diff --git a/Cargo.toml b/Cargo.toml
index 7ec748e..00986ee 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,10 +17,11 @@ maintenance = { status = "actively-developed" }
 
 [features]
 default = []
-js-esbuild = ["esbuild-rs"]
+js-esbuild = ["crossbeam", "esbuild-rs"]
 
 [dependencies]
-esbuild-rs = { version = "0.0.5", optional = true }
+crossbeam = { version = "0.7.3", optional = true }
+esbuild-rs = { version = "0.1.2", optional = true }
 lazy_static = "1.4.0"
 memchr = "2.3.3"
 
diff --git a/README.md b/README.md
index 339f8cf..36a8370 100644
--- a/README.md
+++ b/README.md
@@ -99,7 +99,7 @@ fn main() {
 <details>
 <summary><strong>Node.js</strong></summary>
 
-- Package: [@minify-html/js-esbuild](https://www.npmjs.com/package/@minify-html/js-esbuild)
+- Package: [@minify-html/js](https://www.npmjs.com/package/@minify-html/js)
 - Binding: [Neon](https://neon-bindings.com/)
 - Platforms: macOS, Linux; Node.js 8 and higher
 
@@ -108,19 +108,19 @@ fn main() {
 Using npm:
 
 ```bash
-npm i @minify-html/js-esbuild
+npm i @minify-html/js
 ```
 
 Using Yarn:
 
 ```bash
-yarn add @minify-html/js-esbuild
+yarn add @minify-html/js
 ```
 
 ##### Use
 
 ```js
-const minifyHtml = require("@minify-html/js-esbuild");
+const minifyHtml = require("@minify-html/js");
 
 const cfg = { minifyJs: false };
 const minified = minifyHtml.minify("<p>  Hello, world!  </p>", cfg);
@@ -134,7 +134,7 @@ const minified = minifyHtml.minifyInPlace(source, cfg);
 minify-html is also available for TypeScript:
 
 ```ts
-import * as minifyHtml from "@minify-html/js-esbuild";
+import * as minifyHtml from "@minify-html/js";
 import * as fs from "fs";
 
 const cfg = { minifyJs: false };
diff --git a/bench/minifiers.js b/bench/minifiers.js
index 7d1ae92..3d496e7 100644
--- a/bench/minifiers.js
+++ b/bench/minifiers.js
@@ -1,5 +1,5 @@
 const htmlMinifier = require("html-minifier");
-const minifyHtml = require("@minify-html/js-esbuild");
+const minifyHtml = require("@minify-html/js");
 const minimize = require("minimize");
 const terser = require('terser');
 
diff --git a/bench/package.json b/bench/package.json
index d0c2674..2541ffb 100644
--- a/bench/package.json
+++ b/bench/package.json
@@ -1,7 +1,7 @@
 {
   "private": true,
   "dependencies": {
-    "@minify-html/js-esbuild": "file:../nodejs",
+    "@minify-html/js": "file:../nodejs",
     "benchmark": "2.1.4",
     "chart.js": "^2.9.3",
     "chartjs-node": "^1.7.1",
diff --git a/src/err.rs b/src/err.rs
index b91b496..4267e05 100644
--- a/src/err.rs
+++ b/src/err.rs
@@ -22,4 +22,17 @@ impl ErrorType {
     }
 }
 
+#[derive(Debug)]
+pub struct Error {
+    pub error_type: ErrorType,
+    pub position: usize,
+}
+
+#[derive(Debug)]
+pub struct FriendlyError {
+    pub position: usize,
+    pub message: String,
+    pub code_context: String,
+}
+
 pub type ProcessingResult<T> = Result<T, ErrorType>;
diff --git a/src/lib.rs b/src/lib.rs
index 2ca27fd..41464c2 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,4 @@
-pub use crate::err::ErrorType as ErrorType;
+pub use crate::err::{Error, ErrorType, FriendlyError};
 use crate::proc::Processor;
 use crate::unit::content::process_content;
 use crate::spec::tag::ns::Namespace;
@@ -14,15 +14,18 @@ mod spec;
 mod tests;
 mod unit;
 
-pub fn in_place(code: &mut [u8], cfg: &Cfg) -> Result<usize, (ErrorType, usize)> {
+pub fn in_place(code: &mut [u8], cfg: &Cfg) -> Result<usize, Error> {
     let mut proc = Processor::new(code);
     match process_content(&mut proc, cfg, Namespace::Html, None) {
-        Ok(()) => Ok(proc.written_len()),
-        Err(e) => Err((e, proc.read_len())),
+        Ok(()) => Ok(proc.finish()),
+        Err(e) => Err(Error {
+            error_type: e,
+            position: proc.read_len(),
+        }),
     }
 }
 
-pub fn in_place_str<'s>(code: &'s mut str, cfg: &Cfg) -> Result<&'s str, (ErrorType, usize)> {
+pub fn in_place_str<'s>(code: &'s mut str, cfg: &Cfg) -> Result<&'s str, Error> {
     let bytes = unsafe { code.as_bytes_mut() };
     match in_place(bytes, cfg) {
         Ok(min_len) => Ok(unsafe { std::str::from_utf8_unchecked(&bytes[..min_len]) }),
@@ -30,7 +33,7 @@ pub fn in_place_str<'s>(code: &'s mut str, cfg: &Cfg) -> Result<&'s str, (ErrorT
     }
 }
 
-pub fn truncate(code: &mut Vec<u8>, cfg: &Cfg) -> Result<(), (ErrorType, usize)> {
+pub fn truncate(code: &mut Vec<u8>, cfg: &Cfg) -> Result<(), Error> {
     match in_place(code, cfg) {
         Ok(written_len) => {
             code.truncate(written_len);
@@ -40,7 +43,7 @@ pub fn truncate(code: &mut Vec<u8>, cfg: &Cfg) -> Result<(), (ErrorType, usize)>
     }
 }
 
-pub fn copy(code: &[u8], cfg: &Cfg) -> Result<Vec<u8>, (ErrorType, usize)> {
+pub fn copy(code: &[u8], cfg: &Cfg) -> Result<Vec<u8>, Error> {
     let mut copy = code.to_vec();
     match truncate(&mut copy, cfg) {
         Ok(()) => Ok(copy),
@@ -48,17 +51,10 @@ pub fn copy(code: &[u8], cfg: &Cfg) -> Result<Vec<u8>, (ErrorType, usize)> {
     }
 }
 
-pub struct FriendlyError {
-    // Make public to allow destructuring.
-    pub position: usize,
-    pub message: String,
-    pub code_context: String,
-}
-
 pub fn with_friendly_error(code: &mut [u8], cfg: &Cfg) -> Result<usize, FriendlyError> {
     let mut proc = Processor::new(code);
     match process_content(&mut proc, cfg, Namespace::Html, None) {
-        Ok(()) => Ok(proc.written_len()),
+        Ok(()) => Ok(proc.finish()),
         Err(e) => Err(FriendlyError {
             position: proc.read_len(),
             message: e.message(),
diff --git a/src/proc/mod.rs b/src/proc/mod.rs
index fcb6ed3..9cb2b3a 100644
--- a/src/proc/mod.rs
+++ b/src/proc/mod.rs
@@ -8,6 +8,9 @@ use crate::proc::MatchMode::*;
 use crate::proc::range::ProcessorRange;
 use memchr::memchr;
 use crate::gen::codepoints::{WHITESPACE, Lookup};
+use std::sync::{Arc, Mutex};
+use esbuild_rs::TransformResult;
+use crossbeam::sync::WaitGroup;
 
 pub mod checkpoint;
 pub mod entity;
@@ -39,6 +42,11 @@ pub enum MatchAction {
     MatchOnly,
 }
 
+pub struct JsMinSection {
+    pub src_range: ProcessorRange,
+    pub result: TransformResult,
+}
+
 // Processing state of a file. Single use only; create one per processing.
 pub struct Processor<'d> {
     code: &'d mut [u8],
@@ -46,6 +54,10 @@ pub struct Processor<'d> {
     read_next: usize,
     // Index of the next unwritten space.
     write_next: usize,
+    #[cfg(feature = "js-esbuild")]
+    script_wg: WaitGroup,
+    #[cfg(feature = "js-esbuild")]
+    script_results: Arc<Mutex<Vec<JsMinSection>>>,
 }
 
 impl<'d> Index<ProcessorRange> for Processor<'d> {
@@ -66,7 +78,15 @@ impl<'d> IndexMut<ProcessorRange> for Processor<'d> {
 impl<'d> Processor<'d> {
     // Constructor.
     pub fn new(code: &mut [u8]) -> Processor {
-        Processor { write_next: 0, read_next: 0, code }
+        Processor {
+            write_next: 0,
+            read_next: 0,
+            code,
+            #[cfg(feature = "js-esbuild")]
+            script_wg: WaitGroup::new(),
+            #[cfg(feature = "js-esbuild")]
+            script_results: Arc::new(Mutex::new(Vec::new())),
+        }
     }
 
     // INTERNAL APIs.
@@ -194,11 +214,6 @@ impl<'d> Processor<'d> {
         self.read_next
     }
 
-    /// Get how many characters have been written to output.
-    pub fn written_len(&self) -> usize {
-        self.write_next
-    }
-
     pub fn reserve_output(&mut self, amount: usize) -> () {
         self.write_next += amount;
     }
@@ -288,6 +303,34 @@ impl<'d> Processor<'d> {
         debug_assert!(self._in_bounds(count - 1));
         self._shift(count);
     }
+
+    pub fn new_script_section(&self) -> (WaitGroup, Arc<Mutex<Vec<JsMinSection>>>) {
+        (self.script_wg.clone(), self.script_results.clone())
+    }
+
+    pub fn finish(self) -> usize {
+        debug_assert!(self.at_end());
+        self.script_wg.wait();
+        let mut results = Arc::try_unwrap(self.script_results)
+            .unwrap_or_else(|_| panic!("failed to acquire script results"))
+            .into_inner()
+            .unwrap();
+        if !results.is_empty() {
+            results.sort_unstable_by_key(|r| r.src_range.start);
+            let mut write_start = results[0].src_range.start;
+            for (i, res) in results.iter().enumerate() {
+                let min_code = res.result.js.trim();
+                if min_code.len() < res.src_range.len() {
+                    let write_end = write_start + min_code.len();
+                    self.code[write_start..write_end].copy_from_slice(min_code.as_bytes());
+                    let next_start = results.get(i + 1).map_or(self.write_next, |r| r.src_range.start);
+                    self.code.copy_within(res.src_range.end..next_start, write_end);
+                    write_start = write_end + (next_start - res.src_range.end);
+                };
+            };
+        };
+        self.write_next
+    }
 }
 
 impl Debug for Processor<'_> {
diff --git a/src/unit/script.rs b/src/unit/script.rs
index acbf67f..c0fa673 100644
--- a/src/unit/script.rs
+++ b/src/unit/script.rs
@@ -1,10 +1,23 @@
 use crate::err::ProcessingResult;
 use crate::proc::MatchAction::*;
 use crate::proc::MatchMode::*;
-use crate::proc::Processor;
+use crate::proc::{Processor, JsMinSection};
 use crate::cfg::Cfg;
 #[cfg(feature = "js-esbuild")]
 use crate::proc::checkpoint::Checkpoint;
+use esbuild_rs::{TransformOptionsBuilder, TransformOptions};
+use std::sync::Arc;
+use lazy_static::lazy_static;
+
+lazy_static! {
+    static ref TRANSFORM_OPTIONS: Arc<TransformOptions> = {
+        let mut builder = TransformOptionsBuilder::new();
+        builder.minify_identifiers = true;
+        builder.minify_syntax = true;
+        builder.minify_whitespace = true;
+        builder.build()
+    };
+}
 
 pub fn process_script(proc: &mut Processor, cfg: &Cfg) -> ProcessingResult<()> {
     #[cfg(feature = "js-esbuild")]
@@ -17,17 +30,18 @@ pub fn process_script(proc: &mut Processor, cfg: &Cfg) -> ProcessingResult<()> {
         if proc.m(IsSeq(b"</script"), MatchOnly).nonempty() {
             #[cfg(feature = "js-esbuild")]
             if cfg.minify_js {
+                let (wg, results) = proc.new_script_section();
                 let src_range = start.written_range(proc);
-                let src = unsafe {
-                    std::string::String::from_utf8_unchecked(proc[src_range].to_vec())
-                };
-                let min = esbuild_rs::esbuild(&src).trim().as_bytes();
-                // `src.len()` is amount of bytes, so this is guaranteed to not overwrite.
-                if min.len() < src.len() {
-                    start.erase_written(proc);
-                    proc.write_slice(min);
-                    return Ok(());
-                };
+                // TODO Optimise: Avoid copying to new Vec.
+                let src = Arc::new(proc[src_range].to_vec());
+                esbuild_rs::transform(src, TRANSFORM_OPTIONS.clone(), move |result| {
+                    results.lock().unwrap().push(JsMinSection {
+                        src_range,
+                        result,
+                    });
+                    drop(wg);
+                });
+                return Ok(());
             };
             break;
         };