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terser-webpack-plugin

This plugin uses terser to minify your JavaScript.


Getting Started

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

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


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

webpack.config.js

const TerserPlugin = require('terser-webpack-plugin');

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


And run webpack via your preferred method.


Options


test


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

Test to match files against.

webpack.config.js

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


include


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

Files to include.

webpack.config.js

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


exclude


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

Files to exclude.

webpack.config.js

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


cache


⚠ Ignored in webpack 5! Please use https://webpack.js.org/configuration/other-options/#cache.


Type: Boolean|String
Default: true

Enable file caching.
Default path to cache directory: node_modules/.cache/terser-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: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        cache: true,
      }),
    ],
  },
};


String


Enable file caching and set path to cache directory.

webpack.config.js

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


cacheKeys


⚠ Ignored in webpack 5! Please use https://webpack.js.org/configuration/other-options/#cache.


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

Allows you to override default cache keys.

Default cache keys:

({
  terser: require('terser/package.json').version, // terser version
  'terser-webpack-plugin': require('../package.json').version, // plugin version
  'terser-webpack-plugin-options': this.options, // plugin options
  nodeVersion: process.version, // Node.js version
  name: file, // asset path
  contentHash: crypto.createHash('md4').update(input).digest('hex'), // source file hash
});


webpack.config.js

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

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


parallel


Type: Boolean|Number
Default: true

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.

⚠️ If you use Circle CI or any other environment that doesn't provide real available count of CPUs then you need to setup explicitly number of CPUs to avoid Error: Call retries were exceeded (see #143, #202).


Boolean


Enable/disable multi-process parallel running.

webpack.config.js

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


Number


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

webpack.config.js

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


sourceMap


Type: Boolean
Default: false (see below for details around devtool value and SourceMapDevToolPlugin plugin)

Works only with source-map, inline-source-map, hidden-source-map and nosources-source-map values for the devtool option.

Why?


eval wraps modules in eval("string") and the minimizer does not handle strings.

cheap has not column information and minimizer generate only a single line, which leave only a single mapping.


The plugin respect the devtool and using the SourceMapDevToolPlugin plugin.
Using supported devtool values enable source map generation.
Using SourceMapDevToolPlugin with enabled the columns option enables source map generation.

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.

webpack.config.js

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


minify


Type: Function
Default: undefined

Allows you to override default minify function.
By default plugin uses terser 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: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        terserOptions: {
          myCustomOption: true,
        },
        // Can be async
        minify: (file, sourceMap, minimizerOptions) => {
          // The `minimizerOptions` option contains option from the `terserOptions` option
          // You can use `minimizerOptions.myCustomOption`
          const extractedComments = [];

          // Custom logic for extract comments

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

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


terserOptions


Type: Object
Default: default

Terser minify options.

webpack.config.js

module.exports = {
  optimization: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        terserOptions: {
          ecma: undefined,
          parse: {},
          compress: {},
          mangle: true, // Note `mangle.properties` is `false` by default.
          module: false,
          output: null,
          toplevel: false,
          nameCache: null,
          ie8: false,
          keep_classnames: undefined,
          keep_fnames: false,
          safari10: false,
        },
      }),
    ],
  },
};


extractComments


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

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.txt.
The terserOptions.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: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        extractComments: true,
      }),
    ],
  },
};


String


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

webpack.config.js

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


RegExp


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

webpack.config.js

module.exports = {
  optimization: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        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: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        extractComments: (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: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        extractComments: {
          condition: /^\**!|@preserve|@license|@cc_on/i,
          filename: (fileData) => {
            // The "fileData" argument contains object with "filename", "basename", "query" and "hash"
            return `${fileData.filename}.LICENSE.txt${fileData.query}`;
          },
          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: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        extractComments: {
          condition: 'some',
          filename: (fileData) => {
            // The "fileData" argument contains object with "filename", "basename", "query" and "hash"
            return `${fileData.filename}.LICENSE.txt${fileData.query}`;
          },
          banner: (licenseFile) => {
            return `License information can be found in ${licenseFile}`;
          },
        },
      }),
    ],
  },
};


filename


Type: String|Function<(string) -> String>
Default: [file].LICENSE.txt[query]

Available placeholders: [file], [query] and [filebase] ([base] for webpack 5).

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


⚠️ We highly recommend using the txt extension. Using js/cjs/mjs extensions may conflict with existing assets which leads to broken code.


webpack.config.js

module.exports = {
  optimization: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        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: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        extractComments: {
          condition: true,
          filename: (fileData) => {
            // The "fileData" argument contains object with "filename", "basename", "query" and "hash"
            return `${fileData.filename}.LICENSE.txt${fileData.query}`;
          },
          banner: (commentsFile) => {
            return `My custom banner about license information ${commentsFile}`;
          },
        },
      }),
    ],
  },
};


Examples


Preserve Comments

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

webpack.config.js

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


Remove Comments

If you avoid building with comments, use this config:

webpack.config.js

module.exports = {
  optimization: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        terserOptions: {
          output: {
            comments: false,
          },
        },
        extractComments: false,
      }),
    ],
  },
};


Custom Minify Function

Override default minify function - use uglify-js for minification.

webpack.config.js

module.exports = {
  optimization: {
    minimize: true,
    minimizer: [
      new TerserPlugin({
        // Uncomment lines below for cache invalidation correctly
        // cache: true,
        // cacheKeys: (defaultCacheKeys) => {
        //   delete defaultCacheKeys.terser;
        //
        //   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('uglify-js').minify(file, uglifyJsOptions);
        },
      }),
    ],
  },
};


Contributing

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

CONTRIBUTING


License

MIT