          13. Return O. @@ -33985,9 +33985,9 @@ argument is Object and that object does not have either a

            22.2.4.5TypedArray ( buffer [ , byteOffset [ , length ] ] )

            -

            This description applies only if the TypedArray -function is called with at least one argument and the Type of the first -argument is Object and that object has an [[ArrayBufferData]] internal +

            This description applies only if the TypedArray +function is called with at least one argument and the Type of the first +argument is Object and that object has an [[ArrayBufferData]] internal slot.

            TypedArray called with at least one argument buffer performs the following steps:

            1. Assert: Type(buffer) is Object and buffer has an [[ArrayBufferData]] internal slot.
            2. If NewTarget is undefined, throw a TypeError exception.
            3. Let constructorName be the String value of the Constructor Name value specified in Table 59 for this TypedArray constructor.
            4. Let O be ? AllocateTypedArray(constructorName, NewTarget, "%TypedArrayPrototype%").
            5. Let elementSize be the Number value of the Element Size value in Table 59 for constructorName.
            6. Let offset be ? ToIndex(byteOffset).
            7. If offset modulo elementSize ≠ 0, throw a RangeError exception.
            8. If length is present and length is not undefined, then
              1. Let newLength be ? ToIndex(length).
            9. If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
            10. Let bufferByteLength be buffer.[[ArrayBufferByteLength]].
            11. If length is either not present or undefined, then
              1. If bufferByteLength modulo elementSize ≠ 0, throw a RangeError exception.
              2. Let newByteLength be bufferByteLength - offset.
              3. If newByteLength < 0, throw a RangeError exception.
            12. Else,
              1. Let newByteLength be newLength × elementSize.
              2. If offset + newByteLength > bufferByteLength, throw a RangeError exception.
            13. Set O.[[ViewedArrayBuffer]] to buffer.
            14. Set O.[[ByteLength]] to newByteLength.
            15. Set O.[[ByteOffset]] to offset.
            16. Set O.[[ArrayLength]] to newByteLength / elementSize.
            17. Return O. @@ -34055,8 +34055,8 @@ slot.

              22.2.7Properties of TypedArray Instances

              TypedArray instances are Integer-Indexed exotic objects. Each TypedArray instance inherits properties from the corresponding TypedArray prototype object. Each TypedArray - instance has the following internal slots: [[TypedArrayName]], -[[ViewedArrayBuffer]], [[ByteLength]], [[ByteOffset]], and + instance has the following internal slots: [[TypedArrayName]], +[[ViewedArrayBuffer]], [[ByteLength]], [[ByteOffset]], and [[ArrayLength]].

               @@ -34067,15 +34067,15 @@ slot.

              23.1Map Objects

              -

              Map objects are collections of key/value pairs where both the -keys and values may be arbitrary ECMAScript language values. A distinct -key value may only occur in one key/value pair within the Map's +

              Map objects are collections of key/value pairs where both the +keys and values may be arbitrary ECMAScript language values. A distinct +key value may only occur in one key/value pair within the Map's collection. Distinct key values are discriminated using the SameValueZero comparison algorithm.

              -

              Map object must be implemented using either hash tables or other -mechanisms that, on average, provide access times that are sublinear on -the number of elements in the collection. The data structures used in +

              Map object must be implemented using either hash tables or other +mechanisms that, on average, provide access times that are sublinear on +the number of elements in the collection. The data structures used in this Map objects specification is only intended to describe the required - observable semantics of Map objects. It is not intended to be a viable + observable semantics of Map objects. It is not intended to be a viable implementation model.

              @@ -34095,8 +34095,8 @@ implementation model.

              1. If NewTarget is undefined, throw a TypeError exception.
              2. Let map be ? OrdinaryCreateFromConstructor(NewTarget, "%MapPrototype%", « [[MapData]] »).
              3. Set map.[[MapData]] to a new empty List.
              4. If iterable is not present, or is either undefined or null, return map.
              5. Let adder be ? Get(map, "set").
              6. Return ? AddEntriesFromIterable(map, iterable, adder).
              Note
              -

              If the parameter iterable is present, it is -expected to be an object that implements an @@iterator method that +

              If the parameter iterable is present, it is +expected to be an object that implements an @@iterator method that returns an iterator object that produces a two element array-like object whose first element is a value that will be used as a Map key and whose second element is the value to associate with that key.

              @@ -34109,10 +34109,10 @@ returns an iterator object that produces a two element array-like object
              1. If IsCallable(adder) is false, throw a TypeError exception.
              2. Assert: iterable is present, and is neither undefined nor null.
              3. Let iteratorRecord be ? GetIterator(iterable).
              4. Repeat,
                1. Let next be ? IteratorStep(iteratorRecord).
                2. If next is false, return target.
                3. Let nextItem be ? IteratorValue(next).
                4. If Type(nextItem) is not Object, then
                  1. Let error be ThrowCompletion(a newly created TypeError object).
                  2. Return ? IteratorClose(iteratorRecord, error).
                5. Let k be Get(nextItem, "0").
                6. If k is an abrupt completion, return ? IteratorClose(iteratorRecord, k).
                7. Let v be Get(nextItem, "1").
                8. If v is an abrupt completion, return ? IteratorClose(iteratorRecord, v).
                9. Let status be Call(adder, target, « k.[[Value]], v.[[Value]] »).
                10. If status is an abrupt completion, return ? IteratorClose(iteratorRecord, status).
              Note
              -

              The parameter iterable is expected to be an -object that implements an @@iterator method that returns an iterator +

              The parameter iterable is expected to be an +object that implements an @@iterator method that returns an iterator object that produces a two element array-like object whose first element - is a value that will be used as a Map key and whose second element is + is a value that will be used as a Map key and whose second element is the value to associate with that key.

               @@ -34175,9 +34175,9 @@ the value to associate with that key.

              1. Let M be the this value.
              2. If Type(M) is not Object, throw a TypeError exception.
              3. If M does not have a [[MapData]] internal slot, throw a TypeError exception.
              4. Let entries be the List that is M.[[MapData]].
              5. For each Record { [[Key]], [[Value]] } p that is an element of entries, do
                1. If p.[[Key]] is not empty and SameValueZero(p.[[Key]], key) is true, then
                  1. Set p.[[Key]] to empty.
                  2. Set p.[[Value]] to empty.
                  3. Return true.
              6. Return false.
              Note
              -

              The value empty is used as a -specification device to indicate that an entry has been deleted. Actual -implementations may take other actions such as physically removing the +

              The value empty is used as a +specification device to indicate that an entry has been deleted. Actual +implementations may take other actions such as physically removing the entry from internal data structures.

               @@ -34305,42 +34305,42 @@ entry from internal data structures.

              Internal Slot - + Description - + [[Map]] - + The Map object that is being iterated. - + [[MapNextIndex]] - + The integer index of the next Map data element to be examined by this iterator. - + [[MapIterationKind]] - + - A String value that identifies what is to be returned + A String value that identifies what is to be returned for each element of the iteration. The possible values are: "key", "value", "key+value". - + @@ -34352,14 +34352,14 @@ for each element of the iteration. The possible values are: "key",

              23.2Set Objects

              -

              Set objects are collections of ECMAScript language values. A -distinct value may only occur once as an element of a Set's collection. +

              Set objects are collections of ECMAScript language values. A +distinct value may only occur once as an element of a Set's collection. Distinct values are discriminated using the SameValueZero comparison algorithm.

              Set objects must be implemented using either hash tables or other mechanisms that, on average, provide access times that are sublinear on - the number of elements in the collection. The data structures used in + the number of elements in the collection. The data structures used in this Set objects specification is only intended to describe the required - observable semantics of Set objects. It is not intended to be a viable + observable semantics of Set objects. It is not intended to be a viable implementation model.

              @@ -34445,9 +34445,9 @@ implementation model.

              1. Let S be the this value.
              2. If Type(S) is not Object, throw a TypeError exception.
              3. If S does not have a [[SetData]] internal slot, throw a TypeError exception.
              4. Let entries be the List that is S.[[SetData]].
              5. For each e that is an element of entries, do
                1. If e is not empty and SameValueZero(e, value) is true, then
                  1. Replace the element of entries whose value is e with an element whose value is empty.
                  2. Return true.
              6. Return false.
              Note
              -

              The value empty is used as a -specification device to indicate that an entry has been deleted. Actual -implementations may take other actions such as physically removing the +

              The value empty is used as a +specification device to indicate that an entry has been deleted. Actual +implementations may take other actions such as physically removing the entry from internal data structures.

                             @@ -34470,14 +34470,14 @@ entry from internal data structures.

              Note

              callbackfn should be a function that accepts three arguments. forEach calls callbackfn once for each value present in the set object, in value insertion order. callbackfn is called only for values of the Set which actually exist; it is not called for keys that have been deleted from the set.

              If a thisArg parameter is provided, it will be used as the this value for each invocation of callbackfn. If it is not provided, undefined is used instead.

              -

              callbackfn is called with three arguments: the -first two arguments are a value contained in the Set. The same value is -passed for both arguments. The Set object being traversed is passed as +

              callbackfn is called with three arguments: the +first two arguments are a value contained in the Set. The same value is +passed for both arguments. The Set object being traversed is passed as the third argument.

              The callbackfn is called with three arguments to be consistent with the call back functions used by forEach methods for Map and Array. For Sets, each item value is considered to be both the key and the value.

              forEach does not directly mutate the object on which it is called but the object may be mutated by the calls to callbackfn.

              -

              Each value is normally visited only once. However, a value -will be revisited if it is deleted after it has been visited and then +

              Each value is normally visited only once. However, a value +will be revisited if it is deleted after it has been visited and then re-added before the forEach call completes. Values that are deleted after the call to forEach begins and before being visited are not visited unless the value is added again before the forEach call completes. New values added after the call to forEach begins are visited.

                             @@ -34531,8 +34531,8 @@ re-added before the forEach call completes. Values that are deleted

              23.2.5Set Iterator Objects

              -

              A Set Iterator is an ordinary object, with the structure -defined below, that represents a specific iteration over some specific +

              A Set Iterator is an ordinary object, with the structure +defined below, that represents a specific iteration over some specific Set instance object. There is not a named constructor for Set Iterator objects. Instead, set iterator objects are created by calling certain methods of Set instance objects.

              @@ -34574,42 +34574,42 @@ Set instance object. There is not a named integer index of the next Set data element to be examined by this iterator - + [[SetIterationKind]] - + - A String value that identifies what is to be returned + A String value that identifies what is to be returned for each element of the iteration. The possible values are: "key", "value", "key+value". "key" and "value" have the same meaning. - + @@ -34622,43 +34622,43 @@ for each element of the iteration. The possible values are: "key",

              23.3WeakMap Objects

              WeakMap objects are collections of key/value pairs where the keys - are objects and values may be arbitrary ECMAScript language values. A -WeakMap may be queried to see if it contains a key/value pair with a -specific key, but no mechanism is provided for enumerating the objects -it holds as keys. If an object that is being used as the key of a -WeakMap key/value pair is only reachable by following a chain of -references that start within that WeakMap, then that key/value pair is -inaccessible and is automatically removed from the WeakMap. WeakMap -implementations must detect and remove such key/value pairs and any + are objects and values may be arbitrary ECMAScript language values. A +WeakMap may be queried to see if it contains a key/value pair with a +specific key, but no mechanism is provided for enumerating the objects +it holds as keys. If an object that is being used as the key of a +WeakMap key/value pair is only reachable by following a chain of +references that start within that WeakMap, then that key/value pair is +inaccessible and is automatically removed from the WeakMap. WeakMap +implementations must detect and remove such key/value pairs and any associated resources.

              -

              An implementation may impose an arbitrarily determined latency -between the time a key/value pair of a WeakMap becomes inaccessible and -the time when the key/value pair is removed from the WeakMap. If this -latency was observable to ECMAScript program, it would be a source of -indeterminacy that could impact program execution. For that reason, an +

              An implementation may impose an arbitrarily determined latency +between the time a key/value pair of a WeakMap becomes inaccessible and +the time when the key/value pair is removed from the WeakMap. If this +latency was observable to ECMAScript program, it would be a source of +indeterminacy that could impact program execution. For that reason, an ECMAScript implementation must not provide any means to observe a key of - a WeakMap that does not require the observer to present the observed + a WeakMap that does not require the observer to present the observed key.

              -

              WeakMap objects must be implemented using either hash tables or -other mechanisms that, on average, provide access times that are -sublinear on the number of key/value pairs in the collection. The data -structure used in this WeakMap objects specification are only intended -to describe the required observable semantics of WeakMap objects. It is +

              WeakMap objects must be implemented using either hash tables or +other mechanisms that, on average, provide access times that are +sublinear on the number of key/value pairs in the collection. The data +structure used in this WeakMap objects specification are only intended +to describe the required observable semantics of WeakMap objects. It is not intended to be a viable implementation model.

              Note
              -

              WeakMap and WeakSets are intended to provide mechanisms for -dynamically associating state with an object in a manner that does not -“leak” memory resources if, in the absence of the WeakMap or WeakSet, -the object otherwise became inaccessible and subject to resource -reclamation by the implementation's garbage collection mechanisms. This -characteristic can be achieved by using an inverted per-object mapping -of weak map instances to keys. Alternatively each weak map may -internally store its key to value mappings but this approach requires -coordination between the WeakMap or WeakSet implementation and the -garbage collector. The following references describe mechanism that may +

              WeakMap and WeakSets are intended to provide mechanisms for +dynamically associating state with an object in a manner that does not +“leak” memory resources if, in the absence of the WeakMap or WeakSet, +the object otherwise became inaccessible and subject to resource +reclamation by the implementation's garbage collection mechanisms. This +characteristic can be achieved by using an inverted per-object mapping +of weak map instances to keys. Alternatively each weak map may +internally store its key to value mappings but this approach requires +coordination between the WeakMap or WeakSet implementation and the +garbage collector. The following references describe mechanism that may be useful to implementations of WeakMap and WeakSets:

              Barry Hayes. 1997. Ephemerons: a new finalization mechanism. In Proceedings of the 12th ACM SIGPLAN conference on Object-oriented programming, systems, languages, and applications (OOPSLA '97), A. Michael Berman (Ed.). ACM, New York, NY, USA, 176-183, http://doi.acm.org/10.1145/263698.263733.

              -

              Alexandra Barros, Roberto Ierusalimschy, Eliminating Cycles in +

              Alexandra Barros, Roberto Ierusalimschy, Eliminating Cycles in Weak Tables. Journal of Universal Computer Science - J.UCS, vol. 14, no. 21, pp. 3481-3497, 2008, http://www.jucs.org/jucs_14_21/eliminating_cycles_in_weak

               @@ -34680,10 +34680,10 @@ Weak Tables. Journal of Universal Computer Science - J.UCS, vol. 14, no.
              1. If NewTarget is undefined, throw a TypeError exception.
              2. Let map be ? OrdinaryCreateFromConstructor(NewTarget, "%WeakMapPrototype%", « [[WeakMapData]] »).
              3. Set map.[[WeakMapData]] to a new empty List.
              4. If iterable is not present, or is either undefined or null, return map.
              5. Let adder be ? Get(map, "set").
              6. Return ? AddEntriesFromIterable(map, iterable, adder).
              Note
              -

              If the parameter iterable is present, it is -expected to be an object that implements an @@iterator method that +

              If the parameter iterable is present, it is +expected to be an object that implements an @@iterator method that returns an iterator object that produces a two element array-like object - whose first element is a value that will be used as a WeakMap key and + whose first element is a value that will be used as a WeakMap key and whose second element is the value to associate with that key.

                             @@ -34725,9 +34725,9 @@ whose second element is the value to associate with that key.

              1. Let M be the this value.
              2. If Type(M) is not Object, throw a TypeError exception.
              3. If M does not have a [[WeakMapData]] internal slot, throw a TypeError exception.
              4. Let entries be the List that is M.[[WeakMapData]].
              5. If Type(key) is not Object, return false.
              6. For each Record { [[Key]], [[Value]] } p that is an element of entries, do
                1. If p.[[Key]] is not empty and SameValue(p.[[Key]], key) is true, then
                  1. Set p.[[Key]] to empty.
                  2. Set p.[[Value]] to empty.
                  3. Return true.
              7. Return false.
              Note
              -

              The value empty is used as a -specification device to indicate that an entry has been deleted. Actual -implementations may take other actions such as physically removing the +

              The value empty is used as a +specification device to indicate that an entry has been deleted. Actual +implementations may take other actions such as physically removing the entry from internal data structures.

                             @@ -34762,8 +34762,8 @@ entry from internal data structures.

              23.3.4Properties of WeakMap Instances

              -

              WeakMap instances are ordinary objects that inherit properties -from the WeakMap prototype. WeakMap instances also have a +

              WeakMap instances are ordinary objects that inherit properties +from the WeakMap prototype. WeakMap instances also have a [[WeakMapData]] internal slot.

                             @@ -34771,27 +34771,27 @@ from the WeakMap prototype. WeakMap instances also have a

              23.4WeakSet Objects

              WeakSet objects are collections of objects. A distinct object may - only occur once as an element of a WeakSet's collection. A WeakSet may -be queried to see if it contains a specific object, but no mechanism is -provided for enumerating the objects it holds. If an object that is -contained by a WeakSet is only reachable by following a chain of -references that start within that WeakSet, then that object is -inaccessible and is automatically removed from the WeakSet. WeakSet -implementations must detect and remove such objects and any associated + only occur once as an element of a WeakSet's collection. A WeakSet may +be queried to see if it contains a specific object, but no mechanism is +provided for enumerating the objects it holds. If an object that is +contained by a WeakSet is only reachable by following a chain of +references that start within that WeakSet, then that object is +inaccessible and is automatically removed from the WeakSet. WeakSet +implementations must detect and remove such objects and any associated resources.

              -

              An implementation may impose an arbitrarily determined latency -between the time an object contained in a WeakSet becomes inaccessible -and the time when the object is removed from the WeakSet. If this -latency was observable to ECMAScript program, it would be a source of -indeterminacy that could impact program execution. For that reason, an -ECMAScript implementation must not provide any means to determine if a -WeakSet contains a particular object that does not require the observer +

              An implementation may impose an arbitrarily determined latency +between the time an object contained in a WeakSet becomes inaccessible +and the time when the object is removed from the WeakSet. If this +latency was observable to ECMAScript program, it would be a source of +indeterminacy that could impact program execution. For that reason, an +ECMAScript implementation must not provide any means to determine if a +WeakSet contains a particular object that does not require the observer to present the observed object.

              -

              WeakSet objects must be implemented using either hash tables or -other mechanisms that, on average, provide access times that are -sublinear on the number of elements in the collection. The data +

              WeakSet objects must be implemented using either hash tables or +other mechanisms that, on average, provide access times that are +sublinear on the number of elements in the collection. The data structure used in this WeakSet objects specification is only intended to - describe the required observable semantics of WeakSet objects. It is + describe the required observable semantics of WeakSet objects. It is not intended to be a viable implementation model.

              Note

              See the NOTE in 23.3.

              @@ -34859,9 +34859,9 @@ not intended to be a viable implementation model.

              1. Let S be the this value.
              2. If Type(S) is not Object, throw a TypeError exception.
              3. If S does not have a [[WeakSetData]] internal slot, throw a TypeError exception.
              4. If Type(value) is not Object, return false.
              5. Let entries be the List that is S.[[WeakSetData]].
              6. For each e that is an element of entries, do
                1. If e is not empty and SameValue(e, value) is true, then
                  1. Replace the element of entries whose value is e with an element whose value is empty.
                  2. Return true.
              7. Return false.
              Note
              -

              The value empty is used as a -specification device to indicate that an entry has been deleted. Actual -implementations may take other actions such as physically removing the +

              The value empty is used as a +specification device to indicate that an entry has been deleted. Actual +implementations may take other actions such as physically removing the entry from internal data structures.

               @@ -34882,8 +34882,8 @@ entry from internal data structures.

              23.4.4Properties of WeakSet Instances

              -

              WeakSet instances are ordinary objects that inherit properties -from the WeakSet prototype. WeakSet instances also have a +

              WeakSet instances are ordinary objects that inherit properties +from the WeakSet prototype. WeakSet instances also have a [[WeakSetData]] internal slot.

               @@ -34920,8 +34920,8 @@ from the WeakSet prototype. WeakSet instances also have a Note

              Detaching an ArrayBuffer instance disassociates the Data Block used as its backing store from the instance and sets the byte length of - the buffer to 0. No operations defined by this specification use the -DetachArrayBuffer abstract operation. However, an ECMAScript + the buffer to 0. No operations defined by this specification use the +DetachArrayBuffer abstract operation. However, an ECMAScript implementation or host environment may define such operations.

               @@ -34944,8 +34944,8 @@ implementation or host environment may define such operations.

              24.1.1.6GetValueFromBuffer ( arrayBuffer, byteIndex, type, isTypedArray, order [ , isLittleEndian ] )

              The abstract operation GetValueFromBuffer takes six parameters, an ArrayBuffer or SharedArrayBuffer arrayBuffer, an integer byteIndex, a String type, a Boolean isTypedArray, a String order, and optionally a Boolean isLittleEndian. This operation performs the following steps:

              1. Assert: IsDetachedBuffer(arrayBuffer) is false.
              2. Assert: There are sufficient bytes in arrayBuffer starting at byteIndex to represent a value of type.
              3. Assert: byteIndex is an integer value ≥ 0.
              4. Let block be arrayBuffer.[[ArrayBufferData]].
              5. Let elementSize be the Number value of the Element Size value specified in Table 59 for Element Type type.
              6. If IsSharedArrayBuffer(arrayBuffer) is true, then
                1. Let execution be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
                2. Let eventList be the [[EventList]] field of the element in execution.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
                3. If isTypedArray is true and type is "Int8", "Uint8", "Int16", "Uint16", "Int32", or "Uint32", let noTear be true; otherwise let noTear be false.
                4. Let rawValue be a List of length elementSize of nondeterministically chosen byte values.
                5. NOTE: In implementations, rawValue - is the result of a non-atomic or atomic read instruction on the -underlying hardware. The nondeterminism is a semantic prescription of + is the result of a non-atomic or atomic read instruction on the +underlying hardware. The nondeterminism is a semantic prescription of the memory model to describe observable behaviour of hardware with weak consistency.
                6. Let readEvent be ReadSharedMemory { [[Order]]: order, [[NoTear]]: noTear, [[Block]]: block, [[ByteIndex]]: byteIndex, [[ElementSize]]: elementSize }.
                7. Append readEvent to eventList.
                8. Append Chosen Value Record { [[Event]]: readEvent, [[ChosenValue]]: rawValue } to execution.[[ChosenValues]].
              7. Else, let rawValue be a List of elementSize containing, in order, the elementSize sequence of bytes starting with block[byteIndex].
              8. If isLittleEndian is not present, set isLittleEndian to the value of the [[LittleEndian]] field of the surrounding agent's Agent Record.
              9. Return RawBytesToNumber(type, rawValue, isLittleEndian).
              @@ -34954,11 +34954,11 @@ the 24.1.1.7NumberToRawBytes ( type, value, isLittleEndian )

              The abstract operation NumberToRawBytes takes three parameters, a String type, a Number value, and a Boolean isLittleEndian. This operation performs the following steps:

              1. If type is "Float32", then
                1. Let rawBytes be a List containing the 4 bytes that are the result of converting value to IEEE 754-2008 binary32 format using “Round to nearest, ties to even” rounding mode. If isLittleEndian is false, the bytes are arranged in big endian order. Otherwise, the bytes are arranged in little endian order. If value is NaN, rawBytes - may be set to any implementation chosen IEEE 754-2008 binary32 format -Not-a-Number encoding. An implementation must always choose the same + may be set to any implementation chosen IEEE 754-2008 binary32 format +Not-a-Number encoding. An implementation must always choose the same encoding for each implementation distinguishable NaN value.
              2. Else if type is "Float64", then
                1. Let rawBytes be a List containing the 8 bytes that are the IEEE 754-2008 binary64 format encoding of value. If isLittleEndian is false, the bytes are arranged in big endian order. Otherwise, the bytes are arranged in little endian order. If value is NaN, rawBytes - may be set to any implementation chosen IEEE 754-2008 binary64 format -Not-a-Number encoding. An implementation must always choose the same + may be set to any implementation chosen IEEE 754-2008 binary64 format +Not-a-Number encoding. An implementation must always choose the same encoding for each implementation distinguishable NaN value.
              3. Else,
                1. Let n be the Number value of the Element Size specified in Table 59 for Element Type type.
                2. Let convOp be the abstract operation named in the Conversion Operation column in Table 59 for Element Type type.
                3. Let intValue be convOp(value).
                4. If intValue ≥ 0, then
                  1. Let rawBytes be a List containing the n-byte binary encoding of intValue. If isLittleEndian is false, the bytes are ordered in big endian order. Otherwise, the bytes are ordered in little endian order.
                5. Else,
                  1. Let rawBytes be a List containing the n-byte binary 2's complement encoding of intValue. If isLittleEndian is false, the bytes are ordered in big endian order. Otherwise, the bytes are ordered in little endian order.
              4. Return rawBytes.
              @@ -34975,7 +34975,7 @@ encoding for each implementation distinguishable NaN value.The abstract operation GetModifySetValueInBuffer takes six parameters, a SharedArrayBuffer arrayBuffer, a nonnegative integer byteIndex, a String type, a Number value, a semantic function op, and optionally a Boolean isLittleEndian. This operation performs the following steps:

              1. Assert: IsSharedArrayBuffer(arrayBuffer) is true.
              2. Assert: There are sufficient bytes in arrayBuffer starting at byteIndex to represent a value of type.
              3. Assert: byteIndex is an integer value ≥ 0.
              4. Assert: Type(value) is Number.
              5. Let block be arrayBuffer.[[ArrayBufferData]].
              6. Let elementSize be the Number value of the Element Size value specified in Table 59 for Element Type type.
              7. If isLittleEndian is not present, set isLittleEndian to the value of the [[LittleEndian]] field of the surrounding agent's Agent Record.
              8. Let rawBytes be NumberToRawBytes(type, value, isLittleEndian).
              9. Let execution be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
              10. Let eventList be the [[EventList]] field of the element in execution.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
              11. Let rawBytesRead be a List of length elementSize of nondeterministically chosen byte values.
              12. NOTE: In implementations, rawBytesRead is the result of a load-link, of a load-exclusive, or of an operand of a - read-modify-write instruction on the underlying hardware. The + read-modify-write instruction on the underlying hardware. The nondeterminism is a semantic prescription of the memory model to describe observable behaviour of hardware with weak consistency.
              13. Let rmwEvent be ReadModifyWriteSharedMemory { [[Order]]: "SeqCst", [[NoTear]]: true, [[Block]]: block, [[ByteIndex]]: byteIndex, [[ElementSize]]: elementSize, [[Payload]]: rawBytes, [[ModifyOp]]: op }.
              14. Append rmwEvent to eventList.
              15. Append Chosen Value Record { [[Event]]: rmwEvent, [[ChosenValue]]: rawBytesRead } to execution.[[ChosenValues]].
              16. Return RawBytesToNumber(type, rawBytesRead, isLittleEndian).
              @@ -35071,14 +35071,14 @@ nondeterminism is a semantic prescription of the

              24.1.5Properties of ArrayBuffer Instances

              -

              ArrayBuffer instances inherit properties from the ArrayBuffer +

              ArrayBuffer instances inherit properties from the ArrayBuffer prototype object. ArrayBuffer instances each have an [[ArrayBufferData]] - internal slot, an [[ArrayBufferByteLength]] internal slot, and an + internal slot, an [[ArrayBufferByteLength]] internal slot, and an [[ArrayBufferDetachKey]] internal slot.

              ArrayBuffer instances whose [[ArrayBufferData]] is null are considered to be detached and all operators to access or modify data contained in the ArrayBuffer instance will fail.

              ArrayBuffer instances whose [[ArrayBufferDetachKey]] is set to a value other than undefined need to have all DetachArrayBuffer - calls passing that same "detach key" as an argument, otherwise a -TypeError will result. This internal slot is only ever set by certain + calls passing that same "detach key" as an argument, otherwise a +TypeError will result. This internal slot is only ever set by certain embedding environments, not by algorithms in this specification.

              @@ -35098,8 +35098,8 @@ embedding environments, not by algorithms in this specification.

              24.2.1.2IsSharedArrayBuffer ( obj )

              -

              IsSharedArrayBuffer tests whether an object is an -ArrayBuffer, a SharedArrayBuffer, or a subtype of either. It performs +

              IsSharedArrayBuffer tests whether an object is an +ArrayBuffer, a SharedArrayBuffer, or a subtype of either. It performs the following steps:

              1. Assert: Type(obj) is Object and it has an [[ArrayBufferData]] internal slot.
              2. Let bufferData be obj.[[ArrayBufferData]].
              3. If bufferData is null, return false.
              4. If bufferData is a Data Block, return false.
              5. Assert: bufferData is a Shared Data Block.
              6. Return true.
              @@ -35190,9 +35190,9 @@ the following steps:

              24.2.5Properties of SharedArrayBuffer Instances

              -

              SharedArrayBuffer instances inherit properties from the -SharedArrayBuffer prototype object. SharedArrayBuffer instances each -have an [[ArrayBufferData]] internal slot and an +

              SharedArrayBuffer instances inherit properties from the +SharedArrayBuffer prototype object. SharedArrayBuffer instances each +have an [[ArrayBufferData]] internal slot and an [[ArrayBufferByteLength]] internal slot.

              Note
              @@ -35414,12 +35414,12 @@ have an [[ArrayBufferData]] internal slot and an

              24.3.5Properties of DataView Instances

              DataView instances are ordinary objects that inherit properties - from the DataView prototype object. DataView instances each have -[[DataView]], [[ViewedArrayBuffer]], [[ByteLength]], and [[ByteOffset]] + from the DataView prototype object. DataView instances each have +[[DataView]], [[ViewedArrayBuffer]], [[ByteLength]], and [[ByteOffset]] internal slots.

              Note
              -

              The value of the [[DataView]] internal slot is not used -within this specification. The simple presence of that internal slot is +

              The value of the [[DataView]] internal slot is not used +within this specification. The simple presence of that internal slot is used within the specification to identify objects created using the DataView constructor.

                             @@ -35436,12 +35436,12 @@ used within the specification to identify objects created using the DataVi
            18. does not have a [[Construct]] internal method; it cannot be used as a constructor with the new operator.
            19. does not have a [[Call]] internal method; it cannot be invoked as a function.
      -

      The Atomics object provides functions that operate indivisibly -(atomically) on shared memory array cells as well as functions that let -agents wait for and dispatch primitive events. When used with +

      The Atomics object provides functions that operate indivisibly +(atomically) on shared memory array cells as well as functions that let +agents wait for and dispatch primitive events. When used with discipline, the Atomics functions allow multi-agent - programs that communicate through shared memory to execute in a -well-understood order even on parallel CPUs. The rules that govern + programs that communicate through shared memory to execute in a +well-understood order even on parallel CPUs. The rules that govern shared-memory communication are provided by the memory model, defined below.

      Note

      For informative guidelines for programming and implementing shared memory in ECMAScript, please see the notes at the end of the memory model section.

      @@ -35468,9 +35468,9 @@ shared-memory communication are provided by the 24.4.1.3GetWaiterList ( block, i )

      A WaiterList is a semantic object that contains an ordered list of those agents that are waiting on a location (block, i) in shared memory; block is a Shared Data Block and i a byte offset into the memory of block.

      The agent cluster has a store of WaiterList objects; the store is indexed by (block, i). WaiterLists are agent-independent: a lookup in the store of WaiterLists by (block, i) will result in the same WaiterList object in any agent in the agent cluster.

      -

      Operations on a WaiterList -- adding and removing waiting -agents, traversing the list of agents, suspending and notifying agents -on the list -- may only be performed by agents that have entered the +

      Operations on a WaiterList -- adding and removing waiting +agents, traversing the list of agents, suspending and notifying agents +on the list -- may only be performed by agents that have entered the WaiterList's critical section.

      The abstract operation GetWaiterList takes two arguments, a Shared Data Block block and a nonnegative integer i. It performs the following steps:

      1. Assert: block is a Shared Data Block.
      2. Assert: i and i + 3 are valid byte offsets within the memory of block.
      3. Assert: i is divisible by 4.
      4. Return the WaiterList that is referenced by the pair (block, i). @@ -35516,8 +35516,8 @@ WaiterList's critical section.

        24.4.1.9Suspend ( WL, W, timeout )

        The abstract operation Suspend takes three arguments, a WaiterList WL, an agent signifier W, and a nonnegative, non-NaN Number timeout. It performs the following steps:

        1. Assert: The calling agent is in the critical section for WL.
        2. Assert: W is equal to AgentSignifier().
        3. Assert: W is on the list of waiters in WL.
        4. Assert: AgentCanSuspend() is true.
        5. Perform LeaveCriticalSection(WL) and suspend W for up to timeout - milliseconds, performing the combined operation in such a way that a -notification that arrives after the critical section is exited but + milliseconds, performing the combined operation in such a way that a +notification that arrives after the critical section is exited but before the suspension takes effect is not lost. W can notify either because the timeout expired or because it was notified explicitly by another agent calling NotifyWaiter(WL, W), and not for any other reasons at all.
        6. Perform EnterCriticalSection(WL).
        7. If W was notified explicitly by another agent calling NotifyWaiter(WL, W), return true.
        8. Return false.
        @@ -35535,7 +35535,7 @@ before the suspension takes effect is not lost. W can notify either

        24.4.1.11AtomicReadModifyWrite ( typedArray, index, value, op )

        The abstract operation AtomicReadModifyWrite takes four arguments, typedArray, index, value, and a pure combining operation op. The pure combining operation op takes two List of byte values arguments and returns a List - of byte values. The operation atomically loads a value, combines it + of byte values. The operation atomically loads a value, combines it with another value, and stores the result of the combination. It returns the loaded value. It performs the following steps:

        1. Let buffer be ? ValidateSharedIntegerTypedArray(typedArray).
        2. Let i be ? ValidateAtomicAccess(typedArray, index).
        3. Let v be ? ToInteger(value).
        4. Let arrayTypeName be typedArray.[[TypedArrayName]].
        5. Let elementSize be the Number value of the Element Size value specified in Table 59 for arrayTypeName.
        6. Let elementType be the String value of the Element Type value in Table 59 for arrayTypeName.
        7. Let offset be typedArray.[[ByteOffset]].
        8. Let indexedPosition be (i × elementSize) + offset.
        9. Return GetModifySetValueInBuffer(buffer, indexedPosition, elementType, v, op). @@ -35588,8 +35588,8 @@ with another value, and stores the result of the combination. It returns
        Note

        Atomics.isLockFree() is an optimization primitive. The intuition is that if the atomic step of an atomic primitive (compareExchange, load, store, add, sub, and, or, xor, or exchange) on a datum of size n bytes will be performed without the calling agent acquiring a lock outside the n bytes comprising the datum, then Atomics.isLockFree(n) will return true. - High-performance algorithms will use Atomics.isLockFree to determine -whether to use locks or atomic operations in critical sections. If an + High-performance algorithms will use Atomics.isLockFree to determine +whether to use locks or atomic operations in critical sections. If an atomic primitive is not lock-free then it is often more efficient for an algorithm to provide its own locking.

        Atomics.isLockFree(4) always returns true as that can be supported on all known relevant hardware. Being able to assume this will generally simplify programs.

        @@ -35669,21 +35669,21 @@ atomic primitive is not lock-free then it is often more efficient for an

        The JSON Data Interchange Format is defined in ECMA-404. The JSON interchange format used in this specification is exactly that described by ECMA-404. Conforming implementations of JSON.parse and JSON.stringify - must support the exact interchange format described in the ECMA-404 + must support the exact interchange format described in the ECMA-404 specification without any deletions or extensions to the format.

        24.5.1JSON.parse ( text [ , reviver ] )

        -

        The parse function parses a JSON text (a +

        The parse function parses a JSON text (a JSON-formatted String) and produces an ECMAScript value. The JSON format - represents literals, arrays, and objects with a syntax similar to the -syntax for ECMAScript literals, Array Initializers, and Object -Initializers. After parsing, JSON objects are realized as ECMAScript -objects. JSON arrays are realized as ECMAScript Array instances. JSON + represents literals, arrays, and objects with a syntax similar to the +syntax for ECMAScript literals, Array Initializers, and Object +Initializers. After parsing, JSON objects are realized as ECMAScript +objects. JSON arrays are realized as ECMAScript Array instances. JSON strings, numbers, booleans, and null are realized as ECMAScript Strings, Numbers, Booleans, and null.

        The optional reviver parameter is a function that takes two parameters, key and value. It can filter and transform the results. It is called with each of the key/value - pairs produced by the parse, and its return value is used instead of + pairs produced by the parse, and its return value is used instead of the original value. If it returns what it received, the structure is not modified. If it returns undefined then the property is deleted from the result.

        1. Let JText be ? ToString(text).
        2. Parse JText interpreted as UTF-16 encoded Unicode points (6.1.4) as a JSON text as specified in ECMA-404. Throw a SyntaxError exception if JText is not a valid JSON text as defined in that specification.
        3. Let scriptText be the string-concatenation of "(", JText, and ");".
        4. Let completion be the result of parsing and evaluating scriptText as if it was the source text of an ECMAScript Script. The extended PropertyDefinitionEvaluation semantics defined in B.3.1 must not be used during the evaluation.
        5. Let unfiltered be completion.[[Value]].
        6. Assert: unfiltered is either a String, Number, Boolean, Null, or an Object that is defined by either an ArrayLiteral or an ObjectLiteral.
        7. If IsCallable(reviver) is true, then
          1. Let root be ObjectCreate(%ObjectPrototype%).
          2. Let rootName be the empty String.
          3. Let status be CreateDataProperty(root, rootName, unfiltered).
          4. Assert: status is true.
          5. Return ? InternalizeJSONProperty(root, rootName).
        8. Else,
          1. Return unfiltered. @@ -35700,12 +35700,12 @@ the original value. If it returns what it received, the structure is not
            1. Let val be ? Get(holder, name).
            2. If Type(val) is Object, then
              1. Let isArray be ? IsArray(val).
              2. If isArray is true, then
                1. Let I be 0.
                2. Let len be ? ToLength(? Get(val, "length")).
                3. Repeat, while I < len,
                  1. Let newElement be ? InternalizeJSONProperty(val, ! ToString(I)).
                  2. If newElement is undefined, then
                    1. Perform ? val.[[Delete]](! ToString(I)).
                  3. Else,
                    1. Perform ? CreateDataProperty(val, ! ToString(I), newElement).
                    2. NOTE: This algorithm intentionally does not throw an exception if CreateDataProperty returns false.
                  4. Add 1 to I.
              3. Else,
                1. Let keys be ? EnumerableOwnPropertyNames(val, "key").
                2. For each String P in keys, do
                  1. Let newElement be ? InternalizeJSONProperty(val, P).
                  2. If newElement is undefined, then
                    1. Perform ? val.[[Delete]](P).
                  3. Else,
                    1. Perform ? CreateDataProperty(val, P, newElement).
                    2. NOTE: This algorithm intentionally does not throw an exception if CreateDataProperty returns false.
            3. Return ? Call(reviver, holder, « name, val »).

            It is not permitted for a conforming implementation of JSON.parse - to extend the JSON grammars. If an implementation wishes to support a + to extend the JSON grammars. If an implementation wishes to support a modified or extended JSON interchange format it must do so by defining a different parse function.

            Note
            -

            In the case where there are duplicate name Strings within -an object, lexically preceding values for the same key shall be +

            In the case where there are duplicate name Strings within +an object, lexically preceding values for the same key shall be overwritten.

             @@ -35714,9 +35714,9 @@ overwritten.

            24.5.2JSON.stringify ( value [ , replacer [ , space ] ] )

            The stringify function returns a String in UTF-16 encoded JSON format representing an ECMAScript value, or undefined. It can take three parameters. The value parameter is an ECMAScript value, which is usually an object or array, although it can also be a String, Boolean, Number or null. The optional replacer - parameter is either a function that alters the way objects and arrays -are stringified, or an array of Strings and Numbers that acts as an -inclusion list for selecting the object properties that will be + parameter is either a function that alters the way objects and arrays +are stringified, or an array of Strings and Numbers that acts as an +inclusion list for selecting the object properties that will be stringified. The optional space parameter is a String or Number that allows the result to have white space injected into it to improve human readability.

            These are the steps in stringifying an object:

            1. Let stack be a new empty List.
            2. Let indent be the empty String.
            3. Let PropertyList and ReplacerFunction be undefined.
            4. If Type(replacer) is Object, then
              1. If IsCallable(replacer) is true, then
                1. Set ReplacerFunction to replacer.
              2. Else,
                1. Let isArray be ? IsArray(replacer).
                2. If isArray is true, then
                  1. Set PropertyList to a new empty List.
                  2. Let len be ? ToLength(? Get(replacer, "length")).
                  3. Let k be 0.
                  4. Repeat, while k < len,
                    1. Let v be ? Get(replacer, ! ToString(k)).
                    2. Let item be undefined.
                    3. If Type(v) is String, set item to v.
                    4. Else if Type(v) is Number, set item to ! ToString(v).
                    5. Else if Type(v) is Object, then
                      1. If v has a [[StringData]] or [[NumberData]] internal slot, set item to ? ToString(v).
                    6. If item is not undefined and item is not currently an element of PropertyList, then
                      1. Append item to the end of PropertyList.
                    7. Increase k by 1.
            5. If Type(space) is Object, then
              1. If space has a [[NumberData]] internal slot, then
                1. Set space to ? ToNumber(space).
              2. Else if space has a [[StringData]] internal slot, then
                1. Set space to ? ToString(space).
            6. If Type(space) is Number, then
              1. Set space to min(10, ! ToInteger(space)).
              2. Let gap be the String value containing space occurrences of the code unit 0x0020 (SPACE). This will be the empty String if space is less than 1.
            7. Else if Type(space) is String, then
              1. If the length of space is 10 or less, let gap be space; otherwise let gap be the String value consisting of the first 10 code units of space.
            8. Else,
              1. Let gap be the empty String.
            9. Let wrapper be ObjectCreate(%ObjectPrototype%).
            10. Let status be CreateDataProperty(wrapper, the empty String, value).
            11. Assert: status is true.
            12. Return ? SerializeJSONProperty(the empty String, wrapper). @@ -35733,19 +35733,19 @@ my_text = JSON.stringify(a); JSON.stringify(a); Note 6

              An object is rendered as U+007B (LEFT CURLY BRACKET) followed - by zero or more properties, separated with a U+002C (COMMA), closed -with a U+007D (RIGHT CURLY BRACKET). A property is a quoted String + by zero or more properties, separated with a U+002C (COMMA), closed +with a U+007D (RIGHT CURLY BRACKET). A property is a quoted String representing the key or property name, - a U+003A (COLON), and then the stringified property value. An array is -rendered as an opening U+005B (LEFT SQUARE BRACKET followed by zero or -more values, separated with a U+002C (COMMA), closed with a U+005D + a U+003A (COLON), and then the stringified property value. An array is +rendered as an opening U+005B (LEFT SQUARE BRACKET followed by zero or +more values, separated with a U+002C (COMMA), closed with a U+005D (RIGHT SQUARE BRACKET).

              @@ -35788,113 +35788,113 @@ more values, separated with a U+002C (COMMA), closed with a U+005D Code Point - + Unicode Character Name - + Escape Sequence - + U+0008 - + BACKSPACE - + \b - + U+0009 - + CHARACTER TABULATION - + \t - + U+000A - + LINE FEED (LF) - + \n - + U+000C - + FORM FEED (FF) - + \f - + U+000D - + CARRIAGE RETURN (CR) - + \r - + U+0022 - + QUOTATION MARK - + \" - + U+005C - + REVERSE SOLIDUS - + \\ - + @@ -35913,7 +35913,7 @@ more values, separated with a U+002C (COMMA), closed with a U+005D

              24.5.2.4Runtime Semantics: SerializeJSONObject ( value )

              The abstract operation SerializeJSONObject with argument value serializes an object. It has access to the stack, indent, gap, and PropertyList values of the current invocation of the stringify method.

              1. If stack contains value, throw a TypeError exception because the structure is cyclical.
              2. Append value to stack.
              3. Let stepback be indent.
              4. Set indent to the string-concatenation of indent and gap.
              5. If PropertyList is not undefined, then
                1. Let K be PropertyList.
              6. Else,
                1. Let K be ? EnumerableOwnPropertyNames(value, "key").
              7. Let partial be a new empty List.
              8. For each element P of K, do
                1. Let strP be ? SerializeJSONProperty(P, value).
                2. If strP is not undefined, then
                  1. Let member be QuoteJSONString(P).
                  2. Set member to the string-concatenation of member and ":".
                  3. If gap is not the empty String, then
                    1. Set member to the string-concatenation of member and the code unit 0x0020 (SPACE).
                  4. Set member to the string-concatenation of member and strP.
                  5. Append member to partial.
              9. If partial is empty, then
                1. Let final be "{}".
              10. Else,
                1. If gap is the empty String, then
                  1. Let properties be the String value formed by concatenating all the element Strings of partial - with each adjacent pair of Strings separated with the code unit 0x002C + with each adjacent pair of Strings separated with the code unit 0x002C (COMMA). A comma is not inserted either before the first String or after the last String.
                  2. Let final be the string-concatenation of "{", properties, and "}".
                2. Else gap is not the empty String,
                  1. Let separator be the string-concatenation of the code unit 0x002C (COMMA), the code unit 0x000A (LINE FEED), and indent.
                  2. Let properties be the String value formed by concatenating all the element Strings of partial with each adjacent pair of Strings separated with separator. The separator String is not inserted either before the first String or after the last String.
                  3. Let final be the string-concatenation of "{", the code unit 0x000A (LINE FEED), indent, properties, the code unit 0x000A (LINE FEED), stepback, and "}".
              11. Remove the last element of stack.
              12. Set indent to stepback.
              13. Return final.
              @@ -35923,14 +35923,14 @@ more values, separated with a U+002C (COMMA), closed with a U+005D

              24.5.2.5Runtime Semantics: SerializeJSONArray ( value )

              The abstract operation SerializeJSONArray with argument value serializes an array. It has access to the stack, indent, and gap values of the current invocation of the stringify method.

              1. If stack contains value, throw a TypeError exception because the structure is cyclical.
              2. Append value to stack.
              3. Let stepback be indent.
              4. Set indent to the string-concatenation of indent and gap.
              5. Let partial be a new empty List.
              6. Let len be ? ToLength(? Get(value, "length")).
              7. Let index be 0.
              8. Repeat, while index < len
                1. Let strP be ? SerializeJSONProperty(! ToString(index), value).
                2. If strP is undefined, then
                  1. Append "null" to partial.
                3. Else,
                  1. Append strP to partial.
                4. Increment index by 1.
              9. If partial is empty, then
                1. Let final be "[]".
              10. Else,
                1. If gap is the empty String, then
                  1. Let properties be the String value formed by concatenating all the element Strings of partial - with each adjacent pair of Strings separated with the code unit 0x002C + with each adjacent pair of Strings separated with the code unit 0x002C (COMMA). A comma is not inserted either before the first String or after the last String.
                  2. Let final be the string-concatenation of "[", properties, and "]".
                2. Else,
                  1. Let separator be the string-concatenation of the code unit 0x002C (COMMA), the code unit 0x000A (LINE FEED), and indent.
                  2. Let properties be the String value formed by concatenating all the element Strings of partial with each adjacent pair of Strings separated with separator. The separator String is not inserted either before the first String or after the last String.
                  3. Let final be the string-concatenation of "[", the code unit 0x000A (LINE FEED), indent, properties, the code unit 0x000A (LINE FEED), stepback, and "]".
              11. Remove the last element of stack.
              12. Set indent to stepback.
              13. Return final.
              Note

              The representation of arrays includes only the elements between zero and array.length - 1 inclusive. Properties whose keys are not array indexes - are excluded from the stringification. An array is stringified as an -opening LEFT SQUARE BRACKET, elements separated by COMMA, and a closing + are excluded from the stringification. An array is stringified as an +opening LEFT SQUARE BRACKET, elements separated by COMMA, and a closing RIGHT SQUARE BRACKET.

               @@ -35952,10 +35952,10 @@ RIGHT SQUARE BRACKET.

              25.1.1Common Iteration Interfaces

              -

              An interface is a set of property keys whose associated values -match a specific specification. Any object that provides all the +

              An interface is a set of property keys whose associated values +match a specific specification. Any object that provides all the properties as described by an interface's specification conforms - to that interface. An interface is not represented by a distinct + to that interface. An interface is not represented by a distinct object. There may be many separately implemented objects that conform to any interface. An individual object may conform to multiple interfaces.

              @@ -35968,29 +35968,29 @@ object. There may be many separately implemented objects that conform to Property - + Value - + Requirements - + @@iterator - + A function that returns an Iterator object. - + The returned object must conform to the Iterator interface. - + @@ -36007,29 +36007,29 @@ object. There may be many separately implemented objects that conform to Property - + Value - + Requirements - + next - + A function that returns an IteratorResult object. - + The returned object must conform to the IteratorResult interface. If a previous call to the next method of an Iterator has returned an IteratorResult object whose done property is true, then all subsequent calls to the next method of that object should also return an IteratorResult object whose done property is true. However, this requirement is not enforced. - + @@ -36044,56 +36044,56 @@ object. There may be many separately implemented objects that conform to Property - + Value - + Requirements - + return - + A function that returns an IteratorResult object. - + The returned object must conform to the IteratorResult interface. Invoking this method notifies the Iterator object that the caller does not intend to make any more next method calls to the Iterator. The returned IteratorResult object will typically have a done property whose value is true, and a value property with the value passed as the argument of the return method. However, this requirement is not enforced. - + throw - + A function that returns an IteratorResult object. - + The returned object must conform to the IteratorResult interface. Invoking this method notifies the Iterator - object that the caller has detected an error condition. The argument -may be used to identify the error condition and typically will be an + object that the caller has detected an error condition. The argument +may be used to identify the error condition and typically will be an exception object. A typical response is to throw the value passed as the argument. If the method does not throw, the returned IteratorResult object will typically have a done property whose value is true. - + Note 2
              -

              Typically callers of these methods should check for their -existence before invoking them. Certain ECMAScript language features -including for-of, yield*, and -array destructuring call these methods after performing an existence +

              Typically callers of these methods should check for their +existence before invoking them. Certain ECMAScript language features +including for-of, yield*, and +array destructuring call these methods after performing an existence check. Most ECMAScript library functions that accept Iterable objects as arguments also conditionally call them.

                             @@ -36160,9 +36160,9 @@ check. Most ECMAScript library functions that accept Iterable objects as

              The returned promise, when fulfilled, must fulfill with an object which conforms to the IteratorResult interface. Invoking this method notifies the AsyncIterator object that the caller does not intend to make any more next method calls to the AsyncIterator. The returned promise will fulfill with an IteratorResult object which will typically have a done property whose value is true, and a value property with the value passed as the argument of the return method. However, this requirement is not enforced.

              Additionally, the IteratorResult object that serves as a fulfillment value should have a value - property whose value is not a promise (or "thenable"). If the argument + property whose value is not a promise (or "thenable"). If the argument value is used in the typical manner, then if it is a rejected promise, a - promise rejected with the same reason should be returned; if it is a + promise rejected with the same reason should be returned; if it is a fulfilled promise, then its fulfillment value should be used as the value property of the returned promise's IteratorResult object fulfillment value. However, these requirements are also not enforced.

              @@ -36171,9 +36171,9 @@ fulfilled promise, then its fulfillment value should be used as the value< A function that returns a promise for an IteratorResult object.

              The returned promise, when fulfilled, must fulfill with an object which conforms to the IteratorResult interface. Invoking this method notifies the AsyncIterator - object that the caller has detected an error condition. The argument -may be used to identify the error condition and typically will be an -exception object. A typical response is to return a rejected promise + object that the caller has detected an error condition. The argument +may be used to identify the error condition and typically will be an +exception object. A typical response is to return a rejected promise which rejects with the value passed as the argument.

              If the returned promise is fulfilled, the IteratorResult fulfillment value will typically have a done property whose value is true. Additionally, it should have a value property whose value is not a promise (or "thenable"), but this requirement is not enforced.

              @@ -36183,8 +36183,8 @@ which rejects with the value passed as the argument.

              Note 2
              -

              Typically callers of these methods should check for their -existence before invoking them. Certain ECMAScript language features +

              Typically callers of these methods should check for their +existence before invoking them. Certain ECMAScript language features including for-await-of and yield* call these methods after performing an existence check.

               @@ -36198,43 +36198,43 @@ including for-await-of and yield* Property - + Value - + Requirements - + done - + Either true or false. - + This is the result status of an iterator next method call. If the end of the iterator was reached done is true. If the end was not reached done is false and a value is available. If a done property (either own or inherited) does not exist, it is consider to have the value false. - + value - + Any ECMAScript language value. - + If done is false, this is the current iteration element value. If done is true, this is the return value of the iterator, if it supplied one. If the iterator does not have a return value, value is undefined. In that case, the value property may be absent from the conforming object if it does not inherit an explicit value property. - + @@ -36251,10 +36251,10 @@ including for-await-of and yield*is an ordinary object.
              13. Note
              -

              All objects defined in this specification that implement the -Iterator interface also inherit from %IteratorPrototype%. ECMAScript -code may also define objects that inherit from %IteratorPrototype%.The -%IteratorPrototype% object provides a place where additional methods +

              All objects defined in this specification that implement the +Iterator interface also inherit from %IteratorPrototype%. ECMAScript +code may also define objects that inherit from %IteratorPrototype%.The +%IteratorPrototype% object provides a place where additional methods that are applicable to all iterator objects may be added.

              The following expression is one way that ECMAScript code can access the %IteratorPrototype% object:

              Object.getPrototypeOf(Object.getPrototypeOf([][Symbol.iterator]()))
              @@ -36277,10 +36277,10 @@ that are applicable to all iterator objects may be added.

            13. is an ordinary object.
              14. Note
              -

              All objects defined in this specification that implement the -AsyncIterator interface also inherit from %AsyncIteratorPrototype%. -ECMAScript code may also define objects that inherit from -%AsyncIteratorPrototype%.The %AsyncIteratorPrototype% object provides a +

              All objects defined in this specification that implement the +AsyncIterator interface also inherit from %AsyncIteratorPrototype%. +ECMAScript code may also define objects that inherit from +%AsyncIteratorPrototype%.The %AsyncIteratorPrototype% object provides a place where additional methods that are applicable to all async iterator objects may be added.

               @@ -36362,11 +36362,11 @@ place where additional methods that are applicable to all async iterator Internal Slot - + Description - + @@ -36374,11 +36374,11 @@ place where additional methods that are applicable to all async iterator [[SyncIteratorRecord]] - + A Record, of the type returned by GetIterator, representing the original synchronous iterator which is being adapted. - + @@ -36409,15 +36409,15 @@ place where additional methods that are applicable to all async iterator
            14. is the intrinsic object %GeneratorFunction%.
            15. creates and initializes a new GeneratorFunction object when called as a function rather than as a constructor. Thus the function call GeneratorFunction (…) is equivalent to the object creation expression new GeneratorFunction (…) with the same arguments.
            16. is designed to be subclassable. It may be used as the value of an extends clause of a class definition. Subclass constructors that intend to inherit the specified GeneratorFunction behaviour must include a super call to the GeneratorFunction constructor - to create and initialize subclass instances with the internal slots -necessary for built-in GeneratorFunction behaviour. All ECMAScript -syntactic forms for defining generator function objects create direct + to create and initialize subclass instances with the internal slots +necessary for built-in GeneratorFunction behaviour. All ECMAScript +syntactic forms for defining generator function objects create direct instances of GeneratorFunction. There is no syntactic means to create instances of GeneratorFunction subclasses.

              17. 25.2.1.1GeneratorFunction ( p1, p2, … , pn, body )

              -

              The last argument specifies the body (executable code) of a +

              The last argument specifies the body (executable code) of a generator function; any preceding arguments specify formal parameters.

              When the GeneratorFunction function is called with some arguments p1, p2, … , pn, body (where n might be 0, that is, there are no “p” arguments, and where body might also not be provided), the following steps are taken:

              1. Let C be the active function object.
              2. Let args be the argumentsList that was passed to this function by [[Call]] or [[Construct]].
              3. Return ? CreateDynamicFunction(C, NewTarget, "generator", args). @@ -36497,9 +36497,9 @@ generator function; any preceding arguments specify formal parameters.

                25.2.4.3prototype

                -

                Whenever a GeneratorFunction instance is created another -ordinary object is also created and is the initial value of the -generator function's prototype property. The value of the +

                Whenever a GeneratorFunction instance is created another +ordinary object is also created and is the initial value of the +generator function's prototype property. The value of the prototype property is used to initialize the [[Prototype]] internal slot of a newly created Generator object when the generator function object is invoked using [[Call]].

                This property has the attributes { [[Writable]]: true, [[Enumerable]]: false, [[Configurable]]: false }.

                @@ -36521,16 +36521,16 @@ prototype property is used to initialize the [[Prototype]] internal slot
              4. is the intrinsic object %AsyncGeneratorFunction%.
              5. creates and initializes a new AsyncGeneratorFunction object when called as a function rather than as a constructor. Thus the function call AsyncGeneratorFunction (...) is equivalent to the object creation expression new AsyncGeneratorFunction (...) with the same arguments.
              6. is designed to be subclassable. It may be used as the value of an extends clause of a class definition. Subclass constructors that intend to inherit the specified AsyncGeneratorFunction behaviour must include a super call to the AsyncGeneratorFunction constructor - to create and initialize subclass instances with the internal slots -necessary for built-in AsyncGeneratorFunction behaviour. All ECMAScript -syntactic forms for defining async generator function objects create + to create and initialize subclass instances with the internal slots +necessary for built-in AsyncGeneratorFunction behaviour. All ECMAScript +syntactic forms for defining async generator function objects create direct instances of AsyncGeneratorFunction. There is no syntactic means to create instances of AsyncGeneratorFunction subclasses.

                7. 25.3.1.1AsyncGeneratorFunction ( p1, p2, ..., pn, body )

                -

                The last argument specifies the body (executable code) of an -async generator function; any preceding arguments specify formal +

                The last argument specifies the body (executable code) of an +async generator function; any preceding arguments specify formal parameters.

                When the AsyncGeneratorFunction function is called with some arguments p1, p2, … , pn, body (where n might be 0, that is, there are no "p" arguments, and where body might also not be provided), the following steps are taken:

                1. Let C be the active function object.
                2. Let args be the argumentsList that was passed to this function by [[Call]] or [[Construct]].
                3. Return ? CreateDynamicFunction(C, NewTarget, "async generator", args). @@ -36601,10 +36601,10 @@ parameters.

                  25.3.4.1length

                  The value of the "length" property is an integer - that indicates the typical number of arguments expected by the + that indicates the typical number of arguments expected by the AsyncGeneratorFunction. However, the language permits the function to be - invoked with some other number of arguments. The behaviour of an -AsyncGeneratorFunction when invoked on a number of arguments other than + invoked with some other number of arguments. The behaviour of an +AsyncGeneratorFunction when invoked on a number of arguments other than the number specified by its "length" property depends on the function.

                  This property has the attributes { [[Writable]]: false, [[Enumerable]]: false, [[Configurable]]: true }.

                   @@ -36616,8 +36616,8 @@ the number specified by its "length" property depends on the functi

                  25.3.4.3prototype

                  -

                  Whenever an AsyncGeneratorFunction instance is created -another ordinary object is also created and is the initial value of the +

                  Whenever an AsyncGeneratorFunction instance is created +another ordinary object is also created and is the initial value of the async generator function's prototype property. The value of the prototype property is used to initialize the [[Prototype]] internal slot of a newly created AsyncGenerator object when the generator function object is invoked using [[Call]].

                  @@ -36634,7 +36634,7 @@ async generator function's prototype property. The value of

                  A Generator object is an instance of a generator function and conforms to both the Iterator and Iterable interfaces.

                  Generator instances directly inherit properties from the object that is the value of the prototype property of the Generator function that created the instance. Generator - instances indirectly inherit properties from the Generator Prototype + instances indirectly inherit properties from the Generator Prototype intrinsic, %GeneratorPrototype%.

                  @@ -36692,31 +36692,31 @@ intrinsic, , "suspendedYield", "executing", and "completed". - + [[GeneratorContext]] - + The execution context that is used when executing the code of this generator. - + @@ -36772,13 +36772,13 @@ intrinsic,

                  25.5AsyncGenerator Objects

                  -

                  An AsyncGenerator object is an instance of an async generator -function and conforms to both the AsyncIterator and AsyncIterable +

                  An AsyncGenerator object is an instance of an async generator +function and conforms to both the AsyncIterator and AsyncIterable interfaces.

                  AsyncGenerator instances directly inherit properties from the object that is the value of the prototype - property of the AsyncGenerator function that created the instance. -AsyncGenerator instances indirectly inherit properties from the + property of the AsyncGenerator function that created the instance. +AsyncGenerator instances indirectly inherit properties from the AsyncGenerator Prototype intrinsic, %AsyncGeneratorPrototype%.

                  @@ -36857,8 +36857,8 @@ AsyncGenerator Prototype intrinsic,

                  25.5.3.1AsyncGeneratorRequest Records

                  The AsyncGeneratorRequest is a Record - value used to store information about how an async generator should be -resumed and contains capabilities for fulfilling or rejecting the + value used to store information about how an async generator should be +resumed and contains capabilities for fulfilling or rejecting the corresponding promise.

                  They have the following fields:

                  Table 73: AsyncGeneratorRequest Record Fields
                  @@ -36951,28 +36951,28 @@ corresponding promise.

                  25.6Promise Objects

                  -

                  A Promise is an object that is used as a placeholder for the +

                  A Promise is an object that is used as a placeholder for the eventual results of a deferred (and possibly asynchronous) computation.

                  Any Promise object is in one of three mutually exclusive states: fulfilled, rejected, and pending:

                  • A promise p is fulfilled if p.then(f, r) will immediately enqueue a Job to call the function f. - +
                  • A promise p is rejected if p.then(f, r) will immediately enqueue a Job to call the function r. - +
                  • A promise is pending if it is neither fulfilled nor rejected. - +

                  A promise is said to be settled if it is not pending, i.e. if it is either fulfilled or rejected.

                  -

                  A promise is resolved if it is settled or if it has -been “locked in” to match the state of another promise. Attempting to +

                  A promise is resolved if it is settled or if it has +been “locked in” to match the state of another promise. Attempting to resolve or reject a resolved promise has no effect. A promise is unresolved - if it is not resolved. An unresolved promise is always in the pending + if it is not resolved. An unresolved promise is always in the pending state. A resolved promise may be pending, fulfilled or rejected.

                  @@ -36981,8 +36981,8 @@ state. A resolved promise may be pending, fulfilled or rejected.

                  25.6.1.1PromiseCapability Records

                  A PromiseCapability is a Record - value used to encapsulate a promise object along with the functions -that are capable of resolving or rejecting that promise object. + value used to encapsulate a promise object along with the functions +that are capable of resolving or rejecting that promise object. PromiseCapability Records are produced by the NewPromiseCapability abstract operation.

                  PromiseCapability Records have the fields listed in Table 74.

                  Table 74: PromiseCapability Record Fields
                  @@ -36991,57 +36991,57 @@ PromiseCapability Records are produced by the function object - + The function that is used to resolve the given promise object. - + [[Reject]] - + A function object - + The function that is used to reject the given promise object. - + @@ -37062,8 +37062,8 @@ PromiseCapability Records are produced by the

                  25.6.1.2PromiseReaction Records

                  The PromiseReaction is a Record - value used to store information about how a promise should react when -it becomes resolved or rejected with a given value. PromiseReaction + value used to store information about how a promise should react when +it becomes resolved or rejected with a given value. PromiseReaction records are created by the PerformPromiseThen abstract operation, and are used by a PromiseReactionJob.

                  PromiseReaction records have the fields listed in Table 75.

                  Table 75: PromiseReaction Record Fields
                  @@ -37072,59 +37072,59 @@ records are created by the Field Name - + Value - + Meaning - + [[Capability]] - + A PromiseCapability Record, or undefined - + The capabilities of the promise for which this record provides a reaction handler. - + [[Type]] - + Either "Fulfill" or "Reject". - + The [[Type]] is used when [[Handler]] is undefined to allow for behaviour specific to the settlement type. - + [[Handler]] - + A function object or undefined. - + - The function that should be applied to the incoming -value, and whose return value will govern what happens to the derived + The function that should be applied to the incoming +value, and whose return value will govern what happens to the derived promise. If [[Handler]] is undefined, a function that depends on the value of [[Type]] will be used instead. - + @@ -37167,7 +37167,7 @@ promise. If [[Handler]] is undefined, a function that depends

                  25.6.1.5NewPromiseCapability ( C )

                  The abstract operation NewPromiseCapability takes a constructor function, and attempts to use that constructor function in the fashion of the built-in Promise constructor - to create a Promise object and extract its resolve and reject + to create a Promise object and extract its resolve and reject functions. The promise plus the resolve and reject functions are used to initialize a new PromiseCapability Record which is returned as the value of this abstract operation.

                  1. If IsConstructor(C) is false, throw a TypeError exception.
                  2. NOTE: C is assumed to be a constructor function that supports the parameter conventions of the Promise constructor (see 25.6.3.1).
                  3. Let promiseCapability be a new PromiseCapability { [[Promise]]: undefined, [[Resolve]]: undefined, [[Reject]]: undefined }.
                  4. Let steps be the algorithm steps defined in GetCapabilitiesExecutor Functions.
                  5. Let executor be CreateBuiltinFunction(steps, « [[Capability]] »).
                  6. Set executor.[[Capability]] to promiseCapability.
                  7. Let promise be ? Construct(C, « executor »).
                  8. If IsCallable(promiseCapability.[[Resolve]]) is false, throw a TypeError exception.
                  9. If IsCallable(promiseCapability.[[Reject]]) is false, throw a TypeError exception.
                  10. Set promiseCapability.[[Promise]] to promise.
                  11. Return promiseCapability. @@ -37202,10 +37202,10 @@ functions. The promise plus the resolve and reject functions are used to

                    25.6.1.8TriggerPromiseReactions ( reactions, argument )

                    -

                    The abstract operation TriggerPromiseReactions takes a -collection of PromiseReactionRecords and enqueues a new Job for each -record. Each such Job processes the [[Type]] and [[Handler]] of the -PromiseReactionRecord, and if the [[Handler]] is a function, calls it +

                    The abstract operation TriggerPromiseReactions takes a +collection of PromiseReactionRecords and enqueues a new Job for each +record. Each such Job processes the [[Type]] and [[Handler]] of the +PromiseReactionRecord, and if the [[Handler]] is a function, calls it passing the given argument. If the [[Handler]] is undefined, the behaviour is determined by the [[Type]].

                    1. For each reaction in reactions, in original insertion order, do
                      1. Perform EnqueueJob("PromiseJobs", PromiseReactionJob, « reaction, argument »).
                    2. Return undefined.
                    @@ -37214,12 +37214,12 @@ passing the given argument. If the [[Handler]] is undefined,

                    25.6.1.9HostPromiseRejectionTracker ( promise, operation )

                    -

                    HostPromiseRejectionTracker is an implementation-defined -abstract operation that allows host environments to track promise +

                    HostPromiseRejectionTracker is an implementation-defined +abstract operation that allows host environments to track promise rejections.

                    -

                    An implementation of HostPromiseRejectionTracker must -complete normally in all cases. The default implementation of +

                    An implementation of HostPromiseRejectionTracker must +complete normally in all cases. The default implementation of HostPromiseRejectionTracker is to unconditionally return an empty normal completion.

                    @@ -37231,9 +37231,9 @@ HostPromiseRejectionTracker is to unconditionally return an empty normal
                  12. When a handler is added to a rejected promise for the first time, it is called with its operation argument set to "handle".
                    13. -

                    A typical implementation of HostPromiseRejectionTracker +

                    A typical implementation of HostPromiseRejectionTracker might try to notify developers of unhandled rejections, while also being - careful to notify them if such previous notifications are later + careful to notify them if such previous notifications are later invalidated by new handlers being attached.

               @@ -37249,8 +37249,8 @@ invalidated by new handlers being attached.

              25.6.2.1PromiseReactionJob ( reaction, argument )

              The job PromiseReactionJob with parameters reaction and argument - applies the appropriate handler to the incoming value, and uses the -handler's return value to resolve or reject the derived promise + applies the appropriate handler to the incoming value, and uses the +handler's return value to resolve or reject the derived promise associated with that handler.

              1. Assert: reaction is a PromiseReaction Record.
              2. Let promiseCapability be reaction.[[Capability]].
              3. Let type be reaction.[[Type]].
              4. Let handler be reaction.[[Handler]].
              5. If handler is undefined, then
                1. If type is "Fulfill", let handlerResult be NormalCompletion(argument).
                2. Else,
                  1. Assert: type is "Reject".
                  2. Let handlerResult be ThrowCompletion(argument).
              6. Else, let handlerResult be Call(handler, undefined, « argument »).
              7. If promiseCapability is undefined, then
                1. Assert: handlerResult is not an abrupt completion.
                2. Return NormalCompletion(empty).
              8. If handlerResult is an abrupt completion, then
                1. Let status be Call(promiseCapability.[[Reject]], undefined, « handlerResult.[[Value]] »).
              9. Else,
                1. Let status be Call(promiseCapability.[[Resolve]], undefined, « handlerResult.[[Value]] »).
              10. Return Completion(status).
              @@ -37285,16 +37285,16 @@ associated with that handler.

             Note

            The executor argument must be a function object. - It is called for initiating and reporting completion of the possibly -deferred action represented by this Promise object. The executor is + It is called for initiating and reporting completion of the possibly +deferred action represented by this Promise object. The executor is called with two arguments: resolve and reject. These are functions that may be used by the executor - function to report eventual completion or failure of the deferred + function to report eventual completion or failure of the deferred computation. Returning from the executor function does not mean that the - deferred action has been completed but only that the request to + deferred action has been completed but only that the request to eventually perform the deferred action has been accepted.

            The resolve function that is passed to an executor function accepts a single argument. The executor code may eventually call the resolve function to indicate that it wishes to resolve the associated Promise object. The argument passed to the resolve - function represents the eventual value of the deferred action and can -be either the actual fulfillment value or another Promise object which + function represents the eventual value of the deferred action and can +be either the actual fulfillment value or another Promise object which will provide the value if it is fulfilled.

            The reject function that is passed to an executor function accepts a single argument. The executor code may eventually call the reject function to indicate that the associated Promise is rejected and will never be fulfilled. The argument passed to the reject function is used as the rejection value of the promise. Typically it will be an Error object.

            The resolve and reject functions passed to an executor function by the Promise constructor have the capability to actually resolve and reject the associated promise. Subclasses may have different constructor behaviour that passes in customized values for resolve and reject.

            @@ -37312,9 +37312,9 @@ will provide the value if it is fulfilled.

            25.6.4.1Promise.all ( iterable )

            -

            The all function returns a new promise which is -fulfilled with an array of fulfillment values for the passed promises, -or rejects with the reason of the first passed promise that rejects. It +

            The all function returns a new promise which is +fulfilled with an array of fulfillment values for the passed promises, +or rejects with the reason of the first passed promise that rejects. It resolves all elements of the passed iterable to promises as it runs this algorithm.

            1. Let C be the this value.
            2. If Type(C) is not Object, throw a TypeError exception.
            3. Let promiseCapability be ? NewPromiseCapability(C).
            4. Let iteratorRecord be GetIterator(iterable).
            5. IfAbruptRejectPromise(iteratorRecord, promiseCapability).
            6. Let result be PerformPromiseAll(iteratorRecord, C, promiseCapability).
            7. If result is an abrupt completion, then
              1. If iteratorRecord.[[Done]] is false, set result to IteratorClose(iteratorRecord, result).
              2. IfAbruptRejectPromise(result, promiseCapability).
            8. Return Completion(result). @@ -37334,7 +37334,7 @@ resolves all elements of the passed iterable to promises as it runs this

              25.6.4.1.2Promise.all Resolve Element Functions

              A Promise.all resolve element function is an anonymous built-in function that is used to resolve a specific Promise.all element. Each Promise.all - resolve element function has [[Index]], [[Values]], [[Capability]], + resolve element function has [[Index]], [[Values]], [[Capability]], [[RemainingElements]], and [[AlreadyCalled]] internal slots.

              When a Promise.all resolve element function is called with argument x, the following steps are taken:

              1. Let F be the active function object.
              2. Let alreadyCalled be F.[[AlreadyCalled]].
              3. If alreadyCalled.[[Value]] is true, return undefined.
              4. Set alreadyCalled.[[Value]] to true.
              5. Let index be F.[[Index]].
              6. Let values be F.[[Values]].
              7. Let promiseCapability be F.[[Capability]].
              8. Let remainingElementsCount be F.[[RemainingElements]].
              9. Set values[index] to x.
              10. Set remainingElementsCount.[[Value]] to remainingElementsCount.[[Value]] - 1.
              11. If remainingElementsCount.[[Value]] is 0, then
                1. Let valuesArray be CreateArrayFromList(values).
                2. Return ? Call(promiseCapability.[[Resolve]], undefined, « valuesArray »).
              12. Return undefined. @@ -37352,7 +37352,7 @@ resolves all elements of the passed iterable to promises as it runs this

                25.6.4.3Promise.race ( iterable )

                The race function returns a new promise which is - settled in the same way as the first passed promise to settle. It + settled in the same way as the first passed promise to settle. It resolves all elements of the passed iterable to promises as it runs this algorithm.

                1. Let C be the this value.
                2. If Type(C) is not Object, throw a TypeError exception.
                3. Let promiseCapability be ? NewPromiseCapability(C).
                4. Let iteratorRecord be GetIterator(iterable).
                5. IfAbruptRejectPromise(iteratorRecord, promiseCapability).
                6. Let result be PerformPromiseRace(iteratorRecord, C, promiseCapability).
                7. If result is an abrupt completion, then
                  1. If iteratorRecord.[[Done]] is false, set result to IteratorClose(iteratorRecord, result).
                  2. IfAbruptRejectPromise(result, promiseCapability).
                8. Return Completion(result).
                @@ -37384,7 +37384,7 @@ resolves all elements of the passed iterable to promises as it runs t

                25.6.4.5Promise.resolve ( x )

                -

                The resolve function returns either a new +

                The resolve function returns either a new promise resolved with the passed argument, or the argument itself if the argument is a promise produced by this constructor.

                1. Let C be the this value.
                2. If Type(C) is not Object, throw a TypeError exception.
                3. Return ? PromiseResolve(C, x). @@ -37444,7 +37444,7 @@ promise resolved with the passed argument, or the argument itself if the

                  25.6.5.3.1Then Finally Functions

                  -

                  A Then Finally function is an anonymous built-in function +

                  A Then Finally function is an anonymous built-in function that has a [[Constructor]] and an [[OnFinally]] internal slot. The value of the [[Constructor]] internal slot is a Promise-like constructor function object, and the value of the [[OnFinally]] internal slot is a function object.

                  When a Then Finally function is called with argument value, the following steps are taken:

                  @@ -37455,7 +37455,7 @@ that has a [[Constructor]] and an [[OnFinally]] internal slot. The value

                  25.6.5.3.2Catch Finally Functions

                  -

                  A Catch Finally function is an anonymous built-in function +

                  A Catch Finally function is an anonymous built-in function that has a [[Constructor]] and an [[OnFinally]] internal slot. The value of the [[Constructor]] internal slot is a Promise-like constructor function object, and the value of the [[OnFinally]] internal slot is a function object.

                  When a Catch Finally function is called with argument reason, the following steps are taken:

                  @@ -37475,7 +37475,7 @@ that has a [[Constructor]] and an [[OnFinally]] internal slot. The value

                  25.6.5.4.1PerformPromiseThen ( promise, onFulfilled, onRejected [ , resultCapability ] )

                  The abstract operation PerformPromiseThen performs the “then” operation on promise using onFulfilled and onRejected as its settlement actions. If resultCapability is passed, the result is stored by updating resultCapability's - promise. (If it is not passed, then PerformPromiseThen is being called + promise. (If it is not passed, then PerformPromiseThen is being called by a specification-internal operation where the result does not matter.)

                  1. Assert: IsPromise(promise) is true.
                  2. If resultCapability is present, then
                    1. Assert: resultCapability is a PromiseCapability Record.
                  3. Else,
                    1. Set resultCapability to undefined.
                  4. If IsCallable(onFulfilled) is false, then
                    1. Set onFulfilled to undefined.
                  5. If IsCallable(onRejected) is false, then
                    1. Set onRejected to undefined.
                  6. Let fulfillReaction be the PromiseReaction { [[Capability]]: resultCapability, [[Type]]: "Fulfill", [[Handler]]: onFulfilled }.
                  7. Let rejectReaction be the PromiseReaction { [[Capability]]: resultCapability, [[Type]]: "Reject", [[Handler]]: onRejected }.
                  8. If promise.[[PromiseState]] is "pending", then
                    1. Append fulfillReaction as the last element of the List that is promise.[[PromiseFulfillReactions]].
                    2. Append rejectReaction as the last element of the List that is promise.[[PromiseRejectReactions]].
                  9. Else if promise.[[PromiseState]] is "fulfilled", then
                    1. Let value be promise.[[PromiseResult]].
                    2. Perform EnqueueJob("PromiseJobs", PromiseReactionJob, « fulfillReaction, value »).
                  10. Else,
                    1. Assert: The value of promise.[[PromiseState]] is "rejected".
                    2. Let reason be promise.[[PromiseResult]].
                    3. If promise.[[PromiseIsHandled]] is false, perform HostPromiseRejectionTracker(promise, "handle").
                    4. Perform EnqueueJob("PromiseJobs", PromiseReactionJob, « rejectReaction, reason »).
                  11. Set promise.[[PromiseIsHandled]] to true.
                  12. If resultCapability is undefined, then
                    1. Return undefined.
                  13. Else,
                    1. Return resultCapability.[[Promise]].
                  @@ -37498,63 +37498,63 @@ by a specification-internal operation where the result does not matter.)

                  Internal Slot - + Description - + [[PromiseState]] - + A String value that governs how a promise will react to incoming calls to its then method. The possible values are: "pending", "fulfilled", and "rejected". - + [[PromiseResult]] - + - The value with which the promise has been fulfilled or + The value with which the promise has been fulfilled or rejected, if any. Only meaningful if [[PromiseState]] is not "pending". - + [[PromiseFulfillReactions]] - + A List of PromiseReaction records to be processed when/if the promise transitions from the "pending" state to the "fulfilled" state. - + [[PromiseRejectReactions]] - + A List of PromiseReaction records to be processed when/if the promise transitions from the "pending" state to the "rejected" state. - + [[PromiseIsHandled]] - + - A boolean indicating whether the promise has ever had a + A boolean indicating whether the promise has ever had a fulfillment or rejection handler; used in unhandled rejection tracking. - + @@ -37576,7 +37576,7 @@ fulfillment or rejection handler; used in unhandled rejection tracking.
                4. is a subclass of Function.
                5. creates and initializes a new AsyncFunction object when called as a function rather than as a constructor. Thus the function call AsyncFunction(…) is equivalent to the object creation expression new AsyncFunction(…) with the same arguments.
                6. is designed to be subclassable. It may be used as the value of an extends - clause of a class definition. Subclass constructors that intend to + clause of a class definition. Subclass constructors that intend to inherit the specified AsyncFunction behaviour must include a super call to the AsyncFunction constructor to create and initialize a subclass instance with the internal slots necessary for built-in async function behaviour.
                  7. @@ -37648,8 +37648,8 @@ inherit the specified AsyncFunction behaviour must include a super

                  25.7.4AsyncFunction Instances

                  Every AsyncFunction instance is an ECMAScript function object and has the internal slots listed in Table 27. The value of the [[FunctionKind]] internal slot for all such instances is "async". - AsyncFunction instances are not constructors and do not have a -[[Construct]] internal method. AsyncFunction instances do not have a + AsyncFunction instances are not constructors and do not have a +[[Construct]] internal method. AsyncFunction instances do not have a prototype property as they are not constructable.

                  Each AsyncFunction instance has the following own properties:

                  @@ -37669,7 +37669,7 @@ prototype property as they are not constructable.

                  25.7.5.1AsyncFunctionStart ( promiseCapability, asyncFunctionBody )

                  1. Let runningContext be the running execution context.
                  2. Let asyncContext be a copy of runningContext.
                  3. Set the code evaluation state of asyncContext such that when evaluation is resumed for that execution context the following steps will be performed:
                    1. Let result be the result of evaluating asyncFunctionBody.
                    2. Assert: - If we return here, the async function either threw an exception or + If we return here, the async function either threw an exception or performed an implicit or explicit return; all awaiting is done.
                    3. Remove asyncContext from the execution context stack and restore the execution context that is at the top of the execution context stack as the running execution context.
                    4. If result.[[Type]] is normal, then
                      1. Perform ! Call(promiseCapability.[[Resolve]], undefined, « undefined »).
                    5. Else if result.[[Type]] is return, then
                      1. Perform ! Call(promiseCapability.[[Resolve]], undefined, « result.[[Value]] »).
                    6. Else,
                      1. Assert: result.[[Type]] is throw.
                      2. Perform ! Call(promiseCapability.[[Reject]], undefined, « result.[[Value]] »).
                    7. Return.
                  4. Push asyncContext onto the execution context stack; asyncContext is now the running execution context.
                  5. Resume the suspended evaluation of asyncContext. Let result be the value returned by the resumed computation.
                  6. Assert: When we return here, asyncContext has already been removed from the execution context stack and runningContext is the currently running execution context.
                  7. Assert: result is a normal completion with a value of undefined. The possible sources of completion values are Await or, if the async function doesn't await anything, the step 3.g above.
                  8. Return.
                  @@ -37851,39 +37851,39 @@ performed an implicit or explicit return; all awaiting is done.
                7. Remove <

                  27Memory Model

                  The memory consistency model, or memory model, specifies the possible orderings of Shared Data Block - events, arising via accessing TypedArray instances backed by a -SharedArrayBuffer and via methods on the Atomics object. When the -program has no data races (defined below), the ordering of events -appears as sequentially consistent, i.e., as an interleaving of actions + events, arising via accessing TypedArray instances backed by a +SharedArrayBuffer and via methods on the Atomics object. When the +program has no data races (defined below), the ordering of events +appears as sequentially consistent, i.e., as an interleaving of actions from each agent. - When the program has data races, shared memory operations may appear -sequentially inconsistent. For example, programs may exhibit -causality-violating behaviour and other astonishments. These -astonishments arise from compiler transforms and the design of CPUs + When the program has data races, shared memory operations may appear +sequentially inconsistent. For example, programs may exhibit +causality-violating behaviour and other astonishments. These +astonishments arise from compiler transforms and the design of CPUs (e.g., out-of-order execution and speculation). The memory model defines both the precise conditions under which a program exhibits sequentially - consistent behaviour as well as the possible values read from data + consistent behaviour as well as the possible values read from data races. To wit, there is no undefined behaviour.

                  The memory model is defined as relational constraints on events introduced by abstract operations on SharedArrayBuffer or by methods on the Atomics object during an evaluation.

                  Note

                  This section provides an axiomatic model on events introduced by the abstract operations - on SharedArrayBuffers. It bears stressing that the model is not -expressible algorithmically, unlike the rest of this specification. The + on SharedArrayBuffers. It bears stressing that the model is not +expressible algorithmically, unlike the rest of this specification. The nondeterministic introduction of events by abstract operations - is the interface between the operational semantics of ECMAScript -evaluation and the axiomatic semantics of the memory model. The + is the interface between the operational semantics of ECMAScript +evaluation and the axiomatic semantics of the memory model. The semantics of these events is defined by considering graphs of all events - in an evaluation. These are neither Static Semantics nor Runtime -Semantics. There is no demonstrated algorithmic implementation, but -instead a set of constraints that determine if a particular event graph + in an evaluation. These are neither Static Semantics nor Runtime +Semantics. There is no demonstrated algorithmic implementation, but +instead a set of constraints that determine if a particular event graph is allowed or disallowed.

                  27.1Memory Model Fundamentals

                  -

                  Shared memory accesses (reads and writes) are divided into two -groups, atomic accesses and data accesses, defined below. Atomic -accesses are sequentially consistent, i.e., there is a strict total +

                  Shared memory accesses (reads and writes) are divided into two +groups, atomic accesses and data accesses, defined below. Atomic +accesses are sequentially consistent, i.e., there is a strict total ordering of events agreed upon by all agents in an agent cluster. Non-atomic accesses do not have a strict total ordering agreed upon by all agents, i.e., unordered.

                  Note 1

                  No orderings weaker than sequentially consistent and stronger than unordered, such as release-acquire, are supported.

                  @@ -38019,14 +38019,14 @@ ordering of events agreed upon by all agents in an abstract operations or by methods on the Atomics object.

                  Some operations may also introduce Synchronize events. A Synchronize event has no fields, and exists purely to directly constrain the permitted orderings of other events.

                  In addition to Shared Data Block and Synchronize events, there are host-specific events.

                  -

                  Let the range of a ReadSharedMemory, WriteSharedMemory, or +

                  Let the range of a ReadSharedMemory, WriteSharedMemory, or ReadModifyWriteSharedMemory event be the Set of contiguous integers from - its [[ByteIndex]] to [[ByteIndex]] + [[ElementSize]] - 1. Two events' + its [[ByteIndex]] to [[ByteIndex]] + [[ElementSize]] - 1. Two events' ranges are equal when the events have the same [[Block]], and the ranges - are element-wise equal. Two events' ranges are overlapping when the -events have the same [[Block]], the ranges are not equal and their -intersection is non-empty. Two events' ranges are disjoint when the -events do not have the same [[Block]] or their ranges are neither equal + are element-wise equal. Two events' ranges are overlapping when the +events have the same [[Block]], the ranges are not equal and their +intersection is non-empty. Two events' ranges are disjoint when the +events do not have the same [[Block]] or their ranges are neither equal nor overlapping.

                  Note 2

                  Examples of host-specific synchronizing events that should be accounted for are: sending a SharedArrayBuffer from one agent to another (e.g., by postMessage in a browser), starting and stopping agents, and communicating within the agent cluster via channels other than shared memory. It is assumed those events are appended to agent-order during evaluation like the other SharedArrayBuffer events.

                  @@ -38258,7 +38258,7 @@ nor overlapping.

                  • For each pair (R, W) in execution.[[ReadsFrom]], (W, R) is in execution.[[SynchronizesWith]] if all the following are true. - +
                    • R.[[Order]] is "SeqCst".
                    • W.[[Order]] is "SeqCst" or "Init".
                      • @@ -38268,7 +38268,7 @@ nor overlapping.

                    • For each element eventsRecord of execution.[[EventsRecords]], the following is true. - +
                      • For each pair (S, Sw) in eventsRecord.[[AgentSynchronizesWith]], (S, Sw) is in execution.[[SynchronizesWith]].
                      @@ -38330,13 +38330,13 @@ nor overlapping.

                      Note

                      An event's [[NoTear]] field is true when that event was introduced via accessing an integer TypedArray, and false when introduced via accessing a floating point TypedArray or DataView.

                      -

                      Intuitively, this requirement says when a memory range is +

                      Intuitively, this requirement says when a memory range is accessed in an aligned fashion via an integer TypedArray, a single write - event on that range must "win" when in a data race with other write -events with equal ranges. More precisely, this requirement says an -aligned read event cannot read a value composed of bytes from multiple, -different write events all with equal ranges. It is possible, however, -for an aligned read event to read from multiple write events with + event on that range must "win" when in a data race with other write +events with equal ranges. More precisely, this requirement says an +aligned read event cannot read a value composed of bytes from multiple, +different write events all with equal ranges. It is possible, however, +for an aligned read event to read from multiple write events with overlapping ranges.

                       @@ -38406,20 +38406,20 @@ overlapping ranges.

                      27.11Shared Memory Guidelines

                      Note 1

                      The following are guidelines for ECMAScript programmers working with shared memory.

                      -

                      We recommend programs be kept data race free, i.e., make it so -that it is impossible for there to be concurrent non-atomic operations -on the same memory location. Data race free programs have interleaving +

                      We recommend programs be kept data race free, i.e., make it so +that it is impossible for there to be concurrent non-atomic operations +on the same memory location. Data race free programs have interleaving semantics where each step in the evaluation semantics of each agent are interleaved with each other. For data race free programs, it is not necessary to understand the details of the memory model. The details are unlikely to build intuition that will help one to better write ECMAScript.

                      -

                      More generally, even if a program is not data race free it may -have predictable behaviour, so long as atomic operations are not -involved in any data races and the operations that race all have the -same access size. The simplest way to arrange for atomics not to be -involved in races is to ensure that different memory cells are used by -atomic and non-atomic operations and that atomic accesses of different -sizes are not used to access the same cells at the same time. +

                      More generally, even if a program is not data race free it may +have predictable behaviour, so long as atomic operations are not +involved in any data races and the operations that race all have the +same access size. The simplest way to arrange for atomics not to be +involved in races is to ensure that different memory cells are used by +atomic and non-atomic operations and that atomic accesses of different +sizes are not used to access the same cells at the same time. Effectively, the program should treat shared memory as strongly typed as much as possible. One still cannot depend on the ordering and timing of - non-atomic accesses that race, but if memory is treated as strongly + non-atomic accesses that race, but if memory is treated as strongly typed the racing accesses will not "tear" (bits of their values will not be mixed).

                       @@ -38428,15 +38428,15 @@ typed the racing accesses will not "tear" (bits of their values will not

                      The following are guidelines for ECMAScript implementers writing compiler transformations for programs using shared memory.

                      It is desirable to allow most program transformations that are valid in a single-agent setting in a multi-agent setting, to ensure that the performance of each agent in a multi-agent program is as good as it would be in a single-agent setting. Frequently these transformations are hard to judge. We outline - some rules about program transformations that are intended to be taken + some rules about program transformations that are intended to be taken as normative (in that they are implied by the memory model or stronger than what the memory model - implies) but which are likely not exhaustive. These rules are intended -to apply to program transformations that precede the introductions of + implies) but which are likely not exhaustive. These rules are intended +to apply to program transformations that precede the introductions of the events that make up the agent-order.

                      Let an agent-order slice be the subset of the agent-order pertaining to a single agent.

                      Let possible read values of a read event be the set of all values of ValueOfReadEvent for that event across all valid executions.

                      Any transformation of an agent-order slice that is valid in the - absence of shared memory is valid in the presence of shared memory, + absence of shared memory is valid in the presence of shared memory, with the following exceptions.

                      • @@ -38445,18 +38445,18 @@ with the following exceptions.

                      • Reads must be stable: Any given shared memory read must only observe a single value in an execution.

                        -

                        (For example, if what is semantically a single read in the -program is executed multiple times then the program is subsequently -allowed to observe only one of the values read. A transformation known +

                        (For example, if what is semantically a single read in the +program is executed multiple times then the program is subsequently +allowed to observe only one of the values read. A transformation known as rematerialization can violate this rule.)

                      • Writes must be stable: All observable writes to shared memory must follow from program semantics in an execution.

                        -

                        (For example, a transformation may not introduce certain -observable writes, such as by using read-modify-write operations on a +

                        (For example, a transformation may not introduce certain +observable writes, such as by using read-modify-write operations on a larger location to write a smaller datum, writing a value to memory that - the program could not have written, or writing a just-read value back -to the location it was read from, if that location could have been + the program could not have written, or writing a just-read value back +to the location it was read from, if that location could have been overwritten by another agent after the read.)

                      • @@ -38464,26 +38464,26 @@ overwritten by another a

                        (Counterintuitively, this rule in effect restricts transformations on writes, because writes have force in memory model insofar as to be read by read events. For example, writes may be moved and coalesced and sometimes reordered between two "SeqCst" operations, but the transformation may not remove every write that updates a location; some write must be preserved.)

                      -

                      Examples of transformations that remain valid are: merging -multiple non-atomic reads from the same location, reordering non-atomic -reads, introducing speculative non-atomic reads, merging multiple -non-atomic writes to the same location, reordering non-atomic writes to -different locations, and hoisting non-atomic reads out of loops even if -that affects termination. Note in general that aliased TypedArrays make +

                      Examples of transformations that remain valid are: merging +multiple non-atomic reads from the same location, reordering non-atomic +reads, introducing speculative non-atomic reads, merging multiple +non-atomic writes to the same location, reordering non-atomic writes to +different locations, and hoisting non-atomic reads out of loops even if +that affects termination. Note in general that aliased TypedArrays make it hard to prove that locations are different.

                   Note 3

                  The following are guidelines for ECMAScript implementers generating machine code for shared memory accesses.

                  -

                  For architectures with memory models no weaker than those of +

                  For architectures with memory models no weaker than those of ARM or Power, non-atomic stores and loads may be compiled to bare stores - and loads on the target architecture. Atomic stores and loads may be -compiled down to instructions that guarantee sequential consistency. If -no such instructions exist, memory barriers are to be employed, such as -placing barriers on both sides of a bare store or load. -Read-modify-write operations may be compiled to read-modify-write + and loads on the target architecture. Atomic stores and loads may be +compiled down to instructions that guarantee sequential consistency. If +no such instructions exist, memory barriers are to be employed, such as +placing barriers on both sides of a bare store or load. +Read-modify-write operations may be compiled to read-modify-write instructions on the target architectrue, such as LOCK-prefixed - instructions on x86, load-exclusive/store-exclusive instructions on + instructions on x86, load-exclusive/store-exclusive instructions on ARM, and load-link/store-conditional instructions on Power.

                  Specifically, the memory model is intended to allow code generation as follows.

                    @@ -38492,48 +38492,48 @@ ARM, and load-link/store-conditional instructions on Power.

                  • Functions are always assumed to perform atomic operations.
                  • Atomic operations are never implemented as read-modify-write operations on larger data, but as non-lock-free atomics if the platform - does not have atomic operations of the appropriate size. (We already -assume that every platform has normal memory access operations of every + does not have atomic operations of the appropriate size. (We already +assume that every platform has normal memory access operations of every interesting size.)

                  Naive code generation uses these patterns:

                  • Regular loads and stores compile to single load and store instructions.
                  • Lock-free atomic loads and stores compile to a full (sequentially consistent) fence, a regular load or store, and a full fence.
                    • -
                  • Lock-free atomic read-modify-write accesses compile to a +
                  • Lock-free atomic read-modify-write accesses compile to a full fence, an atomic read-modify-write instruction sequence, and a full fence.
                    • -
                  • Non-lock-free atomics compile to a spinlock acquire, a full +
                  • Non-lock-free atomics compile to a spinlock acquire, a full fence, a series of non-atomic load and store instructions, a full fence, and a spinlock release.
                  -

                  That mapping is correct so long as an atomic operation on an -address range does not race with a non-atomic write or with an atomic +

                  That mapping is correct so long as an atomic operation on an +address range does not race with a non-atomic write or with an atomic operation of different size. However, that is all we need: the memory model - effectively demotes the atomic operations involved in a race to + effectively demotes the atomic operations involved in a race to non-atomic status. On the other hand, the naive mapping is quite strong: - it allows atomic operations to be used as sequentially consistent + it allows atomic operations to be used as sequentially consistent fences, which the memory model does not actually guarantee.

                  A number of local improvements to those basic patterns are also intended to be legal:

                    -
                  • There are obvious platform-dependent improvements that -remove redundant fences. For example, on x86 the fences around -lock-free atomic loads and stores can always be omitted except for the -fence following a store, and no fence is needed for lock-free -read-modify-write instructions, as these all use LOCK-prefixed -instructions. On many platforms there are fences of several strengths, -and weaker fences can be used in certain contexts without destroying +
                  • There are obvious platform-dependent improvements that +remove redundant fences. For example, on x86 the fences around +lock-free atomic loads and stores can always be omitted except for the +fence following a store, and no fence is needed for lock-free +read-modify-write instructions, as these all use LOCK-prefixed +instructions. On many platforms there are fences of several strengths, +and weaker fences can be used in certain contexts without destroying sequential consistency.
                    • -
                  • Most modern platforms support lock-free atomics for all the -data sizes required by ECMAScript atomics. Should non-lock-free atomics -be needed, the fences surrounding the body of the atomic operation can -usually be folded into the lock and unlock steps. The simplest solution -for non-lock-free atomics is to have a single lock word per +
                  • Most modern platforms support lock-free atomics for all the +data sizes required by ECMAScript atomics. Should non-lock-free atomics +be needed, the fences surrounding the body of the atomic operation can +usually be folded into the lock and unlock steps. The simplest solution +for non-lock-free atomics is to have a single lock word per SharedArrayBuffer.
                    • -
                  • There are also more complicated platform-dependent local -improvements, requiring some code analysis. For example, two -back-to-back fences often have the same effect as a single fence, so if -code is generated for two atomic operations in sequence, only a single +
                  • There are also more complicated platform-dependent local +improvements, requiring some code analysis. For example, two +back-to-back fences often have the same effect as a single fence, so if +code is generated for two atomic operations in sequence, only a single fence need separate them. On x86, even a single fence separating atomic stores can be omitted, as the fence following a store is only needed to separate the store from a subsequent load.
                    • @@ -40003,25 +40003,25 @@ fence need separate them. On x86, even a single fence separating atomic

                    BAdditional ECMAScript Features for Web Browsers

                    -

                    The ECMAScript language syntax and semantics defined in this annex -are required when the ECMAScript host is a web browser. The content of +

                    The ECMAScript language syntax and semantics defined in this annex +are required when the ECMAScript host is a web browser. The content of this annex is normative but optional if the ECMAScript host is not a web browser.

                    Note
                    -

                    This annex describes various legacy features and other -characteristics of web browser based ECMAScript implementations. All of +

                    This annex describes various legacy features and other +characteristics of web browser based ECMAScript implementations. All of the language features and behaviours specified in this annex have one or - more undesirable characteristics and in the absence of legacy usage -would be removed from this specification. However, the usage of these -features by large numbers of existing web pages means that web browsers -must continue to support them. The specifications in this annex define -the requirements for interoperable implementations of these legacy + more undesirable characteristics and in the absence of legacy usage +would be removed from this specification. However, the usage of these +features by large numbers of existing web pages means that web browsers +must continue to support them. The specifications in this annex define +the requirements for interoperable implementations of these legacy features.

                    -

                    These features are not considered part of the core ECMAScript -language. Programmers should not use or assume the existence of these -features and behaviours when writing new ECMAScript code. ECMAScript -implementations are discouraged from implementing these features unless -the implementation is part of a web browser or is required to run the +

                    These features are not considered part of the core ECMAScript +language. Programmers should not use or assume the existence of these +features and behaviours when writing new ECMAScript code. ECMAScript +implementations are discouraged from implementing these features unless +the implementation is part of a web browser or is required to run the same legacy ECMAScript code that web browsers encounter.

                     @@ -40068,61 +40068,61 @@ same legacy ECMAScript code that web browsers encounter.

                    The MV of LegacyOctalIntegerLiteral::0OctalDigit is the MV of OctalDigit. - +
                  • The MV of LegacyOctalIntegerLiteral::LegacyOctalIntegerLiteralOctalDigit is (the MV of LegacyOctalIntegerLiteral times 8) plus the MV of OctalDigit. - +
                  • The MV of DecimalIntegerLiteral::NonOctalDecimalIntegerLiteral is the MV of NonOctalDecimalIntegerLiteral. - +
                  • The MV of NonOctalDecimalIntegerLiteral::0NonOctalDigit is the MV of NonOctalDigit. - +
                  • The MV of NonOctalDecimalIntegerLiteral::LegacyOctalLikeDecimalIntegerLiteralNonOctalDigit is (the MV of LegacyOctalLikeDecimalIntegerLiteral times 10) plus the MV of NonOctalDigit. - +
                  • The MV of NonOctalDecimalIntegerLiteral::NonOctalDecimalIntegerLiteralDecimalDigit is (the MV of NonOctalDecimalIntegerLiteral times 10) plus the MV of DecimalDigit. - +
                  • The MV of LegacyOctalLikeDecimalIntegerLiteral::0OctalDigit is the MV of OctalDigit. - +
                  • The MV of LegacyOctalLikeDecimalIntegerLiteral::LegacyOctalLikeDecimalIntegerLiteralOctalDigit is (the MV of LegacyOctalLikeDecimalIntegerLiteral times 10) plus the MV of OctalDigit. - +
                  • The MV of NonOctalDigit::8 is 8. - +
                  • The MV of NonOctalDigit::9 is 9. - +
                  @@ -40159,79 +40159,79 @@ same legacy ECMAScript code that web browsers encounter.

                  The SV of EscapeSequence::LegacyOctalEscapeSequence is the SV of the LegacyOctalEscapeSequence. - +
                8. The SV of LegacyOctalEscapeSequence::OctalDigit is the code unit whose value is the MV of the OctalDigit. - +
                9. The SV of LegacyOctalEscapeSequence::ZeroToThreeOctalDigit is the code unit whose value is (8 times the MV of the ZeroToThree) plus the MV of the OctalDigit. - +
                10. The SV of LegacyOctalEscapeSequence::FourToSevenOctalDigit is the code unit whose value is (8 times the MV of the FourToSeven) plus the MV of the OctalDigit. - +
                11. The SV of LegacyOctalEscapeSequence::ZeroToThreeOctalDigitOctalDigit is the code unit whose value is (64 (that is, 82) times the MV of the ZeroToThree) plus (8 times the MV of the first OctalDigit) plus the MV of the second OctalDigit. - +
                12. The MV of ZeroToThree::0 is 0. - +
                13. The MV of ZeroToThree::1 is 1. - +
                14. The MV of ZeroToThree::2 is 2. - +
                15. The MV of ZeroToThree::3 is 3. - +
                16. The MV of FourToSeven::4 is 4. - +
                17. The MV of FourToSeven::5 is 5. - +
                18. The MV of FourToSeven::6 is 6. - +
                19. The MV of FourToSeven::7 is 7. - +
                  20. @@ -40292,15 +40292,15 @@ same legacy ECMAScript code that web browsers encounter.

                  B.1.4Regular Expressions Patterns

                  The syntax of 21.2.1 - is modified and extended as follows. These changes introduce -ambiguities that are broken by the ordering of grammar productions and -by contextual information. When parsing using the following grammar, -each alternative is considered only if previous production alternatives + is modified and extended as follows. These changes introduce +ambiguities that are broken by the ordering of grammar productions and +by contextual information. When parsing using the following grammar, +each alternative is considered only if previous production alternatives do not match.

                  This alternative pattern grammar and semantics only changes the - syntax and semantics of BMP patterns. The following grammar extensions -include productions parameterized with the [U] parameter. However, none -of these extensions change the syntax of Unicode patterns recognized + syntax and semantics of BMP patterns. The following grammar extensions +include productions parameterized with the [U] parameter. However, none +of these extensions change the syntax of Unicode patterns recognized when parsing with the [U] parameter present on the goal symbol.

                  Syntax

                  @@ -40399,7 +40399,7 @@ when parsing with the [U] parameter present on the @@ -40408,7 +40408,7 @@ when parsing with the [U] parameter present on the ClassAtom is true or IsCharacterClass of the second ClassAtom is true and this production has a [U] parameter. - + @@ -40417,7 +40417,7 @@ when parsing with the [U] parameter present on the ClassAtomNoDash is true or IsCharacterClass of ClassAtom is true and this production has a [U] parameter. - +                   @@ -40567,43 +40567,43 @@ when parsing with the [U] parameter present on the %escape% - + escape - + The escape function (B.2.1.1) - + %unescape% - + unescape - + The unescape function (B.2.1.2) - + @@ -40618,9 +40618,9 @@ when parsing with the [U] parameter present on the ToString(string).
                20. Let length be the number of code units in string.
                21. Let R be the empty string.
                22. Let k be 0.
                23. Repeat, while k < length,
                  1. Let char be the code unit (represented as a 16-bit unsigned integer) at index k within string.
                  2. If char is one of the code units in "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789@*_+-./", then
                    1. Let S be the String value containing the single code unit char.
                  3. Else if char ≥ 256, then
                    1. Let n be the numeric value of char.
                    2. Let S be the string-concatenation of:
                      • "%u"
                      • the String representation of n, formatted as a four-digit uppercase hexadecimal number, padded to the left with zeroes if necessary
                  4. Else char < 256,
                    1. Let n be the numeric value of char.
                    2. Let S be the string-concatenation of:
                      • "%"
                      • the String representation of n, formatted as a two-digit uppercase hexadecimal number, padded to the left with a zero if necessary
                  5. Set R to the string-concatenation of the previous value of R and S.
                  6. Increase k by 1.
                24. Return R.
                Note
                -

                The encoding is partly based on the encoding described in -RFC 1738, but the entire encoding specified in this standard is -described above without regard to the contents of RFC 1738. This +

                The encoding is partly based on the encoding described in +RFC 1738, but the entire encoding specified in this standard is +described above without regard to the contents of RFC 1738. This encoding does not reflect changes to RFC 1738 made by RFC 3986.

                 @@ -40855,9 +40855,9 @@ encoding does not reflect changes to RFC 1738 made by RFC 3986.

               Note

              The compile method completely reinitializes the this - object RegExp with a new pattern and flags. An implementation may -interpret use of this method as an assertion that the resulting RegExp -object will be used multiple times and hence is a candidate for extra + object RegExp with a new pattern and flags. An implementation may +interpret use of this method as an assertion that the resulting RegExp +object will be used multiple times and hence is a candidate for extra optimization.

               @@ -40881,14 +40881,14 @@ optimization.

              It is a Syntax Error if PropertyNameList of PropertyDefinitionList contains any duplicate entries for "__proto__" and at least two of those entries were obtained from productions of the form PropertyDefinition:PropertyName:AssignmentExpression . - +
              9. Note

              The List returned by PropertyNameList does not include string literal property names defined as using a ComputedPropertyName.

              In 12.2.6.8 the PropertyDefinitionEvaluation algorithm for the production - +
              PropertyDefinition:PropertyName:AssignmentExpression @@ -40905,8 +40905,8 @@ optimization.

              B.3.2Labelled Function Declarations

              Prior to ECMAScript 2015, the specification of LabelledStatement did not allow for the association of a statement label with a FunctionDeclaration. However, a labelled FunctionDeclaration was an allowable extension for non-strict code and most browser-hosted ECMAScript implementations supported that extension. In ECMAScript 2015, the grammar productions for LabelledStatement permits use of FunctionDeclaration as a LabelledItem but 13.13.1 - includes an Early Error rule that produces a Syntax Error if that -occurs. For web browser compatibility, that rule is modified with the + includes an Early Error rule that produces a Syntax Error if that +occurs. For web browser compatibility, that rule is modified with the addition of the highlighted text:

              LabelledItem:FunctionDeclaration @@ -40914,7 +40914,7 @@ addition of the highlighted text:

              • It is a Syntax Error if any strict mode source code matches this rule. - +
              Note
              @@ -40925,14 +40925,14 @@ addition of the highlighted text:

              B.3.3Block-Level Function Declarations Web Legacy Compatibility Semantics

              Prior to ECMAScript 2015, the ECMAScript specification did not define the occurrence of a FunctionDeclaration as an element of a Block statement's StatementList. However, support for that form of FunctionDeclaration - was an allowable extension and most browser-hosted ECMAScript -implementations permitted them. Unfortunately, the semantics of such -declarations differ among those implementations. Because of these + was an allowable extension and most browser-hosted ECMAScript +implementations permitted them. Unfortunately, the semantics of such +declarations differ among those implementations. Because of these semantic differences, existing web ECMAScript code that uses Block - level function declarations is only portable among browser -implementation if the usage only depends upon the semantic intersection -of all of the browser implementations for such declarations. The -following are the use cases that fall within that intersection + level function declarations is only portable among browser +implementation if the usage only depends upon the semantic intersection +of all of the browser implementations for such declarations. The +following are the use cases that fall within that intersection semantics:

              1. @@ -40940,15 +40940,15 @@ semantics:

                • One or more FunctionDeclarations whose BindingIdentifier is the name f occur within the function code of an enclosing function g and that declaration is nested within a Block. - +
                • No other declaration of f that is not a var declaration occurs within the function code of g - +
                • All occurrences of f as an IdentifierReference are within the StatementList of the Block containing the declaration of f. - +
                2. @@ -40957,23 +40957,23 @@ semantics:

                • One or more FunctionDeclarations whose BindingIdentifier is the name f occur within the function code of an enclosing function g and that declaration is nested within a Block. - +
                • No other declaration of f that is not a var declaration occurs within the function code of g - +
                • There may be occurrences of f as an IdentifierReference within the StatementList of the Block containing the declaration of f. - +
                • There is at least one occurrence of f as an IdentifierReference within another function h that is nested within g and no other declaration of f shadows the references to f from within h. - +
                • All invocations of h occur after the declaration of f has been evaluated. - +
                @@ -40982,35 +40982,35 @@ semantics:

                • One or more FunctionDeclaration whose BindingIdentifier is the name f occur within the function code of an enclosing function g and that declaration is nested within a Block. - +
                • No other declaration of f that is not a var declaration occurs within the function code of g - +
                • There may be occurrences of f as an IdentifierReference within the StatementList of the Block containing the declaration of f. - +
                • There is at least one occurrence of f as an IdentifierReference within the function code of g that lexically follows the Block containing the declaration of f. - +

              The first use case is interoperable with the semantics of Block - level function declarations provided by ECMAScript 2015. Any -pre-existing ECMAScript code that employs that use case will operate + level function declarations provided by ECMAScript 2015. Any +pre-existing ECMAScript code that employs that use case will operate using the Block level function declarations semantics defined by clauses 9, 13, and 14 of this specification.

              ECMAScript 2015 interoperability for the second and third use cases requires the following extensions to the clause 9, clause 14, clause 18.2.1 and clause 15.1.11 semantics.

              -

              If an ECMAScript implementation has a mechanism for reporting -diagnostic warning messages, a warning should be produced when code +

              If an ECMAScript implementation has a mechanism for reporting +diagnostic warning messages, a warning should be produced when code contains a FunctionDeclaration - for which these compatibility semantics are applied and introduce + for which these compatibility semantics are applied and introduce observable differences from non-compatibility semantics. For example, if - a var binding is not introduced because its introduction would create + a var binding is not introduced because its introduction would create an early error, a warning message should not be produced.

              B.3.3.1Changes to FunctionDeclarationInstantiation

              @@ -41086,23 +41086,23 @@ an early err Note

              The Block of a Catch clause may contain var declarations that bind a name that is also bound by the CatchParameter. - At runtime, such bindings are instantiated in the -VariableDeclarationEnvironment. They do not shadow the same-named + At runtime, such bindings are instantiated in the +VariableDeclarationEnvironment. They do not shadow the same-named bindings introduced by the CatchParameter and hence the Initializer for such var declarations will assign to the corresponding catch parameter rather than the var binding.

              This modified behaviour also applies to var and function declarations introduced by direct eval calls contained within the Block of a Catch clause. This change is accomplished by modifying the algorithm of 18.2.1.3 as follows:

              @@ -41173,7 +41173,7 @@ bindings introduced by the Note

              Objects with an [[IsHTMLDDA]] internal slot are never created by this specification. However, the document.all object in web browsers is a host-created exotic object with this slot that exists for web compatibility purposes. There are no - other known examples of this type of object and implementations should + other known examples of this type of object and implementations should not create any with the exception of document.all.

              @@ -41194,31 +41194,31 @@ not create any with the exception of document.all.

              B.3.7.3Changes to the typeof Operator

              The following table entry is inserted into Table 35 immediately preceeding the entry for "Object (implements [[Call]])":

              -
              Table 84: +
              Table 84: Additional typeof Operator Results - +
              - + @@ -41235,75 +41235,75 @@ not create any with the exception of document.all.

              • implements, interface, let, package, private, protected, public, static, and yield are reserved words within strict mode code. (11.6.2). - +
              • A conforming implementation, when processing strict mode code, must not extend, as described in B.1.1, the syntax of NumericLiteral to include LegacyOctalIntegerLiteral, nor extend the syntax of DecimalIntegerLiteral to include NonOctalDecimalIntegerLiteral. - +
              • A conforming implementation, when processing strict mode code, may not extend the syntax of EscapeSequence to include LegacyOctalEscapeSequence as described in B.1.2. - +
              • Assignment to an undeclared identifier or otherwise unresolvable reference does not create a property in the global object. When a simple assignment occurs within strict mode code, its LeftHandSideExpression must not evaluate to an unresolvable Reference. If it does a ReferenceError exception is thrown (6.2.4.9). The LeftHandSideExpression also may not be a reference to a data property with the attribute value { [[Writable]]: false }, to an accessor property with the attribute value { [[Set]]: undefined }, nor to a non-existent property of an object whose [[Extensible]] internal slot has the value false. In these cases a TypeError exception is thrown (12.15). - +
              • An IdentifierReference with the StringValue "eval" or "arguments" may not appear as the LeftHandSideExpression of an Assignment operator (12.15) or of an UpdateExpression (12.4) or as the UnaryExpression operated upon by a Prefix Increment (12.4.6) or a Prefix Decrement (12.4.7) operator. - +
              • Arguments objects for strict functions define a non-configurable accessor property "callee" which throws a TypeError exception on access (9.4.4.6). - +
              • Arguments objects for strict functions do not dynamically share their array-indexed property values with the corresponding formal parameter bindings of their functions. (9.4.4). - +
              • For strict functions, if an arguments object is created the binding of the local identifier arguments to the arguments object is immutable and hence may not be the target of an assignment expression. (9.2.15). - +
              • It is a SyntaxError if the StringValue of a BindingIdentifier is "eval" or "arguments" within strict mode code (12.1.1). - +
              • Strict mode eval code cannot instantiate variables or functions in the variable environment of the caller to eval. Instead, a new variable - environment is created and that environment is used for declaration + environment is created and that environment is used for declaration binding instantiation for the eval code (18.2.1). - +
              • If this is evaluated within strict mode code, then the this value is not coerced to an object. A this value of undefined or null is not converted to the global object and primitive values are not converted to wrapper objects. The this value passed via a function call (including calls made using Function.prototype.apply and Function.prototype.call) do not coerce the passed this value to an object (9.2.1.2, 19.2.3.1, 19.2.3.3). - +
              • When a delete operator occurs within strict mode code, a SyntaxError is thrown if its UnaryExpression is a direct reference to a variable, function argument, or function name (12.5.3.1). - +
              • When a delete operator occurs within strict mode code, a TypeError is thrown if the property to be deleted has the attribute { [[Configurable]]: false } (12.5.3.2). - +
              • Strict mode code may not include a WithStatement. The occurrence of a WithStatement in such a context is a SyntaxError (13.11.1). - +
              • It is a SyntaxError if a CatchParameter occurs within strict mode code and BoundNames of CatchParameter contains either eval or arguments (13.15.1). - +
              • It is a SyntaxError if the same BindingIdentifier appears more than once in the FormalParameters of a strict function. An attempt to create such a function using a Function, Generator, or AsyncFunction constructor is a SyntaxError (14.1.2, 19.2.1.1.1). - +
              • - An implementation may not extend, beyond that defined in this + An implementation may not extend, beyond that defined in this specification, the meanings within strict functions of properties named caller or arguments of function instances. - +
              @@ -41311,18 +41311,18 @@ specification, the meanings within strict functions of properties named ca

              DCorrections and Clarifications in ECMAScript 2015 with Possible Compatibility Impact

              8.1.1.4.15-8.1.1.4.18 Edition 5 and 5.1 used a property existence test to determine whether a global object - property corresponding to a new global declaration already existed. + property corresponding to a new global declaration already existed. ECMAScript 2015 uses an own property existence test. This corresponds to what has been most commonly implemented by web browsers.

              9.4.2.1: The 5th Edition moved the capture of the current array length prior to the integer conversion of the array index - or new length value. However, the captured length value could become -invalid if the conversion process has the side-effect of changing the -array length. ECMAScript 2015 specifies that the current array length + or new length value. However, the captured length value could become +invalid if the conversion process has the side-effect of changing the +array length. ECMAScript 2015 specifies that the current array length must be captured after the possible occurrence of such side-effects.

              20.3.1.14: Previous editions permitted the TimeClip abstract operation to return either +0 or -0 as the representation of a 0 time value. ECMAScript 2015 specifies that +0 always returned. This means that for ECMAScript 2015 the time value of a Date object is never observably -0 and methods that return time values never return -0.

              20.3.1.15: - If a time zone offset is not present, the local time zone is used. -Edition 5.1 incorrectly stated that a missing time zone should be + If a time zone offset is not present, the local time zone is used. +Edition 5.1 incorrectly stated that a missing time zone should be interpreted as "z".

              20.3.4.36: If the year cannot be represented using the Date Time String Format specified in 20.3.1.15 a RangeError exception is thrown. Previous editions did not specify the behaviour for that case.

              20.3.4.41: Previous editions did not specify the value returned by Date.prototype.toString when this time value is NaN. ECMAScript 2015 specifies the result to be the String value is "Invalid Date".

              @@ -41337,9 +41337,9 @@ interpreted as "z".

              6.2.4: In ECMAScript 2015, Function calls are not allowed to return a Reference value.

              11.6: In ECMAScript 2015, the valid code points for an IdentifierName are specified in terms of the Unicode properties “ID_Start” and “ID_Continue”. In previous editions, the valid IdentifierName or Identifier code points were specified by enumerating various Unicode code point categories.

              11.9.1: - In ECMAScript 2015, Automatic Semicolon Insertion adds a semicolon at + In ECMAScript 2015, Automatic Semicolon Insertion adds a semicolon at the end of a do-while statement if the semicolon is missing. This change - aligns the specification with the actual behaviour of most existing + aligns the specification with the actual behaviour of most existing implementations.

              12.2.6.1: In ECMAScript 2015, it is no longer an early error to have duplicate property names in Object Initializers.

              12.15.1: In ECMAScript 2015, strict mode code containing an assignment to an immutable binding such as the function name of a FunctionExpression does not produce an early error. Instead it produces a runtime error.

              @@ -41349,15 +41349,15 @@ implementations.

              13.7: In ECMAScript 2015, if the ( token of a for statement is immediately followed by the token sequence let [ then the let is treated as the start of a LexicalDeclaration. In previous editions such a token sequence would be the start of an Expression.

              13.7: In ECMAScript 2015, if the ( token of a for-in statement is immediately followed by the token sequence let [ then the let is treated as the start of a ForDeclaration. In previous editions such a token sequence would be the start of an LeftHandSideExpression.

              13.7: Prior to ECMAScript 2015, an initialization expression could appear as part of the VariableDeclaration that precedes the in keyword. In ECMAScript 2015, the ForBinding - in that same position does not allow the occurrence of such an -initializer. In ECMAScript 2017, such an initializer is permitted only + in that same position does not allow the occurrence of such an +initializer. In ECMAScript 2017, such an initializer is permitted only in non-strict code.

              13.7: In ECMAScript 2015, the completion value of an IterationStatement is never the value empty. If the Statement part of an IterationStatement is not evaluated or if the final evaluation of the Statement part produces a completion whose value is empty, the completion value of the IterationStatement is undefined.

              13.11.7: In ECMAScript 2015, the normal completion value of a WithStatement is never the value empty. If evaluation of the Statement part of a WithStatement produces a normal completion whose value is empty, the completion value of the WithStatement is undefined.

              13.12.11: In ECMAScript 2015, the completion value of a SwitchStatement is never the value empty. If the CaseBlock part of a SwitchStatement produces a completion whose value is empty, the completion value of the SwitchStatement is undefined.

              13.15: In ECMAScript 2015, it is an early error for a Catch clause to contain a var declaration for the same Identifier that appears as the Catch - clause parameter. In previous editions, such a variable declaration -would be instantiated in the enclosing variable environment but the + clause parameter. In previous editions, such a variable declaration +would be instantiated in the enclosing variable environment but the declaration's Initializer value would be assigned to the Catch parameter.

              13.15, 18.2.1.3: In ECMAScript 2015, a runtime SyntaxError is thrown if a Catch clause evaluates a non-strict direct eval whose eval code includes a var or FunctionDeclaration declaration that binds the same Identifier that appears as the Catch clause parameter.

              13.15.8: In ECMAScript 2015, the completion value of a TryStatement is never the value empty. If the Block part of a TryStatement evaluates to a normal completion whose value is empty, the completion value of the TryStatement is undefined. If the Block part of a TryStatement evaluates to a throw completion and it has a Catch part that evaluates to a normal completion whose value is empty, the completion value of the TryStatement is undefined if there is no Finally clause or if its Finally clause evalulates to an empty normal completion.

              @@ -41365,86 +41365,86 @@ declaration's InitializerObjectLiteral are not constructor functions and they do not have a prototype own property. In the previous edition, they were constructors and had a prototype property.

              19.1.2.6: In ECMAScript 2015, if the argument to Object.freeze - is not an object it is treated as if it was a non-extensible ordinary -object with no own properties. In the previous edition, a non-object + is not an object it is treated as if it was a non-extensible ordinary +object with no own properties. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.1.2.8: In ECMAScript 2015, if the argument to Object.getOwnPropertyDescriptor is not an object an attempt is made to coerce the argument using ToObject. - If the coercion is successful the result is used in place of the -original argument value. In the previous edition, a non-object argument + If the coercion is successful the result is used in place of the +original argument value. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.1.2.10: In ECMAScript 2015, if the argument to Object.getOwnPropertyNames is not an object an attempt is made to coerce the argument using ToObject. - If the coercion is successful the result is used in place of the -original argument value. In the previous edition, a non-object argument + If the coercion is successful the result is used in place of the +original argument value. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.1.2.12: In ECMAScript 2015, if the argument to Object.getPrototypeOf is not an object an attempt is made to coerce the argument using ToObject. - If the coercion is successful the result is used in place of the -original argument value. In the previous edition, a non-object argument + If the coercion is successful the result is used in place of the +original argument value. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.1.2.14: In ECMAScript 2015, if the argument to Object.isExtensible - is not an object it is treated as if it was a non-extensible ordinary -object with no own properties. In the previous edition, a non-object + is not an object it is treated as if it was a non-extensible ordinary +object with no own properties. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.1.2.15: In ECMAScript 2015, if the argument to Object.isFrozen - is not an object it is treated as if it was a non-extensible ordinary -object with no own properties. In the previous edition, a non-object + is not an object it is treated as if it was a non-extensible ordinary +object with no own properties. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.1.2.16: In ECMAScript 2015, if the argument to Object.isSealed - is not an object it is treated as if it was a non-extensible ordinary -object with no own properties. In the previous edition, a non-object + is not an object it is treated as if it was a non-extensible ordinary +object with no own properties. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.1.2.17: In ECMAScript 2015, if the argument to Object.keys is not an object an attempt is made to coerce the argument using ToObject. - If the coercion is successful the result is used in place of the -original argument value. In the previous edition, a non-object argument + If the coercion is successful the result is used in place of the +original argument value. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.1.2.18: In ECMAScript 2015, if the argument to Object.preventExtensions - is not an object it is treated as if it was a non-extensible ordinary -object with no own properties. In the previous edition, a non-object + is not an object it is treated as if it was a non-extensible ordinary +object with no own properties. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.1.2.20: In ECMAScript 2015, if the argument to Object.seal - is not an object it is treated as if it was a non-extensible ordinary -object with no own properties. In the previous edition, a non-object + is not an object it is treated as if it was a non-extensible ordinary +object with no own properties. In the previous edition, a non-object argument always causes a TypeError to be thrown.

              19.2.3.2: In ECMAScript 2015, the [[Prototype]] internal slot of a bound function is set to the [[GetPrototypeOf]] value of its target function. In the previous edition, [[Prototype]] was always set to %FunctionPrototype%.

              19.2.4.1: In ECMAScript 2015, the "length" property of function instances is configurable. In previous editions it was non-configurable.

              19.5.6.2: In ECMAScript 2015, the [[Prototype]] internal slot of a NativeError constructor is the Error constructor. In previous editions it was the Function prototype object.

              20.3.4 - In ECMAScript 2015, the Date prototype object is not a Date instance. + In ECMAScript 2015, the Date prototype object is not a Date instance. In previous editions it was a Date instance whose TimeValue was NaN.

              21.1.3.10 In ECMAScript 2015, the String.prototype.localeCompare - function must treat Strings that are canonically equivalent according -to the Unicode standard as being identical. In previous editions + function must treat Strings that are canonically equivalent according +to the Unicode standard as being identical. In previous editions implementations were permitted to ignore canonical equivalence and could instead use a bit-wise comparison.

              21.1.3.24 and 21.1.3.26 - In ECMAScript 2015, lowercase/upper conversion processing operates on -code points. In previous editions such the conversion processing was + In ECMAScript 2015, lowercase/upper conversion processing operates on +code points. In previous editions such the conversion processing was only applied to individual code units. The only affected code points are those in the Deseret block of Unicode.

              21.1.3.27 In ECMAScript 2015, the String.prototype.trim - method is defined to recognize white space code points that may exists + method is defined to recognize white space code points that may exists outside of the Unicode BMP. However, as of Unicode 7 no such code points - are defined. In previous editions such code points would not have been + are defined. In previous editions such code points would not have been recognized as white space.

              21.2.3.1 In ECMAScript 2015, If the pattern argument is a RegExp instance and the flags argument is not undefined, a new RegExp instance is created just like pattern except that pattern's flags are replaced by the argument flags. In previous editions a TypeError exception was thrown when pattern was a RegExp instance and flags was not undefined.

              21.2.5 - In ECMAScript 2015, the RegExp prototype object is not a RegExp + In ECMAScript 2015, the RegExp prototype object is not a RegExp instance. In previous editions it was a RegExp instance whose pattern is the empty string.

              21.2.5 In ECMAScript 2015, source, global, ignoreCase, and multiline - are accessor properties defined on the RegExp prototype object. In + are accessor properties defined on the RegExp prototype object. In previous editions they were data properties defined on RegExp instances.

              FColophon

              This specification is authored on GitHub in a plaintext source format called Ecmarkup. - Ecmarkup is an HTML and Markdown dialect that provides a framework and -toolset for authoring ECMAScript specifications in plaintext and -processing the specification into a full-featured HTML rendering that -follows the editorial conventions for this document. Ecmarkup builds on + Ecmarkup is an HTML and Markdown dialect that provides a framework and +toolset for authoring ECMAScript specifications in plaintext and +processing the specification into a full-featured HTML rendering that +follows the editorial conventions for this document. Ecmarkup builds on and integrates a number of other formats and technologies including Grammarkdown for defining syntax and Ecmarkdown for authoring algorithm steps. PDF renderings of this specification are produced by printing the HTML rendering to a PDF.

              -

              Prior editions of this specification were authored using Word—the -Ecmarkup source text that formed the basis of this edition was produced -by converting the ECMAScript 2015 Word document to Ecmarkup using an +

              Prior editions of this specification were authored using Word—the +Ecmarkup source text that formed the basis of this edition was produced +by converting the ECMAScript 2015 Word document to Ecmarkup using an automated conversion tool.

               @@ -41452,62 +41452,62 @@ automated conversion tool.

              1. IEEE Std 754-2008: IEEE Standard for Floating-Point Arithmetic. Institute of Electrical and Electronic Engineers, New York (2008) - +
              2. The Unicode Standard, available at <https://unicode.org/versions/latest> - +
              3. Unicode Technical Note #5: Canonical Equivalence in Applications, available at <https://unicode.org/notes/tn5/> - +
              4. Unicode Technical Standard #10: Unicode Collation Algorithm, available at <https://unicode.org/reports/tr10/> - +
              5. Unicode Standard Annex #15, Unicode Normalization Forms, available at <https://unicode.org/reports/tr15/> - +
              6. Unicode Standard Annex #18: Unicode Regular Expressions, available at <https://unicode.org/reports/tr18/> - +
              7. Unicode Standard Annex #24: Unicode Script Property, available at <https://unicode.org/reports/tr24/> - +
              8. Unicode Standard Annex #31, Unicode Identifiers and Pattern Syntax, available at <https://unicode.org/reports/tr31/> - +
              9. Unicode Standard Annex #44: Unicode Character Database, available at <https://unicode.org/reports/tr44/> - +
              10. Unicode Technical Standard #51: Unicode Emoji, available at <https://unicode.org/reports/tr51/> - +
              11. IANA Time Zone Database, available at <https://www.iana.org/time-zones> - +
              12. ISO 8601:2004(E) Data elements and interchange formats – Information interchange — Representation of dates and times
              13. RFC 1738 “Uniform Resource Locators (URL)”, available at <https://tools.ietf.org/html/rfc1738> - +
              14. RFC 2396 “Uniform Resource Identifiers (URI): Generic Syntax”, available at <https://tools.ietf.org/html/rfc2396> - +
              15. RFC 3629 “UTF-8, a transformation format of ISO 10646”, available at <https://tools.ietf.org/html/rfc3629> - +
              @@ -41523,81 +41523,81 @@ automated conversion tool.

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               -
              References to
              Type of val - + Result - +
              Object (has an [[IsHTMLDDA]] internal slot) - + "undefined" - +
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