webpack
css-minimizer-webpack-plugin
This plugin uses cssnano to optimize and minify your CSS.
It serves as a more accurate alternative to optimize-css-assets-webpack-plugin, with better support for source maps, assets with query strings, caching, and parallel processing.
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 CssMinimizerPlugin = require("css-minimizer-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
module.exports = {
module: {
rules: [
{
test: /\.s?css$/,
use: [MiniCssExtractPlugin.loader, "css-loader", "sass-loader"],
},
],
},
optimization: {
minimizer: [
// For webpack v5, you can use the `...` syntax to extend existing minimizers (i.e. `terser-webpack-plugin`), uncomment the next line // `...`,
new CssMinimizerPlugin(),
],
},
plugins: [new MiniCssExtractPlugin()],
};[!NOTE]
This enables CSS optimization only in production mode by default.
To enable it in development mode as well, set the optimization.minimize option to true:
webpack.config.js
// [...]
module.exports = {
optimization: {
// [...]
minimize: true,
},
};Finally, run Webpack using your preferred method.
Note about source maps
This plugin works only with source-map, inline-source-map, hidden-source-map and nosources-source-map values for the devtool option.
Why? Because CSS support only these source map types.
The plugin respects the devtool setting and uses the SourceMapDevToolPlugin internally.
Using a supported devtool value enables source map generation.
Enabling the columns option in SourceMapDevToolPlugin also allows source map generation.
Use source maps to map error message locations to their original modules (note that this may slow down compilation).
If you use your own minify function please refer to the minify section for correct handling of source maps.
Options
| Name | Type | Default | Description | |||
|---|---|---|---|---|---|---|
test |
`String\ | RegExp\ | Array<String\ | RegExp>` | /\.css(\?.*)?$/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 or 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 |
Allows filtering of 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.
The default number of concurrent runs: os.cpus().length - 1 or os.availableParallelism() - 1 (if this function is supported).
ℹ️ 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 or 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 specify the 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
Overrides the default minify function.
By default, plugin uses cssnano package.
This is useful when using or 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
requireinsideminifyfunction whenparalleloption is 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) =>
// Custom minifier function
({
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 parallelization is enabled, the packages in
minimizerOptionsmust be referenced 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 (⚠ 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 any of these options are passed as a function, the
paralleloption 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
Filter css-minimizer warnings (By default cssnano).
Return true to keep the warning, or a falsy value (false/null/undefined) to suppress it.
[!WARNING]
The
sourceparameter will beundefinedunless source maps are enabled.
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 those 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 = {
// devtool: "source-map", // Uncomment for source maps
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 = {
// devtool: "source-map", // Uncomment for source maps
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minify: CssMinimizerPlugin.swcMinify,
// Uncomment this line for options
// minimizerOptions: {},
}),
],
},
};Contributing
We welcome all contributions!
If you're new here, please take a moment to review our contributing guidelines.