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    CSS Loader

    Install

    npm install --save-dev css-loader

    Usage

    The css-loader interprets @import and url() like import/require() and will resolve them.

    Good loaders for requiring your assets are the file-loader and the url-loader which you should specify in your config (see below).

    file.js

    import css from 'file.css';

    webpack.config.js

    module.exports = {
      module: {
        rules: [
          {
            test: /\.css$/,
            use: [ 'style-loader', 'css-loader' ]
          }
        ]
      }
    }

    toString

    You can also use the css-loader results directly as string, such as in Angular's component style.

    webpack.config.js

    {
       test: /\.css$/,
       use: [
         'to-string-loader',
         'css-loader'
       ]
    }

    or

    const css = require('./test.css').toString();
     
    console.log(css); // {String}

    If there are SourceMaps, they will also be included in the result string.

    If, for one reason or another, you need to extract CSS as a plain string resource (i.e. not wrapped in a JS module) you might want to check out the extract-loader. It's useful when you, for instance, need to post process the CSS as a string.

    webpack.config.js

    {
       test: /\.css$/,
       use: [
         'handlebars-loader', // handlebars loader expects raw resource string
         'extract-loader',
         'css-loader'
       ]
    }

    Options

    Name Type Default Description
    root {String} / Path to resolve URLs, URLs starting with / will not be translated
    url {Boolean} true Enable/Disable url() handling
    alias {Object} {} Create aliases to import certain modules more easily
    import {Boolean} true Enable/Disable @import handling
    modules {Boolean} false Enable/Disable CSS Modules
    minimize {Boolean\|Object} false Enable/Disable minification
    sourceMap {Boolean} false Enable/Disable Sourcemaps
    camelCase {Boolean\|String} false Export Classnames in CamelCase
    importLoaders {Number} 0 Number of loaders applied before CSS loader
    localIdentName {String} [hash:base64] Configure the generated ident

    root

    For URLs that start with a /, the default behavior is to not translate them.

    url(/image.png) => url(/image.png)

    If a root query parameter is set, however, it will be prepended to the URL and then translated.

    webpack.config.js

    {
      loader: 'css-loader',
      options: { root: '.' }
    }

    url(/image.png) => require('./image.png')

    Using 'Root-relative' urls is not recommended. You should only use it for legacy CSS files.

    url

    To disable url() resolving by css-loader set the option to false.

    To be compatible with existing css files (if not in CSS Module mode).

    url(image.png) => require('./image.png')
    url(~module/image.png) => require('module/image.png')
    

    alias

    Rewrite your urls with alias, this is useful when it's hard to change url paths of your input files, for example, when you're using some css / sass files in another package (bootstrap, ratchet, font-awesome, etc.).

    css-loader's alias follows the same syntax as webpack's resolve.alias, you can see the details at the resolve docs

    file.scss

    @charset "UTF-8";
    @import "bootstrap";

    webpack.config.js

    {
      test: /\.scss$/,
      use: [
        {
          loader: "style-loader"
        },
        {
          loader: "css-loader",
          options: {
            alias: {
              "../fonts/bootstrap": "bootstrap-sass/assets/fonts/bootstrap"
            }
          }
        },
        {
          loader: "sass-loader",
          options: {
            includePaths: [
              path.resolve("./node_modules/bootstrap-sass/assets/stylesheets")
            ]
          }
        }
      ]
    }

    Check out this working bootstrap example.

    import

    To disable @import resolving by css-loader set the option to false

    @import url('https://fonts.googleapis.com/css?family=Roboto');

    ⚠️ Use with caution, since this disables resolving for all @imports, including css modules composes: xxx from 'path/to/file.css' feature.

    modules

    The query parameter modules enables the CSS Modules spec.

    This enables local scoped CSS by default. (You can switch it off with :global(...) or :global for selectors and/or rules.).

    Scope

    By default CSS exports all classnames into a global selector scope. Styles can be locally scoped to avoid globally scoping styles.

    The syntax :local(.className) can be used to declare className in the local scope. The local identifiers are exported by the module.

    With :local (without brackets) local mode can be switched on for this selector. :global(.className) can be used to declare an explicit global selector. With :global (without brackets) global mode can be switched on for this selector.

    The loader replaces local selectors with unique identifiers. The choosen unique identifiers are exported by the module.

    :local(.className{ background: red; }
    :local .className { color: green; }
    :local(.className .subClass{ color: green; }
    :local .className .subClass :global(.global-class-name{ color: blue; }
    ._23_aKvs-b8bW2Vg3fwHozO { background: red; }
    ._23_aKvs-b8bW2Vg3fwHozO { color: green; }
    ._23_aKvs-b8bW2Vg3fwHozO ._13LGdX8RMStbBE9w-t0gZ1 { color: green; }
    ._23_aKvs-b8bW2Vg3fwHozO ._13LGdX8RMStbBE9w-t0gZ1 .global-class-name { color: blue; }

    ℹ️ Identifiers are exported

    exports.locals = {
      className: '_23_aKvs-b8bW2Vg3fwHozO',
      subClass: '_13LGdX8RMStbBE9w-t0gZ1'
    }

    CamelCase is recommended for local selectors. They are easier to use in the within the imported JS module.

    url() URLs in block scoped (:local .abc) rules behave like requests in modules.

    file.png => ./file.png
    ~module/file.png => module/file.png
    

    You can use :local(#someId), but this is not recommended. Use classes instead of ids. You can configure the generated ident with the localIdentName query parameter (default [hash:base64]).

    webpack.config.js

    {
     test: /\.css$/,
     use: [
       {
         loader: 'css-loader',
         options: {
           modules: true,
           localIdentName: '[path][name]__[local]--[hash:base64:5]'
         }
       }
     ]
    }

    You can also specify the absolute path to your custom getLocalIdent function to generate classname based on a different schema. This requires webpack >= 2.2.1 (it supports functions in the options object).

    webpack.config.js

    {
      loader: 'css-loader',
      options: {
        modules: true,
        localIdentName: '[path][name]__[local]--[hash:base64:5]',
        getLocalIdent: (context, localIdentName, localName, options) => {
          return 'whatever_random_class_name'
        }
      }
    }

    ℹ️ For prerendering with extract-text-webpack-plugin you should use css-loader/locals instead of style-loader!css-loader in the prerendering bundle. It doesn't embed CSS but only exports the identifier mappings.

    Composing

    When declaring a local classname you can compose a local class from another local classname.

    :local(.className{
      background: red;
      color: yellow;
    }
     
    :local(.subClass{
      composes: className;
      background: blue;
    }

    This doesn't result in any change to the CSS itself but exports multiple classnames.

    exports.locals = {
      className: '_23_aKvs-b8bW2Vg3fwHozO',
      subClass: '_13LGdX8RMStbBE9w-t0gZ1 _23_aKvs-b8bW2Vg3fwHozO'
    }
    ._23_aKvs-b8bW2Vg3fwHozO {
      background: red;
      color: yellow;
    }
     
    ._13LGdX8RMStbBE9w-t0gZ1 {
      background: blue;
    }

    Importing

    To import a local classname from another module.

    :local(.continueButton{
      composes: button from 'library/button.css';
      background: red;
    }
    :local(.nameEdit{
      composes: edit highlight from './edit.css';
      background: red;
    }

    To import from multiple modules use multiple composes: rules.

    :local(.className{
      composes: edit hightlight from './edit.css';
      composes: button from 'module/button.css';
      composes: classFromThisModule;
      background: red;
    }

    minimize

    By default the css-loader minimizes the css if specified by the module system.

    In some cases the minification is destructive to the css, so you can provide your own options to the cssnano-based minifier if needed. See cssnano's documentation for more information on the available options.

    You can also disable or enforce minification with the minimize query parameter.

    webpack.config.js

    {
      loader: 'css-loader',
      options: {
        minimize: true || {/* CSSNano Options */}
      }
    }

    sourceMap

    To include source maps set the sourceMap option.

    I. e. the extract-text-webpack-plugin can handle them.

    They are not enabled by default because they expose a runtime overhead and increase in bundle size (JS source maps do not). In addition to that relative paths are buggy and you need to use an absolute public path which include the server URL.

    webpack.config.js

    {
      loader: 'css-loader',
      options: {
        sourceMap: true
      }
    }

    camelCase

    By default, the exported JSON keys mirror the class names. If you want to camelize class names (useful in JS), pass the query parameter camelCase to css-loader.

    Name Type Description
    true {Boolean} Class names will be camelized
    'dashes' {String} Only dashes in class names will be camelized
    'only' {String} Introduced in 0.27.1. Class names will be camelized, the original class name will be removed from the locals
    'dashesOnly' {String} Introduced in 0.27.1. Dashes in class names will be camelized, the original class name will be removed from the locals

    file.css

    .class-name {}

    file.js

    import { className } from 'file.css';

    webpack.config.js

    {
      loader: 'css-loader',
      options: {
        camelCase: true
      }
    }

    importLoaders

    The query parameter importLoaders allows to configure how many loaders before css-loader should be applied to @imported resources.

    webpack.config.js

    {
      test: /\.css$/,
      use: [
        'style-loader',
        {
          loader: 'css-loader',
          options: {
            importLoaders: 2 // 0 => no loaders (default); 1 => postcss-loader; 2 => postcss-loader, sass-loader
          }
        },
        'postcss-loader',
        'sass-loader'
      ]
    }

    This may change in the future, when the module system (i. e. webpack) supports loader matching by origin.

    Examples

    Assets

    The following webpack.config.js can load CSS files, embed small PNG/JPG/GIF/SVG images as well as fonts as Data URLs and copy larger files to the output directory.

    webpack.config.js

    module.exports = {
      module: {
        rules: [
          {
            test: /\.css$/,
            use: [ 'style-loader', 'css-loader' ]
          },
          {
            test: /\.(png|jpg|gif|svg|eot|ttf|woff|woff2)$/,
            loader: 'url-loader',
            options: {
              limit: 10000
            }
          }
        ]
      }
    }

    Extract

    For production builds it's recommended to extract the CSS from your bundle being able to use parallel loading of CSS/JS resources later on. This can be achieved by using the extract-text-webpack-plugin to extract the CSS when running in production mode.

    webpack.config.js

    const env = process.env.NODE_ENV
     
    const ExtractTextPlugin = require('extract-text-webpack-plugin')
     
    module.exports = {
      module: {
        rules: [
          {
            test: /\.css$/,
            use: env === 'production'
              ? ExtractTextPlugin.extract({
                  fallback: 'style-loader',
                  use: [ 'css-loader' ]
              })
              : [ 'style-loader', 'css-loader' ]
          },
        ]
      },
      plugins: env === 'production'
        ? [
            new ExtractTextPlugin({
              filename: '[name].css'
            })
          ]
        : []
    }

    Maintainers


    Juho Vepsäläinen

    Joshua Wiens

    Kees Kluskens

    Sean Larkin

    Michael Ciniawsky

    Evilebot Tnawi

    Joscha Feth

    Keywords

    none

    install

    npm i css-loader

    Downloadsweekly downloads

    2,274,792

    version

    0.28.11

    license

    MIT

    repository

    github.com

    last publish

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