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    @stylable/webpack-plugin (for webpack ^5.30.0) is the main build utility for Stylable. It supports both development and production modes, providing various configurations that can be tweaked according to your specific needs. It enables loading Stylable files (.st.css) from local projects or imported from a 3rd party source (for example, NPM node modules).

    Getting started

    Install @stylable/webpack-plugin as a dev dependency in your local project.

    Install using npm:

    npm install @stylable/webpack-plugin --save-dev

    Install using yarn:

    yarn add @stylable/webpack-plugin --dev

    Sample dev config:

    // webpack.config.js
    module.exports = {
      plugins: [new StylableWebpackPlugin()]

    Plugin Configuration Options

    Some of the default values given to configuration parameters depend on what environment mode is currently active in webpack (development or production). Below you can see the various possible configuration parameters.

    interface StylableWebpackPluginOptions {
         * Filename of the output bundle when emitting css bundle
         * supports 
         * - [contenthash] replacer - "stylable.[contenthash].css" - based on file content hash
         * - [name] replacer - "[name].css" - based on entry name - is not supported in "extractMode: 'single'" with multiple entries
        filename?: string;
         * Determine the way css is injected to the document
         * js - every js module contains the css and inject it independently
         * css - emit bundled css asset to injected via link
         * mini-css - inject css modules via webpack mini-css-extract-plugin (can support dynamic splitting but order is not deterministic, requires minimum version 1.3.9)
         * none - will not generate any output css (usually good for ssr bundles)
        cssInjection?: 'js' | 'css' | 'mini-css' | 'none';
         * Determine the runtime stylesheet id kind used by the cssInjection js mode
        runtimeStylesheetId?: 'module' | 'namespace';
         * Config how error and warning reported to webpack by stylable
         * auto - Stylable warning will emit Webpack warning and Stylable error will emit Webpack error
         * strict - Stylable error and warning will emit Webpack error
         * loose - Stylable error and warning will emit Webpack warning
        diagnosticsMode?: 'auto' | 'strict' | 'loose';
         * Target of the js module
         * oldie - ES3 compatible
         * modern - ES2105 compatible
        target?: 'oldie' | 'modern';
         * Set the <style> tag st_id attribute to allow multiple Stylable build to be separated in the head
         * This only apply to cssInjection js mode
        runtimeId?: string;
         * Optimization options
        optimize?: {
            /* Removes comments from output css */
            removeComments?: boolean;
            /* Removes all Stylable directives like -st-extends */
            removeStylableDirectives?: boolean;
            /* Removes unused rules that target unused components */
            removeUnusedComponents?: boolean;
            /* Remove empty css rules */
            removeEmptyNodes?: boolean;
            /* Generate short classnames */
            classNameOptimizations?: boolean;
            /* Generate short namespaces */
            shortNamespaces?: boolean;
            /* Should minify css */
            minify?: boolean
         * Provide custom StylableOptimizer instance
        optimizer?: StylableOptimizer;
         * A function to override Stylable instance default configuration options
        stylableConfig?: (config: StylableConfig, compiler: Compiler) => StylableConfig;
         * Allow to disable specific diagnostics reports
        unsafeMuteDiagnostics?: {
            DUPLICATE_MODULE_NAMESPACE?: boolean | 'warn';
         * Runs "stc" programmatically with the webpack compilation.
         * true - it will automatically detect the closest "stylable.config.js" file and use it.
         * string - it will use the provided string as the "stcConfig" file path.
        stcConfig?: boolean | string;
         * Set the strategy of how to spit the extracted css
         * This option is only used when cssInjection is set to 'css'
         * single - extract all css to a single file
         * entries - extract file per entry which does not depend on another entry
        extractMode?: 'single' | 'entries';
         * Allow filter for url asset processing.
         * Filtered asset will not be processed and remain untouched.
        assetFilter?: (url: string, context: string) => boolean;

    Stylable config

    StylableWebpackPlugin will attempt to load the nearest stylable.config.js file and use it as override. Stylable config file should export webpackPlugin function with the following type:

    type webpackPlugin = (pluginOptions: StylableWebpackPluginOptions) => StylableWebpackPluginOptions;

    Example of a stylable.config.js file:

    module.exports.webpackPlugin = (defaultPluginOptions) => {
      return {
        stylableConfig(defaultStylableConfig) {
          return {
            // Example override the namespace generation strategy
            // resolveNamespace: (ns)=> `prefix-${ns}` 
        // Example to unsafely ignore duplicate namespace errors 
        // unsafeMuteDiagnostics: {
        // }

    Default development configuration

    new StylableWebpackPlugin({ 
        filename: 'stylable.css',
        cssInjection: 'js',
        runtimeStylesheetId: 'module',
        diagnosticsMode: 'auto',
        optimize: {
          removeUnusedComponents: true,
          removeStylableDirectives: true,
          removeComments: false,
          classNameOptimizations: false,
          shortNamespaces: false,
          removeEmptyNodes: false,
          minify: false,

    Default production configuration

    new StylableWebpackPlugin({ 
        filename: 'stylable.css',
        cssInjection: 'css',
        runtimeStylesheetId: 'namespace',
        diagnosticsMode: 'auto',
        optimize: {
          removeUnusedComponents: true,
          removeStylableDirectives: true,
          removeComments: true,
          classNameOptimizations: true,
          shortNamespaces: true,
          removeEmptyNodes: true,
          minify: true,

    Note: the values above reflect the defaults given to each parameter, they only need to be specified if the default value needs to be changed

    Asset handling

    CSS assets are handled by webpack native AssetsModules support.

    Compatibilities with existing loading mechanisms

    If you're using css_loader/extract make sure to exclude .st.css files from the process. You cannot use loaders with Stylable .st.css files


    In what cases should I provide a custom Optimizer?

    • You want to have different className and namespace short prefixes when you combine two projects that are not built together
    • You want to override the minify function and use a custom minifier

    When should I provide assetFilter?

    • When your webpack compilation should not handle a specific asset. For example, in NextJS all assets are already processed for you and the URLs in the CSS are not touched.


    Copyright (c) 2017 Ltd. All Rights Reserved. Use of this source code is governed by an MIT license.




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