css-minimizer-webpack-plugin
This plugin uses cssnano to optimize and minify your CSS.
Just like optimize-css-assets-webpack-plugin but more accurate with source maps and assets using query string, allows caching and works in parallel mode.
Getting Started
To begin, you'll need to install css-minimizer-webpack-plugin:
npm install css-minimizer-webpack-plugin --save-devor
yarn add -D css-minimizer-webpack-pluginor
pnpm add -D css-minimizer-webpack-pluginThen add the plugin to your webpack configuration. For example:
webpack.config.js
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const CssMinimizerPlugin = require("css-minimizer-webpack-plugin");
module.exports = {
module: {
rules: [
{
test: /.s?css$/,
use: [MiniCssExtractPlugin.loader, "css-loader", "sass-loader"],
},
],
},
optimization: {
minimizer: [
// For webpack@5 you can use the `...` syntax to extend existing minimizers (i.e. `terser-webpack-plugin`), uncomment the next line
// `...`,
new CssMinimizerPlugin(),
],
},
plugins: [new MiniCssExtractPlugin()],
};This will enable CSS optimization only in production mode.
If you want to run it also in development set the optimization.minimize option to true:
webpack.config.js
// [...]
module.exports = {
optimization: {
// [...]
minimize: true,
},
};And run webpack via your preferred method.
Note about source maps
Works only with source-map, inline-source-map, hidden-source-map and nosources-source-map values for the devtool option.
Why? Because CSS support only these source map types.
The plugin respect the devtool and using the SourceMapDevToolPlugin plugin.
Using supported devtool values enable source map generation.
Using SourceMapDevToolPlugin with enabled the columns option enables source map generation.
Use source maps to map error message locations to modules (this slows down the compilation).
If you use your own minify function please read the minify section for handling source maps correctly.
Options
| Name | Type | Default | Description |
|---|---|---|---|
test |
String|RegExp|Array<String|RegExp> |
/\.css(\?.*)?$/i |
Test to match files against. |
include |
String|RegExp|Array<String|RegExp> |
undefined |
Files to include. |
exclude |
String|RegExp|Array<String|RegExp> |
undefined |
Files to exclude. |
parallel |
Boolean|Number |
true |
Enable/disable multi-process parallel running. |
minify |
Function|Array<Function> |
CssMinimizerPlugin.cssnanoMinify |
Allows to override default minify function. |
minimizerOptions |
Object|Array<Object> |
{ preset: 'default' } |
Cssnano optimisations options. |
warningsFilter |
Function<(warning, file, source) -> Boolean> |
() => true |
Allow to filter css-minimizer warnings. |
test
Type: String|RegExp|Array<String|RegExp> - default: /\.css(\?.*)?$/i
Test to match files against.
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
test: /\.foo\.css$/i,
}),
],
},
};include
Type: String|RegExp|Array<String|RegExp>
Default: undefined
Files to include.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
include: /\/includes/,
}),
],
},
};exclude
Type: String|RegExp|Array<String|RegExp>
Default: undefined
Files to exclude.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
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.
βΉοΈ Parallelization can speed up your build significantly and is therefore highly recommended. If a parallelization is enabled, the packages in
minimizerOptionsmust be required via strings (packageNameorrequire.resolve(packageName)). Read more inminimizerOptions
Boolean
Enable/disable multi-process parallel running.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
parallel: true,
}),
],
},
};Number
Enable multi-process parallel running and set number of concurrent runs.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
parallel: 4,
}),
],
},
};minify
Type: Function|Array<Function>
Default: CssMinimizerPlugin.cssnanoMinify
Allows overriding default minify function. By default, plugin uses cssnano package. Useful for using and testing unpublished versions or forks.
Possible options:
CssMinimizerPlugin.cssnanoMinifyCssMinimizerPlugin.cssoMinifyCssMinimizerPlugin.cleanCssMinifyCssMinimizerPlugin.esbuildMinifyCssMinimizerPlugin.lightningCssMinify(previouslyCssMinimizerPlugin.parcelCssMinify, the package was renamed, but we keep it for backward compatibility)async (data, inputMap, minimizerOptions) => {return {code: "a{color: red}", map: "...", warnings: [], errors: []}}
Warning
Always use require inside minify function when parallel option enabled.
Function
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: {
level: {
1: {
roundingPrecision: "all=3,px=5",
},
},
},
minify: CssMinimizerPlugin.cleanCssMinify,
}),
],
},
};Array
If an array of functions is passed to the minify option, the minimizerOptions must also be an array.
The function index in the minify array corresponds to the options object with the same index in the minimizerOptions array.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: [
{}, // Options for the first function (CssMinimizerPlugin.cssnanoMinify)
{}, // Options for the second function (CssMinimizerPlugin.cleanCssMinify)
{}, // Options for the third function
],
minify: [
CssMinimizerPlugin.cssnanoMinify,
CssMinimizerPlugin.cleanCssMinify,
async (data, inputMap, minimizerOptions) => {
// To do something
return {
code: `a{color: red}`,
map: `{"version": "3", ...}`,
warnings: [],
errors: [],
};
},
],
}),
],
},
};minimizerOptions
Type: Object|Array<Object>
Default: { preset: 'default' }
Cssnano optimisations options.
Object
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: {
preset: [
"default",
{
discardComments: { removeAll: true },
},
],
},
}),
],
},
};Array
The function index in the minify array corresponds to the options object with the same index in the minimizerOptions array.
If you use minimizerOptions like object, all minify function accept it.
If a parallelization is enabled, the packages in
minimizerOptionsmust be required via strings (packageNameorrequire.resolve(packageName)). In this case, we shouldn't userequire/import.
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: {
preset: require.resolve("cssnano-preset-simple"),
},
}),
],
},
};processorOptions (β only cssnano)
Type: Object
Default: { from: assetName }
Allows filtering options processoptions for the cssnano.
The parser, stringifier and syntax can be either a function or a string indicating the module that will be imported.
Warning
If a function is passed, the parallel option must be disabled..
import sugarss from "sugarss";
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
parallel: false,
minimizerOptions: {
processorOptions: {
parser: sugarss,
},
},
}),
],
},
};module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: {
processorOptions: {
parser: "sugarss",
},
},
}),
],
},
};warningsFilter
Type: Function<(warning, file, source) -> Boolean>
Default: () => true
Allow filtering css-minimizer warnings (By default cssnano).
Return true to keep the warning, a falsy value (false/null/undefined) otherwise.
Warning
The source argument will contain undefined if you don't use source maps.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
warningsFilter: (warning, file, source) => {
if (/Dropping unreachable code/i.test(warning)) {
return true;
}
if (/file\.css/i.test(file)) {
return true;
}
if (/source\.css/i.test(source)) {
return true;
}
return false;
},
}),
],
},
};Examples
Use sourcemaps
Don't forget to enable sourceMap options for all loaders.
const CssMinimizerPlugin = require("css-minimizer-webpack-plugin");
module.exports = {
devtool: "source-map",
module: {
rules: [
{
test: /.s?css$/,
use: [
MiniCssExtractPlugin.loader,
{ loader: "css-loader", options: { sourceMap: true } },
{ loader: "sass-loader", options: { sourceMap: true } },
],
},
],
},
optimization: {
minimizer: [new CssMinimizerPlugin()],
},
plugins: [new MiniCssExtractPlugin()],
};Remove all comments
Remove all comments (including comments starting with /*!).
module.exports = {
optimization: {
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: {
preset: [
"default",
{
discardComments: { removeAll: true },
},
],
},
}),
],
},
};Using custom minifier csso
webpack.config.js
module.exports = {
// Uncomment if you need source maps
// devtool: "source-map",
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minify: CssMinimizerPlugin.cssoMinify,
// Uncomment this line for options
// minimizerOptions: { restructure: false },
}),
],
},
};Using custom minifier clean-css
webpack.config.js
module.exports = {
// Uncomment if you need source maps
// devtool: "source-map",
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minify: CssMinimizerPlugin.cleanCssMinify,
// Uncomment this line for options
// minimizerOptions: { compatibility: 'ie11,-properties.merging' },
}),
],
},
};Using custom minifier esbuild
webpack.config.js
module.exports = {
// Uncomment if you need source maps
// devtool: "source-map",
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minify: CssMinimizerPlugin.esbuildMinify,
}),
],
},
};Using custom minifier lightningcss, previously @parcel/css
webpack.config.js
module.exports = {
// Uncomment if you need source maps
// devtool: "source-map",
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minify: CssMinimizerPlugin.lightningCssMinify,
// Uncomment this line for options
// minimizerOptions: { targets: { ie: 11 }, drafts: { nesting: true } },
}),
],
},
};Using custom minifier swc
webpack.config.js
module.exports = {
// Uncomment if you need source maps
// devtool: "source-map",
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minify: CssMinimizerPlugin.swcMinify,
// Uncomment this line for options
// minimizerOptions: {},
}),
],
},
};Contributing
Please take a moment to read our contributing guidelines if you haven't yet done so.