terser-webpack-plugin
Advanced tools
The terser-webpack-plugin is a plugin for webpack that uses Terser to minify JavaScript files. It can improve the performance of web applications by reducing the size of the JavaScript bundle, which decreases loading times for users. It also offers options for code compression, mangling, and potentially other optimizations that can be configured to suit various deployment needs.
Minification
This feature allows you to minify your JavaScript files, removing unnecessary whitespace, comments, and code. It helps in reducing the file size and improving load times for your web application.
const TerserPlugin = require('terser-webpack-plugin');
module.exports = {
optimization: {
minimize: true,
minimizer: [new TerserPlugin()],
},
};Source Map Support
This feature enables the generation of source maps, which help in debugging minified JavaScript by mapping the minified code back to the original source code.
const TerserPlugin = require('terser-webpack-plugin');
module.exports = {
optimization: {
minimize: true,
minimizer: [new TerserPlugin({
sourceMap: true,
})],
},
};Code Compression
This feature allows for further compression of the JavaScript code, such as removing console logs and other statements that are not needed in production code.
const TerserPlugin = require('terser-webpack-plugin');
module.exports = {
optimization: {
minimize: true,
minimizer: [new TerserPlugin({
terserOptions: {
compress: {
drop_console: true,
},
},
})],
},
};Mangling
Mangling reduces the size of your code by shortening the names of variables and functions to single characters. This feature is particularly useful for reducing the size of large codebases.
const TerserPlugin = require('terser-webpack-plugin');
module.exports = {
optimization: {
minimize: true,
minimizer: [new TerserPlugin({
terserOptions: {
mangle: true, // Note: `mangle` is `true` by default.
},
})],
},
};This package is similar to terser-webpack-plugin as it also minifies JavaScript files. However, it uses UglifyJS for minification instead of Terser. Terser is a fork of UglifyJS with ES6+ support, so terser-webpack-plugin might be more suitable for projects using modern JavaScript features.
This plugin uses babel-minify for minifying JavaScript. It is similar to terser-webpack-plugin but leverages the Babel toolchain. It might be a better choice for projects that are already using Babel for JavaScript transpilation.
Closure-webpack-plugin uses Google's Closure Compiler for minifying JavaScript, which is known for its advanced optimizations. It can be more aggressive in optimization compared to terser-webpack-plugin, but it may also require more configuration and might not support all modern JavaScript features as well as Terser.
This plugin uses terser to minify your JavaScript.
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.
testType: 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,
}),
],
},
};
includeType: String|RegExp|Array<String|RegExp>
Default: undefined
Files to include.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
include: /\/includes/,
}),
],
},
};
excludeType: 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
minifyfunction please read theminifysection for cache invalidation correctly.
BooleanEnable/disable file caching.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
cache: true,
}),
],
},
};
StringEnable 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
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: {
minimize: true,
minimizer: [
new TerserPlugin({
cache: true,
cacheKeys: (defaultCacheKeys, file) => {
defaultCacheKeys.myCacheKey = 'myCacheKeyValue';
return defaultCacheKeys;
},
}),
],
},
};
parallelType: 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).
BooleanEnable/disable multi-process parallel running.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
parallel: true,
}),
],
},
};
NumberEnable multi-process parallel running and set number of concurrent runs.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
parallel: 4,
}),
],
},
};
sourceMapType: 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,
}),
],
},
};
minifyType: 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
requireinsideminifyfunction whenparalleloption enabled.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
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 };
},
}),
],
},
};
terserOptionsType: Object
Default: default
Terser minify options.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
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,
},
}),
],
},
};
extractCommentsType: 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.
BooleanEnable/disable extracting comments.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
extractComments: true,
}),
],
},
};
StringExtract all or some (use /^\**!|@preserve|@license|@cc_on/i RegExp) comments.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
extractComments: 'all',
}),
],
},
};
RegExpAll 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;
},
}),
],
},
};
ObjectAllow 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 ${licenseFile}`;
},
},
}),
],
},
};
conditionType: Boolean|String|RegExp|Function<(node, comment) -> Boolean|Object>
Condition what comments you need extract.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
extractComments: {
condition: 'some',
filename: (fileData) => {
// The "fileData" argument contains object with "filename", "basename", "query" and "hash"
return `${fileData.filename}.LICENSE.txt${fileData.query}`;
},
banner: (licenseFile) => {
return `License information can be found in ${licenseFile}`;
},
},
}),
],
},
};
filenameType: 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.
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}`;
},
},
}),
],
},
};
bannerType: 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}`;
},
},
}),
],
},
};
warningsFilterType: Function<(warning, file, source) -> Boolean>
Default: () => true
Allow to filter terser warnings.
Return true to keep the warning, a falsy value (false/null/undefined) otherwise.
⚠️ The
sourceargument will containundefinedif you don't use source maps.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
warningsFilter: (warning, file, source) => {
if (/Dropping unreachable code/i.test(warning)) {
return true;
}
if (/file\.js/i.test(file)) {
return true;
}
if (/source\.js/i.test(source)) {
return true;
}
return false;
},
}),
],
},
};
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,
}),
],
},
};
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,
}),
],
},
};
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);
},
}),
],
},
};
Please take a moment to read our contributing guidelines if you haven't yet done so.
FAQs
Terser plugin for webpack
We found that terser-webpack-plugin demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 3 open source maintainers collaborating on the project.
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