README

# terser-webpack-plugin

This plugin uses terser to minify your JavaScript.

> ℹ️ For `webpack@3` use terser-webpack-plugin-legacy package

## 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: {
minimizer: [new TerserPlugin()],
},
};

And run `webpack` via your preferred method.

## Options

### <tt>test</tt>

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

Test to match files against.

webpack.config.js

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

### <tt>include</tt>

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

Files to include.

webpack.config.js

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

### <tt>exclude</tt>

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

Files to exclude.

webpack.config.js

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

### <tt>chunkFilter</tt>

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 TerserPlugin({
chunkFilter: (chunk) => {
// Exclude uglification for the `vendor` chunk
if (chunk.name === 'vendor') {
return false;
}
return true;
},
}),
],
},
};

### <tt>cache</tt>

Type: `Boolean|String` Default: `false`

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.

#### <tt>Boolean</tt>

Enable/disable file caching.

webpack.config.js

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

#### <tt>String</tt>

Enable file caching and set path to cache directory.

webpack.config.js

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

### <tt>cacheKeys</tt>

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
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 TerserPlugin({
cache: true,
cacheKeys: (defaultCacheKeys, file) => {
defaultCacheKeys.myCacheKey = 'myCacheKeyValue';
return defaultCacheKeys;
},
}),
],
},
};

### <tt>parallel</tt>

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.

#### <tt>Boolean</tt>

Enable/disable multi-process parallel running.

webpack.config.js

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

#### <tt>Number</tt>

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

webpack.config.js

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

### <tt>sourceMap</tt>

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 TerserPlugin({
sourceMap: true,
}),
],
},
};

### <tt>minify</tt>

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: {
minimizer: [
new TerserPlugin({
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 };
},
}),
],
},
};

### <tt>terserOptions</tt>

Type: `Object` Default: default

Terser minify options.

webpack.config.js

module.exports = {
optimization: {
minimizer: [
new TerserPlugin({
terserOptions: {
ecma: undefined,
warnings: false,
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,
},
}),
],
},
};

### <tt>extractComments</tt>

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

#### <tt>Boolean</tt>

Enable/disable extracting comments.

webpack.config.js

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

#### <tt>String</tt>

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

webpack.config.js

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

#### <tt>RegExp</tt>

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

webpack.config.js

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

#### <tt>Function<(node, comment) -> Boolean></tt>

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

webpack.config.js

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

#### <tt>Object</tt>

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

webpack.config.js

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

##### `filename`

Type: `String|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 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: {
minimizer: [
new TerserPlugin({
extractComments: {
condition: true,
filename: (file) => {
return `${file}.LICENSE`;
},
banner: (commentsFile) => {
return `My custom banner about license information ${commentsFile}`;
},
},
}),
],
},
};

### <tt>warningsFilter</tt>

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

Allow to filter terser warnings. Return `true` to keep the warning, `false` otherwise.

webpack.config.js

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

### Remove Comments

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

webpack.config.js

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

### Custom Minify Function

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

webpack.config.js

module.exports = {
optimization: {
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.

./.github/CONTRIBUTING.md "CONTRIBUTING"

## License

MIT