compression-webpack-plugin

Prepare compressed versions of assets to serve them with Content-Encoding.

Getting Started

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

npm install compression-webpack-plugin --save-dev

or

yarn add -D compression-webpack-plugin

or

pnpm add -D compression-webpack-plugin

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

webpack.config.js

constCompressionPlugin=require("compression-webpack-plugin");module.exports={plugins: [newCompressionPlugin()],};

Finally, run webpack using the method you normally use (e.g., via CLI or an npm script).

Options

• test
• include
• exclude
• algorithm
• compressionOptions
• threshold
• minRatio
• filename
• deleteOriginalAssets

test

Type:

typetest=string|RegExp|(string|RegExp)[];

Default: undefined

Include all assets that pass test assertion.

webpack.config.js

module.exports={plugins: [newCompressionPlugin({test: /\.js(\?.*)?$/i,}),],};

include

Type:

typeinclude=string|RegExp|(string|RegExp)[];

Default: undefined

Include all assets matching any of these conditions.

webpack.config.js

module.exports={plugins: [newCompressionPlugin({include: /\/includes/,}),],};

exclude

Type:

typeexclude=string|RegExp|(string|RegExp)[];

Default: undefined

Exclude all assets matching any of these conditions.

webpack.config.js

module.exports={plugins: [newCompressionPlugin({exclude: /\/excludes/,}),],};

algorithm

Type:

typealgorithm=|string|((input: Buffer,options: CompressionOptions,callback: (error: Error|null|undefined,result:
|string|ArrayBuffer|SharedArrayBuffer|Uint8Array|readonlynumber[]|{valueOf(): ArrayBuffer|SharedArrayBuffer;}|{valueOf(): string|Uint8Array|readonlynumber[];}|{valueOf(): string;}|{[Symbol.toPrimitive](hint: "string"): string;},)=>void,)=>void);

Defines the compression algorithm or function to use. Defaults to gzip.

Note

If you use a custom function for the algorithm option, the default value of compressionOptions will be an empty object {}.

string

The algorithm is based on the Node.js zlib module.

webpack.config.js

module.exports={plugins: [newCompressionPlugin({algorithm: "gzip",}),],};

function

Allow you to specify a custom compression function.

webpack.config.js

module.exports={plugins: [newCompressionPlugin({algorithm(input,compressionOptions,callback){returncompressionFunction(input,compressionOptions,callback);},}),],};

compressionOptions

Type:

interfacecompressionOptions{flush?: number;finishFlush?: number;chunkSize?: number;windowBits?: number;level?: number;memLevel?: number;strategy?: number;dictionary?: Buffer|TypedArray|DataView|ArrayBuffer;info?: boolean;maxOutputLength?: number;}

Default: { level: 9 }

Compression options for algorithm.

You can find all available options in the zlib documentation.

Note

If you use a custom function for the algorithm option, the default value of compressionOptions will be an empty object {}.

webpack.config.js

module.exports={plugins: [newCompressionPlugin({compressionOptions: {level: 1},}),],};

threshold

Type:

typethreshold=number;

Default: 0

Only assets larger than this size (in bytes) are processed.

webpack.config.js

module.exports={plugins: [newCompressionPlugin({threshold: 8192,}),],};

minRatio

Type:

typeminRatio=number;

Default: 0.8

Only assets that compress better than this ratio are processed (minRatio = Compressed Size / Original Size). For example, if you have a image.png file with a size of 1024 bytes, and its compressed version is of 768 bytes, the minRatio is 0.75. In other words, assets will be processed only when the ratio of Compressed Size / Original Size is less than the specified minRatio.

You can use a value of 1 to process assets that are smaller than or equal to the original size.

Use a value of Infinity to process all assets, even if they are larger than the original size or their original size is 0 bytes (useful when you are pre-zipping all assets for AWS).

Use a value of Number.MAX_SAFE_INTEGER to process all assets even if they are larger than the original size, excluding assets with their original size is 0 bytes.

webpack.config.js

module.exports={plugins: [newCompressionPlugin({// Compress all assets, including files with `0` bytes size// minRatio: Infinity// Compress all assets, excluding files with `0` bytes size// minRatio: Number.MAX_SAFE_INTEGERminRatio: 0.8,}),],};

filename

Type:

typefilename=string|((pathdata: PathData)=>string);

Default: "[path][base].gz"

The target asset filename.

string

For example, given an asset path: assets/images/image.png?foo=bar#hash:

[path] is replaced with the directories of the original asset, including the trailing / (assets/images/).

[file] is replaced with the path of the original asset (assets/images/image.png).

[base] is replaced with the base name ([name] + [ext]) of the original asset (image.png).

[name] is replaced with the name of the original asset (image).

[ext] is replaced with the extension of the original asset, including the . (.png).

[query] is replaced with the query of the original asset, including the ? (?foo=bar).

[fragment] is replaced with the fragment (in the concept of URL it is called hash) of the original asset (#hash).

webpack.config.js

module.exports={plugins: [newCompressionPlugin({filename: "[path][base].gz",}),],};

function

webpack.config.js

module.exports={plugins: [newCompressionPlugin({filename(pathData){// The `pathData` argument contains all placeholders - `path`/`name`/`ext`/etc// Available properties described above, for the `String` notationif(/\.svg$/.test(pathData.filename)){return"assets/svg/[path][base].gz";}return"assets/js/[path][base].gz";},}),],};

deleteOriginalAssets

Type:

typedeleteOriginalAssets=|boolean|"keep-source-map"|((name: string)=>boolean);

Default: false

Determines whether the original (uncompressed) assets should be deleted after compression.

• If set to true , all original assets will be deleted.

• If set to "keep-source-map", all original assets except source maps (.map files) will be deleted.

• If a function is provided, it will be called with each asset’s name and should return true to delete the asset or false to keep it.

Example:

module.exports={plugins: [newCompressionPlugin({deleteOriginalAssets: (assetName)=>// Delete all assets except images!assetName.endsWith(".png")&&!assetName.endsWith(".jpg"),}),],};

webpack.config.js

module.exports={plugins: [newCompressionPlugin({deleteOriginalAssets: true,}),],};

To exclude sourcemaps from compression:

module.exports={plugins: [newCompressionPlugin({exclude: /.map$/,deleteOriginalAssets: "keep-source-map",}),],};

Using a custom function:

module.exports={plugins: [newCompressionPlugin({exclude: /.map$/,deleteOriginalAssets: (name)=>{if(/\.js$/.test(name)){returnfalse;}returntrue;},}),],};

Examples

Using Zopfli

Prepare compressed versions of assets using the zopfli library.

Note

@gfx/zopfli requires at least Node.js version 8.

To begin, you'll need to install @gfx/zopfli:

$ npm install @gfx/zopfli --save-dev

webpack.config.js

constzopfli=require("@gfx/zopfli");module.exports={plugins: [newCompressionPlugin({compressionOptions: {numiterations: 15,},algorithm(input,compressionOptions,callback){returnzopfli.gzip(input,compressionOptions,callback);},}),],};

Using Brotli

Brotli is a compression algorithm originally developed by Google, and offers compression superior to gzip.

Node.js v10.16.0 and later includes native support for Brotli compression in its zlib module.

You can take advantage of this built-in support for Brotli in Node 10.16.0 and later by just passing in the appropriate algorithm to the CompressionPlugin:

webpack.config.js

constzlib=require("node:zlib");module.exports={plugins: [newCompressionPlugin({filename: "[path][base].br",algorithm: "brotliCompress",test: /\.(js|css|html|svg)$/,compressionOptions: {params: {[zlib.constants.BROTLI_PARAM_QUALITY]: 11,},},threshold: 10240,minRatio: 0.8,deleteOriginalAssets: false,}),],};

[!NOTE] Brotli’s BROTLI_PARAM_QUALITY option is functionally equivalent to zlib’s level option. You can find all Brotli’s options in the relevant part of the zlib module documentation.

Using Zstandard

Zstandard (zstd) is a fast lossless compression algorithm, targeting real-time compression scenarios at zlib-level and better compression ratios.

Node.js 22.15.0 and later includes native support for Zstandard compression in its zlib module.

You can take advantage of this built-in support for zstd in Node 22.15.0 and later by just passing in the appropriate algorithm to the CompressionPlugin:

webpack.config.js

constzlib=require("node:zlib");module.exports={plugins: [newCompressionPlugin({filename: "[path][base].zst",algorithm: "zstdCompress",test: /\.(js|css|html|svg)$/,compressionOptions: {params: {[zlib.constants.ZSTD_c_compressionLevel]: 10,},},threshold: 10240,minRatio: 0.8,deleteOriginalAssets: false,}),],};

You can find all Zstandard's options in the relevant part of the zlib module documentation.

Multiple compressed versions of assets for different algorithm

webpack.config.js

constzlib=require("node:zlib");module.exports={plugins: [newCompressionPlugin({filename: "[path][base].gz",algorithm: "gzip",test: /\.js$|\.css$|\.html$/,threshold: 10240,minRatio: 0.8,}),newCompressionPlugin({filename: "[path][base].br",algorithm: "brotliCompress",test: /\.(js|css|html|svg)$/,compressionOptions: {params: {[zlib.constants.BROTLI_PARAM_QUALITY]: 11,},},threshold: 10240,minRatio: 0.8,}),],};

Contributing

We welcome contributions!

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

CONTRIBUTING

License

MIT