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postcss-loader

Loader to process CSS with PostCSS.

Getting Started

You need webpack v5 to use the latest version. For Webpack v4, you have to install postcss-loader v4.

To begin, you'll need to install postcss-loader and postcss:

npm install --save-dev postcss-loader postcss

Then add the plugin to your webpack config. For example:

file.js

import css from "file.css";

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          "style-loader",
          "css-loader",
          {
            loader: "postcss-loader",
            options: {
              postcssOptions: {
                plugins: [
                  [
                    "postcss-preset-env",
                    {
                      // Options
                    },
                  ],
                ],
              },
            },
          },
        ],
      },
    ],
  },
};

Alternative use with config files:

postcss.config.js

module.exports = {
  plugins: [
    [
      "postcss-preset-env",
      {
        // Options
      },
    ],
  ],
};

The loader automatically searches for configuration files.

webpack.config.js

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

And run webpack via your preferred method.

Options

Name Type Default Description
execute {Boolean} undefined Enable PostCSS Parser support in CSS-in-JS
postcssOptions {Object|Function} defaults values for Postcss.process Set PostCSS options and plugins
sourceMap {Boolean} compiler.devtool Enables/Disables generation of source maps
implementation {Function|String} postcss Setup PostCSS implementation to use

execute

Type: Boolean Default: undefined

If you use JS styles the postcss-js parser, add the execute option.

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.style.js$/,
        use: [
          "style-loader",
          {
            loader: "css-loader",
          },
          {
            loader: "postcss-loader",
            options: {
              postcssOptions: {
                parser: "postcss-js",
              },
              execute: true,
            },
          },
        ],
      },
    ],
  },
};

postcssOptions

Type: Object|Function Default: undefined

Allows to set PostCSS options and plugins.

All PostCSS options are supported. There is the special config option for config files. How it works and how it can be configured is described below.

We recommend do not specify from, to and map options, because this can lead to wrong path in source maps. If you need source maps please use the sourcemap option.

Object

Setup plugins:

webpack.config.js (recommended)

const myOtherPostcssPlugin = require("postcss-my-plugin");
module.exports = {
  module: {
    rules: [
      {
        test: /\.sss$/i,
        loader: "postcss-loader",
        options: {
          postcssOptions: {
            plugins: [
              "postcss-import",
              ["postcss-short", { prefix: "x" }],
              require.resolve("my-postcss-plugin"),
              myOtherPostcssPlugin({ myOption: true }),
              // Deprecated and will be removed in the next major release
              { "postcss-nested": { preserveEmpty: true } },
            ],
          },
        },
      },
    ],
  },
};

webpack.config.js (deprecated, will be removed in the next major release)

module.exports = {
  module: {
    rules: [
      {
        test: /\.sss$/i,
        loader: "postcss-loader",
        options: {
          postcssOptions: {
            plugins: {
              "postcss-import": {},
              "postcss-short": { prefix: "x" },
            },
          },
        },
      },
    ],
  },
};

Setup syntax:

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.sss$/i,
        loader: "postcss-loader",
        options: {
          postcssOptions: {
            // Can be `String`
            syntax: "sugarss",
            // Can be `Object`
            syntax: require("sugarss"),
          },
        },
      },
    ],
  },
};

Setup parser:

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.sss$/i,
        loader: "postcss-loader",
        options: {
          postcssOptions: {
            // Can be `String`
            parser: "sugarss",
            // Can be `Object`
            parser: require("sugarss"),
            // Can be `Function`
            parser: require("sugarss").parse,
          },
        },
      },
    ],
  },
};

Setup stringifier:

webpack.config.js

const Midas = require("midas");
const midas = new Midas();

module.exports = {
  module: {
    rules: [
      {
        test: /\.sss$/i,
        loader: "postcss-loader",
        options: {
          postcssOptions: {
            // Can be `String`
            stringifier: "sugarss",
            // Can be `Object`
            stringifier: require("sugarss"),
            // Can be `Function`
            stringifier: midas.stringifier,
          },
        },
      },
    ],
  },
};

Function

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.(css|sss)$/i,
        loader: "postcss-loader",
        options: {
          postcssOptions: (loaderContext) => {
            if (/\.sss$/.test(loaderContext.resourcePath)) {
              return {
                parser: "sugarss",
                plugins: [
                  ["postcss-short", { prefix: "x" }],
                  "postcss-preset-env",
                ],
              };
            }

            return {
              plugins: [
                ["postcss-short", { prefix: "x" }],
                "postcss-preset-env",
              ],
            };
          },
        },
      },
    ],
  },
};

config

Type: Boolean|String Default: undefined

Allows to set options using config files. Options specified in the config file are combined with options passed to the loader, the loader options overwrite options from config.

Config Files

The loader will search up the directory tree for configuration in the following places:

  • a postcss property in package.json
  • a .postcssrc file in JSON or YAML format
  • a .postcssrc.json, .postcssrc.yaml, .postcssrc.yml, .postcssrc.js, or .postcssrc.cjs file
  • a postcss.config.js or postcss.config.cjs CommonJS module exporting an object (recommended)
Examples of Config Files

Using Object notation:

postcss.config.js (recommend)

module.exports = {
  // You can specify any options from https://postcss.org/api/#processoptions here
  // parser: 'sugarss',
  plugins: [
    // Plugins for PostCSS
    ["postcss-short", { prefix: "x" }],
    "postcss-preset-env",
  ],
};

Using Function notation:

postcss.config.js (recommend)

module.exports = (api) => {
  // `api.file` - path to the file
  // `api.mode` - `mode` value of webpack, please read https://webpack.js.org/configuration/mode/
  // `api.webpackLoaderContext` - loader context for complex use cases
  // `api.env` - alias `api.mode` for compatibility with `postcss-cli`
  // `api.options` - the `postcssOptions` options

  if (/\.sss$/.test(api.file)) {
    return {
      // You can specify any options from https://postcss.org/api/#processoptions here
      parser: "sugarss",
      plugins: [
        // Plugins for PostCSS
        ["postcss-short", { prefix: "x" }],
        "postcss-preset-env",
      ],
    };
  }

  return {
    // You can specify any options from https://postcss.org/api/#processoptions here
    plugins: [
      // Plugins for PostCSS
      ["postcss-short", { prefix: "x" }],
      "postcss-preset-env",
    ],
  };
};

postcss.config.js (deprecated, will be removed in the next major release)

module.exports = {
  // You can specify any options from https://postcss.org/api/#processoptions here
  // parser: 'sugarss',
  plugins: {
    // Plugins for PostCSS
    "postcss-short": { prefix: "x" },
    "postcss-preset-env": {},
  },
};
Config Cascade

You can use different postcss.config.js files in different directories. Config lookup starts from path.dirname(file) and walks the file tree upwards until a config file is found.

|– components
| |– component
| | |– index.js
| | |– index.png
| | |– style.css (1)
| | |– postcss.config.js (1)
| |– component
| | |– index.js
| | |– image.png
| | |– style.css (2)
|
|– postcss.config.js (1 && 2 (recommended))
|– webpack.config.js
|
|– package.json

After setting up your postcss.config.js, add postcss-loader to your webpack.config.js. You can use it standalone or in conjunction with css-loader (recommended).

Use it before css-loader and style-loader, but after other preprocessor loaders like e.g sass|less|stylus-loader, if you use any (since webpack loaders evaluate right to left/bottom to top).

webpack.config.js (recommended)

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          "style-loader",
          {
            loader: "css-loader",
            options: {
              importLoaders: 1,
            },
          },
          "postcss-loader",
        ],
      },
    ],
  },
};

Boolean

Enables/Disables autoloading config.

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        loader: "postcss-loader",
        options: {
          postcssOptions: {
            config: false,
          },
        },
      },
    ],
  },
};

String

Allows to specify the path to the config file.

webpack.config.js

const path = require("path");

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        loader: "postcss-loader",
        options: {
          postcssOptions: {
            config: path.resolve(__dirname, "custom.config.js"),
          },
        },
      },
    ],
  },
};

sourceMap

Type: Boolean Default: depends on the compiler.devtool value

Last updated Popular

v6.1.1

Install

npm install postcss-loader
yarn add postcss-loader

BUNDLE SIZE

Not Available

DOWNLOAD TIME

Not Available

CDNs

extras

Contributors

  • webpack-contrib