JarCasting
terser-webpack-plugin
This plugin uses terser to minify your JavaScript.
Getting Started
If you are using webpack v5 or above you do not need to install this plugin. Webpack v5 comes with the latest terser-webpack-plugin out of the box. Using Webpack v4, you have to install terser-webpack-plugin v4.
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.
Note about source maps
Works only with source-map, inline-source-map, hidden-source-map and nosources-source-map values for the devtool option.
Why?
evalwraps modules ineval("string")and the minimizer does not handle strings.cheaphas not column information and minimizer generate only a single line, which leave only a single mapping.
Using supported devtool values enable source map generation.
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/,
}),
],
},
};
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 avoidError: 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,
}),
],
},
};
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 userequireinsideminifyfunction whenparalleloption 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,
// Deprecated
output: null,
format: 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.format.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 thetxtextension. Usingjs/cjs/mjsextensions 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: {
format: {
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: {
format: {
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({
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.
