minify-html

A Rust HTML minifier meticulously optimised for speed and effectiveness, with bindings for other languages. - Advanced minification strategy beats other minifiers while being much faster. - Uses SIMD searching, direct tries, and lookup tables. - Handles [invalid HTML](./notes/Parsing.md), with extensive testing and [fuzzing](./fuzz). - Natively binds to [esbuild](https://github.com/wilsonzlin/esbuild-rs) for super fast JS and CSS minification. ## Performance Comparison with [html-minfier](https://github.com/kangax/html-minifier) and [minimize](https://github.com/Swaagie/minimize), run on the top web pages. [See the breakdown here.](./bench) Chart showing speed of HTML minifiers

Chart showing compression of HTML minifiers

The [onepass](https://github.com/wilsonzlin/minify-html/tree/master/rust/onepass) variant is even more optimised for speed. See its [README](https://github.com/wilsonzlin/minify-html/tree/master/rust/onepass) for more details. ## Usage

CLI

Precompiled binaries are available for Linux, macOS, and Windows. ### Get [Linux x86-64](https://wilsonl.in/minify-html/bin/0.6.1-linux-x86_64) | [Linux ARM](https://wilsonl.in/minify-html/bin/0.6.1-linux-arm64) | [macOS](https://wilsonl.in/minify-html/bin/0.6.1-macos-x86_64) | [Windows](https://wilsonl.in/minify-html/bin/0.6.1-windows-x86_64.exe) ### Use Use the `--help` argument for more details. ```bash minify-html --output /path/to/output.min.html --keep-closing-tags --minify-css /path/to/src.html ```

Rust

### Get ```toml [dependencies] minify-html = { version = "0.6.1", features = ["js-esbuild"] } ``` Building with the `js-esbuild` feature requires the Go compiler to be installed as well, to build the [JS and CSS minifier](https://github.com/wilsonzlin/esbuild-rs). If the `js-esbuild` feature is not enabled, `cfg.minify_js` and `cfg.minify_css` will have no effect. ### Use Check out the [docs](https://docs.rs/minify-html) for API and usage examples.

Node.js

- Package: [@minify-html/js](https://www.npmjs.com/package/@minify-html/js) - Binding: [N-API](https://nodejs.org/api/n-api.html) - Platforms: Linux (ARM64 and x86-64), macOS (x86-64), Windows (x86-64); Node.js 8.6.0 and higher ### Get Using npm: ```bash npm i @minify-html/js ``` Using Yarn: ```bash yarn add @minify-html/js ``` ### Use ```js const minifyHtml = require("@minify-html/js"); // Refer to TypeScript definitions for details. const cfg = minifyHtml.createConfiguration({ keep_closing_tags: true, remove_bangs: false }); const minified = minifyHtml.minify("

Hello, world!

", cfg); ``` minify-html is also available for TypeScript: ```ts import * as minifyHtml from "@minify-html/js"; import * as fs from "fs"; const cfg = minifyHtml.createConfiguration({ keep_spaces_between_attributes: true, keep_comments: true }); const minified = minifyHtml.minify("

Hello, world!

", cfg); ```

Java

- Package: [in.wilsonl.minifyhtml](https://search.maven.org/artifact/in.wilsonl.minifyhtml/minify-html) - Binding: [JNI](https://github.com/jni-rs/jni-rs) - Platforms: Linux, macOS, Windows; Java 7 and higher ### Get Add as a Maven dependency: ```xml in.wilsonl.minifyhtml minify-html 0.6.1 ``` ### Use ```java import in.wilsonl.minifyhtml.Configuration; import in.wilsonl.minifyhtml.MinifyHtml; import in.wilsonl.minifyhtml.SyntaxException; Configuration cfg = new Configuration.Builder() .setKeepHtmlAndHeadOpeningTags(true) .setMinifyCss(true) .build(); String minified = MinifyHtml.minify("

Hello, world!

", cfg); ```

Python

- Package: [minify-html](https://pypi.org/project/minify-html) - Binding: [PyO3](https://github.com/PyO3/pyo3) - Platforms: Linux, macOS, Windows; Python 3.7 and higher ### Get Add the PyPI project as a dependency and install it using `pip` or `pipenv`. ### Use ```python import minify_html minified = minify_html.minify("

Hello, world!

", minify_js=True, remove_processing_instructions=True) ```

Ruby

- Package: [minify_html](https://rubygems.org/gems/minify_html) - Binding: [Rutie](https://github.com/danielpclark/rutie) - Platforms: Linux, macOS; Ruby 2.5 and higher ### Get Add the library as a dependency to `Gemfile` or `*.gemspec`. ### Use ```ruby require 'minify_html' print MinifyHtml.minify("

Hello, world!

", { :keep_spaces_between_attributes => true, :minify_js => true }) ```

## Minification Note that some of the minification done can result in HTML that will not pass validation, but remain interpreted and rendered correctly by the browser; essentially, the laxness of the browser is taken advantage of for better minification. These can be turned off via the `Cfg` object. ### Whitespace minify-html has advanced context-aware whitespace minification that does things such as: - Leave whitespace untouched in `pre` and `code`, which are whitespace sensitive. - Trim and collapse whitespace in content tags, as whitespace is collapsed anyway when rendered. - Remove whitespace in layout tags, which allows the use of inline layouts while keeping formatted code. #### Methods There are three whitespace minification methods. When processing text content, minify-html chooses which ones to use depending on the containing element.

Collapse whitespace

> **Applies to:** any element except [whitespace sensitive](./src/spec/tag/whitespace.rs) elements. Reduce a sequence of whitespace characters in text nodes to a single space (U+0020).

Before	After
```html ↵ ··The·quick·brown·fox↵ ··jumps·over·the·lazy↵ ··dog.↵ ```	```html ·The·quick·brown·fox·jumps·over·the·lazy·dog.· ```

Destroy whole whitespace

> **Applies to:** any element except [whitespace sensitive](./src/spec/tag/whitespace.rs), [content](src/spec/tag/whitespace.rs), [content-first](./src/spec/tag/whitespace.rs), and [formatting](./src/spec/tag/whitespace.rs) elements. Remove any text nodes between tags that only consist of whitespace characters.

Before	After
```html ↵ ·· A ↵ ·· B ↵ ·· C ↵ ```	```html ↵ ·· A B C ↵ ```

Trim whitespace

> **Applies to:** any element except [whitespace sensitive](./src/spec/tag/whitespace.rs) and [formatting](./src/spec/tag/whitespace.rs) elements. Remove any leading/trailing whitespace from any leading/trailing text nodes of a tag.

Before	After
```html ↵ ··Hey,·I·just·found↵ ··out·about·this·cool·website!↵ ··^[1]↵ ```	```html Hey,·I·just·found↵ ··out·about·this·cool·website!↵ ··^[1] ```

#### Element types minify-html recognises elements based on one of a few ways it assumes they are used. By making these assumptions, it can apply optimal whitespace minification strategies. |Group|Elements|Expected children| |---|---|---| |Formatting|`a`, `strong`, [and others](./src/spec/tag/whitespace.rs)|Formatting elements, text.| |Content|`h1`, `p`, [and others](src/spec/tag/whitespace.rs)|Formatting elements, text.| |Layout|`div`, `ul`, [and others](./src/spec/tag/whitespace.rs)|Layout elements, content elements.| |Content-first|`label`, `li`, [and others](./src/spec/tag/whitespace.rs)|Like content but could be layout with only one child.|

Formatting elements

> Whitespace is collapsed. Formatting elements are usually inline elements that wrap around part of some text in a content element, so its whitespace isn't trimmed as they're probably part of the content.

Content elements

> Whitespace is trimmed and collapsed. Content elements usually represent a contiguous and complete unit of content such as a paragraph. As such, whitespace is significant but sequences of them are most likely due to formatting. ###### Before ```html

↵ ··Hey,·I·just·found↵ ··out·about·this·cool·website!↵ ··^[1]↵

``` ###### After ```html

Hey,·I·just·found·out·about·this·cool·website!·^[1]

```

Layout elements

> Whitespace is trimmed and collapsed. Whole whitespace is removed. These elements should only contain other elements and no text. This makes it possible to remove whole whitespace, which is useful when using `display: inline-block` so that whitespace between elements (e.g. indentation) does not alter layout and styling. ###### Before ```html

``` ###### After ```html

```

Content-first elements

> Whitespace is trimmed and collapsed. These elements are usually like content elements but are occasionally used like a layout element with one child. Whole whitespace is not removed as it might contain content, but this is OK for using as layout as there is only one child and whitespace is trimmed. ###### Before ```html

↵ ··

↵ ····

↵ ··

↵

``` ###### After ```html

```

### Tags [Optional opening and closing tags](https://html.spec.whatwg.org/multipage/syntax.html#syntax-tag-omission) are removed. ### Attributes Any entities in attribute values are decoded, and then the shortest representation of the value is calculated and used: - Double quoted, with any `"` encoded. - Single quoted, with any `'` encoded. - Unquoted, with `"`/`'` first character (if applicable), any `>`, and any whitespace encoded. Attributes have their whitespace (after any decoding) trimmed and collapsed when possible. [Boolean attribute](https://github.com/wilsonzlin/html-data) values are removed. [Some other attributes](https://github.com/wilsonzlin/html-data) are completely removed if their value is empty or the default value after any processing. `type` attributes on `script` tags with a value equaling a [JavaScript MIME type](https://mimesniff.spec.whatwg.org/#javascript-mime-type) are removed. If an attribute value is empty after any processing, everything but the name is completely removed (i.e. no `=`), as an empty attribute is implicitly [the same](https://html.spec.whatwg.org/multipage/syntax.html#attributes-2) as an attribute with an empty string value. Spaces are removed between attributes when possible. ### Entities Entities are decoded if they're valid and shorter or equal in length when decoded. UTF-8 sequences that have a shorter entity representation are encoded. Numeric entities that do not refer to a valid [Unicode Scalar Value](https://www.unicode.org/glossary/#unicode_scalar_value) are replaced with the [replacement character](https://en.wikipedia.org/wiki/Specials_(Unicode_block)#Replacement_character). Encoding is avoided when possible; for example, `<` are only encoded in content if they are followed by a valid tag name character. If necessary, the shortest entity representation is chosen. ### Comments Comments are removed. ### Ignored Bangs, [processing instructions](https://en.wikipedia.org/wiki/Processing_Instruction), and empty elements are not removed as it is assumed there is a special reason for their declaration. ## Parsing minify-html can process any HTML, handling all possible syntax (including invalid ones) gracefully like browsers. See [Parsing.md](./notes/Parsing.md) for more details. ## Issues and contributions Pull requests and any contributions welcome! If minify-html did something unexpected, misunderstood some syntax, or incorrectly kept/removed some code, [raise an issue](https://github.com/wilsonzlin/minify-html/issues) with some relevant code that can be used to reproduce and investigate the issue.