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UglifyJS Webpack Plugin

This plugin uses UglifyJS v2 to minify your JavaScript.

Note that webpack contains the same plugin under webpack.optimize.UglifyJsPlugin. This is a standalone version for those that want to control the version of UglifyJS. The documentation is valid apart from the installation instructions in that case.


With Yarn:

yarn add uglifyjs-webpack-plugin --dev

With npm:

npm install uglifyjs-webpack-plugin --save-dev

Important! The plugin has a peer dependency to uglify-js, so in order to use the plugin, also uglify-js has to be installed. The currently (2017/1/25) available uglify-js npm packages; however, do not support minification of ES6 code. In order to support ES6, an ES6-capable, a.k.a. harmony, version of UglifyJS has to be provided.

If your minification target is ES6:

yarn add git:// --dev

If your minification target is ES5:

yarn add uglify-js --dev


const UglifyJSPlugin = require('uglifyjs-webpack-plugin');
module.exports = {
  entry: {...},
  output: {...},
  module: {...},
  plugins: [
    new UglifyJSPlugin()


This plugin supports UglifyJS features as discussed below:

Property Type Default Description
compress boolean, object true See UglifyJS documentation.
mangle boolean, object true See below.
beautify boolean false Beautify output.
output An object providing options for UglifyJS OutputStream Lower level access to UglifyJS output.
comments boolean, RegExp, function(astNode, comment) -> boolean Defaults to preserving comments containing /*!, /**!, @preserve or @license. Comment related configuration.
extractComments boolean, RegExp, function (astNode, comment) -> boolean, object false Whether comments shall be extracted to a separate file, (see details, since webpack 2.3.0)
sourceMap boolean false Use SourceMaps to map error message locations to modules. This slows down the compilation. Important! cheap source map options don't work with the plugin!
test RegExp, Array /.js($|?)/i Test to match files against.
include RegExp, Array Test only include files.
exclude RegExp, Array Files to exclude from testing.
warningsFilter function(source) -> boolean Allow to filter uglify warnings (since webpack 2.3.0)


mangle (boolean|object) - Passing true or an object enables and provides options for UglifyJS name mangling. See UglifyJS documentation for mangle options. Example configuration, this will not mangle properties (see below):

new UglifyJsPlugin({
  mangle: {
    // Skip mangling these 
    except: ['$super', '$', 'exports', 'require']

mangle.props (boolean|object) - Passing true or an object enables and provides options for UglifyJS property mangling - see UglifyJS documentation for mangleProperties options.

Note: the UglifyJS docs warn that you will probably break your source if you use property mangling, so if you aren’t sure why you’d need this feature, you most likely shouldn’t be using it! This is not enabled by default.

Example configuration, this will mangle both names and properties:

new UglifyJsPlugin({
  mangle: {
    props: true

Extracting Comments

The extractComments option can be

  • true: All comments that normally would be preserved by the comments option will be moved to a separate file. If the original file is named foo.js, then the comments will be stored to foo.js.LICENSE
  • regular expression (given as RegExp or string) or a function (astNode, comment) -> boolean: All comments that match the given expression (resp. are evaluated to true by the function) will be extracted to the separate file. The comments option specifies whether the comment will be preserved, i.e. it is possible to preserve some comments (e.g. annotations) while extracting others or even preserving comments that have been extracted.
  • an object consisting of the following keys, all optional:
    • condition: regular expression or function (see previous point)
    • filename: The file where the extracted comments will be stored. Can be either a string or function (string) -> string which will be given the original filename. Default is to append the suffix .LICENSE to the original filename.
    • banner: The banner text that points to the extracted file and will be added on top of the original file. will be added to the original file. Can be false (no banner), a string, or a function (string) -> string that will be called with the filename where extracted comments have been stored. Will be wrapped into comment. Default: /*! For license information please see foo.js.LICENSE */


Juho Vepsäläinen

Joshua Wiens

Kees Kluskens

Sean Larkin