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UglifyJS Webpack Plugin

This plugin uses uglify-js to minify your JavaScript.

Requirements

This module requires a minimum of Node v6.9.0 and Webpack v4.0.0.

Getting Started

To begin, you'll need to install uglifyjs-webpack-plugin:

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

Then add the plugin to your webpack config. For example:

webpack.config.js

const UglifyJsPlugin = require('uglifyjs-webpack-plugin');

module.exports = {
  optimization: {
    minimizer: [new UglifyJsPlugin()],
  },
};

And run webpack via your preferred method.

Options

`test`

Type: String|RegExp|Array<String|RegExp> Default: /\.js(\?.*)?$/i

Test to match files against.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        test: /\.js(\?.*)?$/i,
      }),
    ],
  },
};

`include`

Type: String|RegExp|Array<String|RegExp> Default: undefined

Files to include.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        include: /\/includes/,
      }),
    ],
  },
};

`exclude`

Type: String|RegExp|Array<String|RegExp> Default: undefined

Files to exclude.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        exclude: /\/excludes/,
      }),
    ],
  },
};

`chunkFilter`

Type: Function<(chunk) -> boolean> Default: () => true

Allowing to filter which chunks should be uglified (by default all chunks are uglified). Return true to uglify the chunk, false otherwise.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        chunkFilter: (chunk) => {
          // Exclude uglification for the `vendor` chunk
          if (chunk.name === 'vendor') {
            return false;
          }
          
          return true;
        }
      }),
    ],
  },
};

`cache`

Type: Boolean|String Default: false

Enable file caching. Default path to cache directory: node_modules/.cache/uglifyjs-webpack-plugin.

ℹ️ If you use your own minify function please read the minify section for cache invalidation correctly.

`Boolean`

Enable/disable file caching.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        cache: true,
      }),
    ],
  },
};

`String`

Enable file caching and set path to cache directory.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        cache: 'path/to/cache',
      }),
    ],
  },
};

`cacheKeys`

Type: Function<(defaultCacheKeys, file) -> Object> Default: defaultCacheKeys => defaultCacheKeys

Allows you to override default cache keys.

Default cache keys:

({
  'uglify-js': require('uglify-js/package.json').version, // uglify version
  'uglifyjs-webpack-plugin': require('../package.json').version, // plugin version
  'uglifyjs-webpack-plugin-options': this.options, // plugin options
  path: compiler.outputPath ? `${compiler.outputPath}/${file}` : file, // asset path
  hash: crypto
    .createHash('md4')
    .update(input)
    .digest('hex'), // source file hash
});

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        cache: true,
        cacheKeys: (defaultCacheKeys, file) => {
          defaultCacheKeys.myCacheKey = 'myCacheKeyValue';

          return defaultCacheKeys;
        },
      }),
    ],
  },
};

`parallel`

Type: Boolean|Number Default: false

Use multi-process parallel running to improve the build speed. Default number of concurrent runs: os.cpus().length - 1.

ℹ️ Parallelization can speedup your build significantly and is therefore highly recommended.

`Boolean`

Enable/disable multi-process parallel running.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        parallel: true,
      }),
    ],
  },
};

`Number`

Enable multi-process parallel running and set number of concurrent runs.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        parallel: 4,
      }),
    ],
  },
};

`sourceMap`

Type: Boolean Default: false

Use source maps to map error message locations to modules (this slows down the compilation). If you use your own minify function please read the minify section for handling source maps correctly.

⚠️ cheap-source-map options don't work with this plugin.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        sourceMap: true,
      }),
    ],
  },
};

`minify`

Type: Function Default: undefined

Allows you to override default minify function. By default plugin uses uglify-js package. Useful for using and testing unpublished versions or forks.

⚠️ Always use require inside minify function when parallel option enabled.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        minify(file, sourceMap) {
          const extractedComments = [];

          // Custom logic for extract comments

          const { error, map, code, warnings } = require('uglify-module') // Or require('./path/to/uglify-module')
            .minify(file, {
              /* Your options for minification */
            });

          return { error, map, code, warnings, extractedComments };
        },
      }),
    ],
  },
};

`uglifyOptions`

Type: Object Default: default

UglifyJS minify options.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        uglifyOptions: {
          warnings: false,
          parse: {},
          compress: {},
          mangle: true, // Note `mangle.properties` is `false` by default.
          output: null,
          toplevel: false,
          nameCache: null,
          ie8: false,
          keep_fnames: false,
        },
      }),
    ],
  },
};

`extractComments`

Type: Boolean|String|RegExp|Function<(node, comment) -> Boolean|Object> Default: false

Whether comments shall be extracted to a separate file, (see details). By default extract only comments using /^\**!|@preserve|@license|@cc_on/i regexp condition and remove remaining comments. If the original file is named foo.js, then the comments will be stored to foo.js.LICENSE. The uglifyOptions.output.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.

`Boolean`

Enable/disable extracting comments.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        extractComments: true,
      }),
    ],
  },
};

`String`

Extract all or some (use /^\**!|@preserve|@license|@cc_on/i RegExp) comments.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        extractComments: 'all',
      }),
    ],
  },
};

`RegExp`

All comments that match the given expression will be extracted to the separate file.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        extractComments: /@extract/i,
      }),
    ],
  },
};

`Function<(node, comment) -> Boolean>`

All comments that match the given expression will be extracted to the separate file.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        extractComments: function(astNode, comment) {
          if (/@extract/i.test(comment.value)) {
            return true;
          }

          return false;
        },
      }),
    ],
  },
};

`Object`

Allow to customize condition for extract comments, specify extracted file name and banner.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        extractComments: {
          condition: /^\**!|@preserve|@license|@cc_on/i,
          filename(file) {
            return `${file}.LICENSE`;
          },
          banner(licenseFile) {
            return `License information can be found in ${licenseFile}`;
          },
        },
      }),
    ],
  },
};

`condition`

Type: Boolean|String|RegExp|Function<(node, comment) -> Boolean|Object>

Condition what comments you need extract.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        extractComments: {
          condition: 'some',
          filename(file) {
            return `${file}.LICENSE`;
          },
          banner(licenseFile) {
            return `License information can be found in ${licenseFile}`;
          },
        },
      }),
    ],
  },
};

`filename`

Type: Regex|Function<(string) -> String> Default: ${file}.LICENSE

The file where the extracted comments will be stored. Default is to append the suffix .LICENSE to the original filename.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        extractComments: {
          condition: /^\**!|@preserve|@license|@cc_on/i,
          filename: 'extracted-comments.js',
          banner(licenseFile) {
            return `License information can be found in ${licenseFile}`;
          },
        },
      }),
    ],
  },
};

`banner`

Type: Boolean|String|Function<(string) -> String> Default: /*! For license information please see ${commentsFile} */

The banner text that points to the extracted file and will be added on top of 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.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        extractComments: {
          condition: true,
          filename(file) {
            return `${file}.LICENSE`;
          },
          banner(commentsFile) {
            return `My custom banner about license information ${commentsFile}`;
          },
        },
      }),
    ],
  },
};

`warningsFilter`

Type: Function<(warning, source) -> Boolean> Default: () => true

Allow to filter uglify-js warnings. Return true to keep the warning, false otherwise.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        warningsFilter: (warning, source) => {
          if (/Dropping unreachable code/i.test(warning)) {
            return true;
          }

          if (/filename\.js/i.test(source)) {
            return true;
          }

          return false;
        },
      }),
    ],
  },
};

Examples

Cache And Parallel

Enable cache and multi-process parallel running.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        cache: true,
        parallel: true,
      }),
    ],
  },
};

Preserve Comments

Extract all legal comments (i.e. /^\**!|@preserve|@license|@cc_on/i) and preserve /@license/i comments.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        uglifyOptions: {
          output: {
            comments: /@license/i,
          },
        },
        extractComments: true,
      }),
    ],
  },
};

Remove Comments

If you avoid building with comments, set uglifyOptions.output.comments to false as in this config:

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        uglifyOptions: {
          output: {
            comments: false,
          },
        },
      }),
    ],
  },
};

Custom Minify Function

Override default minify function - use terser for minification.

webpack.config.js

module.exports = {
  optimization: {
    minimizer: [
      new UglifyJsPlugin({
        // Uncomment lines below for cache invalidation correctly
        // cache: true,
        // cacheKeys(defaultCacheKeys) {
        //   delete defaultCacheKeys['uglify-js'];
        //
        //   return Object.assign(
        //     {},
        //     defaultCacheKeys,
        //     { 'uglify-js': require('uglify-js/package.json').version },
        //   );
        // },
        minify(file, sourceMap) {
          // https://github.com/mishoo/UglifyJS2#minify-options
          const uglifyJsOptions = {
            /* your `uglify-js` package options */
          };

          if (sourceMap) {
            uglifyJsOptions.sourceMap = {
              content: sourceMap,
            };
          }

          return require('terser').minify(file, uglifyJsOptions);
        },
      }),
    ],
  },
};

Contributing

Please take a moment to read our contributing guidelines if you haven't yet done so.

CONTRIBUTING

License

MIT

License

webpack-contrib/uglifyjs-webpack-plugin

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