compression-webpack-plugin

What is compression-webpack-plugin?

The compression-webpack-plugin is a plugin for Webpack that allows you to compress assets with various compression algorithms before they are output to the file system. This can help reduce the size of your assets, leading to faster load times for your web application.

What are compression-webpack-plugin's main functionalities?

Compression of assets

This feature allows you to compress files using gzip. The 'test' option is a RegExp that matches the files to compress.

const CompressionPlugin = require('compression-webpack-plugin');

module.exports = {
  plugins: [
    new CompressionPlugin({
      algorithm: 'gzip',
      test: /\.js(\?.*)?$/i,
    }),
  ],
};

Custom compression options

This feature allows you to use different compression algorithms like Brotli, and set custom compression options such as the compression level.

const CompressionPlugin = require('compression-webpack-plugin');

module.exports = {
  plugins: [
    new CompressionPlugin({
      algorithm: 'brotliCompress',
      test: /\.js(\?.*)?$/i,
      compressionOptions: { level: 11 },
    }),
  ],
};

Asset filtering

This feature allows you to exclude certain assets from being compressed by using the 'exclude' option.

const CompressionPlugin = require('compression-webpack-plugin');

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

Threshold and minRatio settings

This feature allows you to only compress assets that are larger than a certain size (threshold) and only if the compression ratio is below a certain value (minRatio).

const CompressionPlugin = require('compression-webpack-plugin');

module.exports = {
  plugins: [
    new CompressionPlugin({
      test: /\.js(\?.*)?$/i,
      threshold: 10240,
      minRatio: 0.8
    }),
  ],
};

Other packages similar to compression-webpack-plugin

brotli-webpack-plugin

This package is similar to compression-webpack-plugin but is specifically focused on using the Brotli compression algorithm. It may offer more advanced Brotli-specific options.

zopfli-webpack-plugin

Similar to compression-webpack-plugin, this plugin uses the Zopfli algorithm for compression, which can result in smaller file sizes but may take longer to compress.

uglifyjs-webpack-plugin

While not a direct alternative, uglifyjs-webpack-plugin can reduce the size of JavaScript files by minifying them, which is a different approach to optimization compared to compression.

README

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

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

webpack.config.js

const CompressionPlugin = require("compression-webpack-plugin");

module.exports = {
  plugins: [new CompressionPlugin()],
};

And run webpack via your preferred method.

Options

Name	Type	Default	Description
test	{String|RegExp|Array<String|RegExp>}	undefined	Include all assets that pass test assertion
include	{String|RegExp|Array<String|RegExp>}	undefined	Include all assets matching any of these conditions
exclude	{String|RegExp|Array<String|RegExp>}	undefined	Exclude all assets matching any of these conditions
algorithm	{String|Function}	gzip	The compression algorithm/function
compressionOptions	{Object}	maximum available compression level, for gzip: { level: 9 }	Compression options for algorithm
threshold	{Number}	0	Only assets bigger than this size are processed (in bytes)
minRatio	{Number}	0.8	Only assets that compress better than this ratio are processed (minRatio = Compressed Size / Original Size)
filename	{String|Function}	[path][base].gz	The target asset filename
deleteOriginalAssets	{Boolean|'keep-source-map'}	false	Whether to delete the original assets or not
cache	{Boolean}	true	Enable file caching

test

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

Include all assets that pass test assertion.

webpack.config.js

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

include

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

Include all assets matching any of these conditions.

webpack.config.js

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

exclude

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

Exclude all assets matching any of these conditions.

webpack.config.js

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

algorithm

Type: String|Function Default: gzip

The compression algorithm/function.

ℹ️ If you use custom function for the algorithm option, the default value of the compressionOptions option is {}.

String

The algorithm is taken from zlib.

webpack.config.js

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

Function

Allow to specify a custom compression function.

webpack.config.js

module.exports = {
  plugins: [
    new CompressionPlugin({
      algorithm(input, compressionOptions, callback) {
        return compressionFunction(input, compressionOptions, callback);
      },
    }),
  ],
};

compressionOptions

Type: Object Default: { level: 9 }

Compression options for algorithm.

You can find all options here zlib.

ℹ️ If you use custom function for the algorithm option, the default value is {}.

webpack.config.js

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

threshold

Type: Number Default: 0

Only assets bigger than this size are processed. In bytes.

webpack.config.js

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

minRatio

Type: Number Default: 0.8

Only assets that compress better than this ratio are processed (minRatio = Compressed Size / Original Size). Example: you have image.png file with 1024b size, compressed version of file has 768b size, so minRatio equal 0.75. In other words assets will be processed when the Compressed Size / Original Size value less minRatio value.

You can use 1 value to process assets that are smaller than the original.

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: [
    new CompressionPlugin({
      // Compress all assets, including files with `0` bytes size
      // minRatio: Infinity

      // Compress all assets, excluding files with `0` bytes size
      // minRatio: Number.MAX_SAFE_INTEGER

      minRatio: 0.8,
    }),
  ],
};

filename

Type: String|Function Default: "[path][base].gz"

The target asset filename.

String

For example we have assets/images/image.png?foo=bar#hash:

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

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

[base] is replaced with the base ([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, included . (.png).

[query] is replaced with the query of the original asset, included ? (?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: [
    new CompressionPlugin({
      filename: "[path][base].gz",
    }),
  ],
};

Function

webpack.config.js

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

        return "assets/js/[path][base].gz";
      },
    }),
  ],
};

deleteOriginalAssets

Type: Boolean | 'keep-source-map' Default: false

Whether to delete the original assets or not.

webpack.config.js

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

To exclude sourcemaps from compression

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

cache

⚠ Ignored in webpack 5! Please use https://webpack.js.org/configuration/other-options/#cache.

Type: Boolean|String Default: true

Enable file caching. The default path to cache directory: node_modules/.cache/compression-webpack-plugin.

Boolean

Enable/disable file caching.

webpack.config.js

module.exports = {
  plugins: [
    new CompressionPlugin({
      cache: true,
    }),
  ],
};

String

Enable file caching and set path to cache directory.

webpack.config.js

module.exports = {
  plugins: [
    new CompressionPlugin({
      cache: "path/to/cache",
    }),
  ],
};

Examples

Using Zopfli

Prepare compressed versions of assets using zopfli library.

ℹ️ @gfx/zopfli require minimum 8 version of node.

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

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

webpack.config.js

const zopfli = require("@gfx/zopfli");

module.exports = {
  plugins: [
    new CompressionPlugin({
      compressionOptions: {
        numiterations: 15,
      },
      algorithm(input, compressionOptions, callback) {
        return zopfli.gzip(input, compressionOptions, callback);
      },
    }),
  ],
};

Using Brotli

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

Node 10.16.0 and later has native support for Brotli compression in its zlib module.

We 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

const zlib = require("zlib");

module.exports = {
  plugins: [
    new CompressionPlugin({
      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.

Multiple compressed versions of assets for different algorithm

webpack.config.js

const zlib = require("zlib");

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

Contributing

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

CONTRIBUTING

License

MIT