Awesome Open Source
Awesome Open Source


This project is deprecated in favor of official Webpack plugin webpack-contrib/closure-webpack-plugin


Google Closure Compiler plugin for Webpack

Webpack Closure Compiler Plugin

Table of Contents

Why use Closure Compiler instead of UglifyJS?

Closure Compiler is the most advanced JavaScript optimization tool. It generates smallest bundle and emits efficient JavaScript code by doing whole program analysis and optimization, removing closures and inlining function calls, as well as tree-shaking for AMD, CommonJS and ES2015 modules.


npm i -D webpack-closure-compiler


While there's JavaScript version of Closure Compiler, the original compiler is written in Java and thus Java version is more complete and performs better in terms of JavaScript code optimizations and compilation speed. If you want to use Java-based compiler, make sure you have installed Java SDK.



compiler: <Object>

A hash of options to pass to google-closure-compiler.

You can optionally specify a path to your own version of the compiler.jar if the version provided by the plugin isn't working for you. See example below for optional parameter.

jsCompiler: <Boolean>

Use pure JavaScript version of Closure Compiler (no Java dependency). Note that compilation time will be around 2x slower. Default is false. concurrency and jsCompiler options are mutually exclusive.

concurrency: <Number>

The maximum number of compiler instances to run in parallel, defaults to 1. concurrency and jsCompiler options are mutually exclusive.

test: <RegExp>

Process only files which filename satisfies specified RegExp, defaults to /\.js($|\?)/i.


const path = require('path');
const ClosureCompilerPlugin = require('webpack-closure-compiler');

module.exports = {
    entry: [
        path.join(__dirname, 'app.js')
    output: {
        path: path.join(__dirname, '/'),
        filename: 'app.min.js'
    plugins: [
        new ClosureCompilerPlugin({
          compiler: {
            jar: 'path/to/your/custom/compiler.jar', //optional
            language_in: 'ECMASCRIPT6',
            language_out: 'ECMASCRIPT5',
            compilation_level: 'ADVANCED'
          concurrency: 3,


Read Closure Compiler Handbook to you understand how to use Closure Compiler and learn its features.


If you've spotted a bug, please, open an issue, and after discussion submit a pull request with a bug fix. If you would like to add a feature or change existing behaviour, open an issue and tell about what exactly you want to change/add.



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