CasperSecurity
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# terser-webpack-plugin
This plugin uses [terser](https://github.com/terser/terser) to minify/minimize your JavaScript.
## Getting Started
Webpack v5 comes with the latest `terser-webpack-plugin` out of the box. If you are using Webpack v5 or above and wish to customize the options, you will still need to install `terser-webpack-plugin`. Using Webpack v4, you have to install `terser-webpack-plugin` v4.
To begin, you'll need to install `terser-webpack-plugin`:
```console
$ npm install terser-webpack-plugin --save-dev
```
Then add the plugin to your `webpack` config. For example:
**webpack.config.js**
```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`](https://webpack.js.org/configuration/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.
Using supported `devtool` values enable source map generation.
## Options
| Name | Type | Default | Description |
| :---------------------------------------: | :-----------------------------------------------------------------------------: | :----------------------------------------------------------: | :------------------------------------------------------------------------ |
| **[`test`](#test)** | `String\|RegExp\|Array<String\|RegExp>` | `/\.m?js(\?.*)?$/i` | Test to match files against. |
| **[`include`](#include)** | `String\|RegExp\|Array<String\|RegExp>` | `undefined` | Files to include. |
| **[`exclude`](#exclude)** | `String\|RegExp\|Array<String\|RegExp>` | `undefined` | Files to exclude. |
| **[`parallel`](#parallel)** | `Boolean\|Number` | `true` | Use multi-process parallel running to improve the build speed. |
| **[`minify`](#minify)** | `Function` | `TerserPlugin.terserMinify` | Allows you to override default minify function. |
| **[`terserOptions`](#terseroptions)** | `Object` | [`default`](https://github.com/terser/terser#minify-options) | Terser [minify options](https://github.com/terser/terser#minify-options). |
| **[`extractComments`](#extractcomments)** | `Boolean\|String\|RegExp\|Function<(node, comment) -> Boolean\|Object>\|Object` | `true` | Whether comments shall be extracted to a separate file. |
### `test`
Type: `String|RegExp|Array<String|RegExp>`
Default: `/\.m?js(\?.*)?$/i`
Test to match files against.
**webpack.config.js**
```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**
```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**
```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 avoid `Error: Call retries were exceeded` (see [#143](https://github.com/webpack-contrib/terser-webpack-plugin/issues/143), [#202](https://github.com/webpack-contrib/terser-webpack-plugin/issues/202)).
#### `Boolean`
Enable/disable multi-process parallel running.
**webpack.config.js**
```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**
```js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
parallel: 4,
}),
],
},
};
```
### `minify`
Type: `Function`
Default: `TerserPlugin.terserMinify`
Allows you to override default minify function.
By default plugin uses [terser](https://github.com/terser/terser) package.
Useful for using and testing unpublished versions or forks.
> ⚠️ **Always use `require` inside `minify` function when `parallel` option enabled**.
**webpack.config.js**
```js
// Can be async
const minify = (input, sourceMap, minimizerOptions, extractsComments) => {
// The `minimizerOptions` option contains option from the `terserOptions` option
// You can use `minimizerOptions.myCustomOption`
// Custom logic for extract comments
const { map, code } = require("uglify-module") // Or require('./path/to/uglify-module')
.minify(input, {
/* Your options for minification */
});
return { map, code, warnings: [], errors: [], extractedComments: [] };
};
// Used to regenerate `fullhash`/`chunkhash` between different implementation
// Example: you fix a bug in custom minimizer/custom function, but unfortunately webpack doesn't know about it, so you will get the same fullhash/chunkhash
// to avoid this you can provide version of your custom minimizer
// You don't need if you use only `contenthash`
minify.getMinimizerVersion = () => {
let packageJson;
try {
// eslint-disable-next-line global-require, import/no-extraneous-dependencies
packageJson = require("uglify-module/package.json");
} catch (error) {
// Ignore
}
return packageJson && packageJson.version;
};
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
terserOptions: {
myCustomOption: true,
},
minify,
}),
],
},
};
```
### `terserOptions`
Type: `Object`
Default: [default](https://github.com/terser/terser#minify-options)
Terser [options](https://github.com/terser/terser#minify-options).
**webpack.config.js**
```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](https://github.com/webpack/webpack/commit/71933e979e51c533b432658d5e37917f9e71595a)).
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**
```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**
```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**
```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**
```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**
```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 ${licenseFile}`;
},
},
}),
],
},
};
```
##### `condition`
Type: `Boolean|String|RegExp|Function<(node, comment) -> Boolean|Object>`
Condition what comments you need extract.
**webpack.config.js**
```js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
extractComments: {
condition: "some",
filename: (fileData) => {
// The "fileData" argument contains object with "filename", "basename", "query" and "hash"
return `${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**
```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 ${commentsFile} */`
The banner text that points to the extracted file and will be added on top of the original file.
Can be `false` (no banner), a `String`, or a `Function<(string) -> String>` that will be called with the filename where extracted comments have been stored.
Will be wrapped into comment.
**webpack.config.js**
```js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
extractComments: {
condition: true,
filename: (fileData) => {
// The "fileData" argument contains object with "filename", "basename", "query" and "hash"
return `${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**
```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**
```js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
terserOptions: {
format: {
comments: false,
},
},
extractComments: false,
}),
],
},
};
```
### [`uglify-js`](https://github.com/mishoo/UglifyJS)
[`UglifyJS`](https://github.com/mishoo/UglifyJS) is a JavaScript parser, minifier, compressor and beautifier toolkit.
**webpack.config.js**
```js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
minify: TerserPlugin.uglifyJsMinify,
// `terserOptions` options will be passed to `uglify-js`
// Link to options - https://github.com/mishoo/UglifyJS#minify-options
terserOptions: {},
}),
],
},
};
```
### [`swc`](https://github.com/swc-project/swc)
[`swc`](https://github.com/swc-project/swc) is a super-fast compiler written in rust; producing widely-supported javascript from modern standards and typescript.
> ⚠ the `extractComments` option is not supported and all comments will be removed by default, it will be fixed in future
**webpack.config.js**
```js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
minify: TerserPlugin.swcMinify,
// `terserOptions` options will be passed to `swc` (`@swc/core`)
// Link to options - https://swc.rs/docs/config-js-minify
terserOptions: {},
}),
],
},
};
```
### [`esbuild`](https://github.com/evanw/esbuild)
[`esbuild`](https://github.com/evanw/esbuild) is an extremely fast JavaScript bundler and minifier.
> ⚠ the `extractComments` option is not supported and all legal comments (i.e. copyright, licenses and etc) will be preserved
**webpack.config.js**
```js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
minify: TerserPlugin.esbuildMinify,
// `terserOptions` options will be passed to `esbuild`
// Link to options - https://esbuild.github.io/api/#minify
// Note: the `minify` options is true by default (and override other `minify*` options), so if you want to disable the `minifyIdentifiers` option (or other `minify*` options) please use:
// terserOptions: {
// minify: false,
// minifyWhitespace: true,
// minifyIdentifiers: false,
// minifySyntax: true,
// },
terserOptions: {},
}),
],
},
};
```
### Custom Minify Function
Override default minify function - use `uglify-js` for minification.
**webpack.config.js**
```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);
},
}),
],
},
};
```
### Typescript
With default terser minify function:
```ts
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin({
terserOptions: {
compress: true,
},
}),
],
},
};
```
With built-in minify functions:
```ts
import type { JsMinifyOptions as SwcOptions } from "@swc/core";
import type { MinifyOptions as UglifyJSOptions } from "uglify-js";
import type { TransformOptions as EsbuildOptions } from "esbuild";
import type { MinifyOptions as TerserOptions } from "terser";
module.exports = {
optimization: {
minimize: true,
minimizer: [
new TerserPlugin<SwcOptions>({
minify: TerserPlugin.swcMinify,
terserOptions: {
// `swc` options
},
}),
new TerserPlugin<UglifyJSOptions>({
minify: TerserPlugin.uglifyJsMinify,
terserOptions: {
// `uglif-js` options
},
}),
new TerserPlugin<EsbuildOptions>({
minify: TerserPlugin.esbuildMinify,
terserOptions: {
// `esbuild` options
},
}),
// Alternative usage:
new TerserPlugin<TerserOptions>({
minify: TerserPlugin.terserMinify,
terserOptions: {
// `terser` options
},
}),
],
},
};
```
## Contributing
Please take a moment to read our contributing guidelines if you haven't yet done so.
[CONTRIBUTING](./.github/CONTRIBUTING.md)
## License
[MIT](./LICENSE)
[npm]: https://img.shields.io/npm/v/terser-webpack-plugin.svg
[npm-url]: https://npmjs.com/package/terser-webpack-plugin
[node]: https://img.shields.io/node/v/terser-webpack-plugin.svg
[node-url]: https://nodejs.org
[deps]: https://david-dm.org/webpack-contrib/terser-webpack-plugin.svg
[deps-url]: https://david-dm.org/webpack-contrib/terser-webpack-plugin
[tests]: https://github.com/webpack-contrib/terser-webpack-plugin/workflows/terser-webpack-plugin/badge.svg
[tests-url]: https://github.com/webpack-contrib/terser-webpack-plugin/actions
[cover]: https://codecov.io/gh/webpack-contrib/terser-webpack-plugin/branch/master/graph/badge.svg
[cover-url]: https://codecov.io/gh/webpack-contrib/terser-webpack-plugin
[chat]: https://img.shields.io/badge/gitter-webpack%2Fwebpack-brightgreen.svg
[chat-url]: https://gitter.im/webpack/webpack
[size]: https://packagephobia.now.sh/badge?p=terser-webpack-plugin
[size-url]: https://packagephobia.now.sh/result?p=terser-webpack-plugin