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 to cache and works in parallel mode.
To begin, you'll need to install css-minimizer-webpack-plugin:
$ npm install css-minimizer-webpack-plugin --save-devThen 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: {
loaders: [
{
test: /.s?css$/,
use: [MiniCssExtractPlugin.loader, 'css-loader', 'sass-loader'],
},
],
},
optimization: {
minimize: true,
minimizer: [
// For webpack@5 you can use the `...` syntax to extend existing minimizers (i.e. `terser-webpack-plugin`), uncomment the next line
// `...`
new CssMinimizerPlugin(),
],
},
};This will enable CSS optimization only in production mode.
If you want to run it also in development set the optimization.minimize option to true.
And run webpack via your preferred method.
Works only with source-map, inline-source-map, hidden-source-map and nosources-source-map values for the devtool option.
Why?
evalwraps modules ineval("string")and the minimizer does not handle strings.cheaphas not column information and minimizer generate only a single line, which leave only a single mapping.
Using supported devtool values enable source map generation.
If you use your own minify function please read the minify section for handling source maps correctly.
Type: String|RegExp|Array<String|RegExp> - default: /\.css(\?.*)?$/i
Test to match files against.
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
test: /\.foo\.css$/i,
}),
],
},
};Type: String|RegExp|Array<String|RegExp>
Default: undefined
Files to include.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
include: /\/includes/,
}),
],
},
};Type: String|RegExp|Array<String|RegExp>
Default: undefined
Files to exclude.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
exclude: /\/excludes/,
}),
],
},
};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.
Enable/disable multi-process parallel running.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
parallel: true,
}),
],
},
};Enable multi-process parallel running and set number of concurrent runs.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
parallel: 4,
}),
],
},
};Type: Function
Default: undefined
Allows you to override default minify function. By default plugin uses cssnano package. Useful for using and testing unpublished versions or forks.
⚠️ Always userequireinsideminifyfunction whenparalleloption enabled.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
sourceMap: true,
minify: (data, inputMap, minimizerOptions) => {
const postcss = require('postcss');
const plugin = postcss.plugin(
'custom-plugin',
() => (css, result) => {
// custom code
}
);
const [[filename, input]] = Object.entries(data);
const postcssOptions = {
from: filename,
to: filename,
map: {
prev: inputMap,
},
};
return postcss([plugin])
.process(input, postcssOptions)
.then((result) => {
return {
css: result.css,
map: result.map,
warnings: result.warnings(),
};
});
},
}),
],
},
};Type: Object
Default: { preset: 'default' }
Cssnano optimisations options.
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: {
preset: [
'default',
{
discardComments: { removeAll: true },
},
],
},
}),
],
},
};Type: Function<(warning, file, source) -> Boolean>
Default: () => true
Allow to filter css-minimizer warnings (By default cssnano).
Return true to keep the warning, a falsy value (false/null/undefined) otherwise.
⚠️ Thesourceargument will containundefinedif 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;
},
}),
],
},
};Don't forget to enable sourceMap options for all loaders.
const CssMinimizerPlugin = require('css-minimizer-webpack-plugin');
module.exports = {
module: {
loaders: [
{
test: /.s?css$/,
use: [
MiniCssExtractPlugin.loader,
{ loader: 'css-loader', options: { sourceMap: true } },
{ loader: 'sass-loader', options: { sourceMap: true } },
],
},
],
},
optimization: {
minimizer: [
new CssMinimizerPlugin({
sourceMap: true,
}),
],
},
};Remove all comments (including comments starting with /*!).
module.exports = {
optimization: {
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: {
preset: [
'default',
{
discardComments: { removeAll: true },
},
],
},
}),
],
},
};Using custom minifier csso
By default plugin uses cssnano package. It is possible to use another minify function.
⚠️ Always userequireinsideminifyfunction whenparalleloption enabled.
webpack.config.js
module.exports = {
devtool: 'source-map',
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
sourceMap: true,
minify: async (data, inputMap) => {
const csso = require('csso');
const sourcemap = require('source-map');
const [[filename, input]] = Object.entries(data);
const minifiedCss = csso.minify(input, {
filename: filename,
sourceMap: true,
});
if (inputMap) {
minifiedCss.map.applySourceMap(
new sourcemap.SourceMapConsumer(inputMap),
filename
);
}
return {
css: minifiedCss.css,
map: minifiedCss.map.toJSON(),
};
},
}),
],
},
};Using custom minifier clean-css
By default plugin uses cssnano package. It is possible to use another minify function.
⚠️ Always userequireinsideminifyfunction whenparalleloption enabled.
webpack.config.js
module.exports = {
devtool: 'source-map',
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
sourceMap: true,
minify: async (data, inputMap) => {
// eslint-disable-next-line global-require
const CleanCSS = require('clean-css');
const [[filename, input]] = Object.entries(data);
const minifiedCss = await new CleanCSS({ sourceMap: true }).minify({
[filename]: {
styles: input,
sourceMap: inputMap,
},
});
return {
css: minifiedCss.styles,
map: minifiedCss.sourceMap.toJSON(),
warnings: minifiedCss.warnings,
};
},
}),
],
},
};Please take a moment to read our contributing guidelines if you haven't yet done so.