CssMinimizerWebpackPlugin
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.
Getting Started
To begin, you'll need to install css-minimizer-webpack-plugin:
$ npm install css-minimizer-webpack-plugin --save-dev
Then add the plugin to your webpack configuration. For example:
webpack.config.js
const CssMinimizerPlugin = require('css-minimizer-webpack-plugin');
module.exports = {
module: {
loaders: [
{
test: /.s?css$/,
use: [MiniCssExtractPlugin.loader, 'css-loader', 'sass-loader'],
},
],
},
optimization: {
minimize: true,
minimizer: [new CssMinimizerPlugin()],
},
};This will enable CSS optimization only in production mode.
If you want to run it also in development, put the plugin configuration in the plugins option array.
And run webpack via your preferred method.
Options
test
Type: String|RegExp|Array<String|RegExp> - default: /\.css(\?.*)?$/i
Test to match files against.
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
test: /\.foo\.css$/i,
}),
],
},
};include
Type: String|RegExp|Array<String|RegExp>
Default: undefined
Files to include.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
include: /\/includes/,
}),
],
},
};exclude
Type: String|RegExp|Array<String|RegExp>
Default: undefined
Files to exclude.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
exclude: /\/excludes/,
}),
],
},
};cache
⚠ Ignored in webpack 5! Please use https://webpack.js.org/configuration/other-options/#cache.
Type: Boolean|String
Default: true
Enable file caching.
Default path to cache directory: node_modules/.cache/css-minimizer-webpack-plugin.
ℹ️ If you use your own
minifyfunction please read theminifysection for cache invalidation correctly.
Boolean
Enable/disable file caching.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
cache: true,
}),
],
},
};String
Enable file caching and set path to cache directory.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
cache: 'path/to/cache',
}),
],
},
};cacheKeys
⚠ Ignored in webpack 5! Please use https://webpack.js.org/configuration/other-options/#cache.
Type: Function<(defaultCacheKeys, file) -> Object>
Default: defaultCacheKeys => defaultCacheKeys
Allows you to override default cache keys.
Default cache keys:
({
cssMinimizer: require('cssnano/package.json').version, // cssnano version
'css-minimizer-webpack-plugin': require('../package.json').version, // plugin version
'css-minimizer-webpack-plugin-options': this.options, // plugin options
path: compiler.outputPath ? `${compiler.outputPath}/${file}` : file, // asset path
hash: crypto.createHash('md4').update(input).digest('hex'), // source file hash
});webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
cache: true,
cacheKeys: (defaultCacheKeys, file) => {
defaultCacheKeys.myCacheKey = 'myCacheKeyValue';
return defaultCacheKeys;
},
}),
],
},
};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.
ℹ️ Parallelization can speedup your build significantly and is therefore highly recommended.
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,
}),
],
},
};sourceMap
Type: Boolean|Object
Default: false (see below for details around devtool value and SourceMapDevToolPlugin plugin)
Enable (and configure) source map support. Use PostCss SourceMap options.
Default configuration when enabled: { inline: false }.
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.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
sourceMap: true,
}),
],
},
};minify
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 use
requireinsideminifyfunction whenparalleloption enabled.
webpack.config.js
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minify: (data) => {
const postcss = require('postcss');
const { input, postcssOptions, minimizerOptions } = data;
const plugin = postcss.plugin(
'custom-plugin',
() => (css, result) => {
// custom code
}
);
return postcss([plugin])
.process(input, postcssOptions)
.then((result) => {
return {
css: result.css,
map: result.map,
error: result.error,
warnings: result.warnings(),
};
});
},
}),
],
},
};minimizerOptions
Type: Object
Default: { preset: 'default' }
Cssnano optimisations options.
module.exports = {
optimization: {
minimize: true,
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: {
preset: [
'default',
{
discardComments: { removeAll: true },
},
],
},
}),
],
},
};warningsFilter
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.
⚠️ The
sourceargument 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;
},
}),
],
},
};Examples
Use sourcemaps
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
Remove all comments (including comments starting with /*!).
module.exports = {
optimization: {
minimizer: [
new CssMinimizerPlugin({
minimizerOptions: {
preset: [
'default',
{
discardComments: { removeAll: true },
},
],
},
}),
],
},
};Contributing
Please take a moment to read our contributing guidelines if you haven't yet done so.