<div align="center">
  <img 
    width="180" 
    height="180" 
    hspace="10"
    alt="PostCSS Logo"
    src="https://api.postcss.org/logo.svg">
  <a href="https://github.com/webpack/webpack">
    <img 
      width="200" 
      height="200" 
      hspace="10"
      src="https://cdn.rawgit.com/webpack/media/e7485eb2/logo/icon.svg">
  </a>
  <div align="center">
    <a href="https://evilmartians.com/?utm_source=postcss">
      <img 
        src="https://evilmartians.com/badges/sponsored-by-evil-martians.svg"
        alt="Sponsored by Evil Martians" 
        width="236" 
        height="54" 
        vspace="10">
    </a>
  </div>
</div>

[![npm][npm]][npm-url]
[![node][node]][node-url]
[![tests][tests]][tests-url]
[![coverage][cover]][cover-url]
[![size][size]][size-url]

Webpack discussion: [![discussion][discussion]][discussion-url]

PostCSS chat: [![chat-postcss][chat-postcss]][chat-postcss-url]

# postcss-loader

A loader to process CSS using [`PostCSS`](https://github.com/postcss/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`:

```console
npm install --save-dev postcss-loader postcss
```

or

```console
yarn add -D postcss-loader postcss
```

or

```console
pnpm add -D postcss-loader postcss
```

Then add the loader to your `webpack` configuration. For example:

> In the following configuration the plugin [`postcss-preset-env`](https://github.com/csstools/postcss-preset-env) is used, which is not installed by default.

**file.js**

```js
import css from "file.css";
```

**webpack.config.js**

```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](#config):

**postcss.config.js**

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

The loader **automatically** searches for configuration files.

**webpack.config.js**

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

Finally, run `webpack` using the method you normally use (e.g., via CLI or an npm script).

## Options

- [`execute`](#execute)
- [`postcssOptions`](#postcssOptions)
- [`sourceMap`](#sourcemap)
- [`implementation`](#implementation)

### `execute`

Type:

```ts
type execute = boolean;
```

Default: `undefined`

Enable PostCSS parser support for `CSS-in-JS`.
If you use JS styles the [`postcss-js`](https://github.com/postcss/postcss-js) parser, add the `execute` option.

**webpack.config.js**

```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`

See the file [`./src/config.d.ts`](./src/config.d.ts).

Type:

```ts
import { type Config as PostCSSConfig } from "postcss-load-config";
import { type LoaderContext } from "webpack";

type PostCSSLoaderContext = LoaderContext<PostCSSConfig>;

interface PostCSSLoaderAPI {
  mode: PostCSSLoaderContext["mode"];
  file: PostCSSLoaderContext["resourcePath"];
  webpackLoaderContext: PostCSSLoaderContext;
  env: PostCSSLoaderContext["mode"];
  options: PostCSSConfig;
}

export type PostCSSLoaderOptions =
  | PostCSSConfig
  | ((api: PostCSSLoaderAPI) => PostCSSConfig);
```

Default: `undefined`

Allows you to set [`PostCSS options`](https://postcss.org/api/#processoptions) 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`](#sourcemap) option instead.

For large projects, to optimize performance of the loader, it is better to provide `postcssOptions` in loader config and specify `config: false`.
This approach removes the need to lookup and load external config files multiple times during compilation.

#### `object`

Setup `plugins`:

**webpack.config.js** (**recommended**)

```js
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)

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

Setup `syntax`:

**webpack.config.js**

<!-- eslint-skip -->

```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**

<!-- eslint-skip -->

```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**

<!-- eslint-skip -->

```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**

```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:

```ts
type config = boolean | string;
```

Default: `true`

Allows you 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**)

```js
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**)

```js
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)

```js
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 `postcss-loader` **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](https://webpack.js.org/concepts/loaders/#configuration)).

**webpack.config.js** (**recommended**)

```js
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**

```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**

```js
const path = require("node:path");

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

### `sourceMap`

Type:

```ts
type sourceMap = boolean;
```

Default: depends on the `compiler.devtool` value

By default generation of source maps depends on the [`devtool`](https://webpack.js.org/configuration/devtool/) option.
All values enable source map generation except `eval` and `false` value.

**webpack.config.js**

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

Alternative setup:

**webpack.config.js**

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

### `implementation`

Type:

```ts
type implementation = object;
```

type of `implementation` should be the same as [postcss.d.ts](https://github.com/postcss/postcss/blob/main/lib/postcss.d.ts)

Default: `postcss`

The special `implementation` option determines which implementation of PostCSS to use. Overrides the locally installed `peerDependency` version of `postcss`.

**This option is only really useful for downstream tooling authors to ease the PostCSS 7-to-8 transition.**

#### `function`

**webpack.config.js**

```js
module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          { loader: "style-loader" },
          { loader: "css-loader" },
          {
            loader: "postcss-loader",
            options: { implementation: require("postcss") },
          },
          { loader: "sass-loader" },
        ],
      },
    ],
  },
};
```

#### String

**webpack.config.js**

```js
module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          { loader: "style-loader" },
          { loader: "css-loader" },
          {
            loader: "postcss-loader",
            options: { implementation: require.resolve("postcss") },
          },
          { loader: "sass-loader" },
        ],
      },
    ],
  },
};
```

## Examples

### SugarSS

`SugarSS` is a whitespace-based syntax for PostCSS.

You'll need to install `sugarss`:

```console
npm install --save-dev sugarss
```

Using [`SugarSS`](https://github.com/postcss/sugarss) syntax.

**webpack.config.js**

```js
module.exports = {
  module: {
    rules: [
      {
        test: /\.sss$/i,
        use: [
          "style-loader",
          { loader: "css-loader", options: { importLoaders: 1 } },
          {
            loader: "postcss-loader",
            options: { postcssOptions: { parser: "sugarss" } },
          },
        ],
      },
    ],
  },
};
```

### Autoprefixer

You'll need to install `autoprefixer`:

```console
npm install --save-dev autoprefixer
```

Automatically add vendor prefixes to CSS rules using [`autoprefixer`](https://github.com/postcss/autoprefixer).

**webpack.config.js**

```js
module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          "style-loader",
          { loader: "css-loader", options: { importLoaders: 1 } },
          {
            loader: "postcss-loader",
            options: {
              postcssOptions: {
                plugins: [
                  [
                    "autoprefixer",
                    {
                      // Autoprefixer options (optional)
                    },
                  ],
                ],
              },
            },
          },
        ],
      },
    ],
  },
};
```

> [!WARNING]
>
> [`postcss-preset-env`](https://github.com/csstools/postcss-preset-env) includes [`autoprefixer`](https://github.com/postcss/autoprefixer), so adding it separately is not necessary if you already use the preset. More [information](https://github.com/csstools/postcss-preset-env#autoprefixer)

### PostCSS Preset Env

You'll need to install `postcss-preset-env`:

```console
npm install --save-dev postcss-preset-env
```

**webpack.config.js**

```js
module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          "style-loader",
          { loader: "css-loader", options: { importLoaders: 1 } },
          {
            loader: "postcss-loader",
            options: {
              postcssOptions: {
                plugins: [
                  [
                    "postcss-preset-env",
                    {
                      // Options
                    },
                  ],
                ],
              },
            },
          },
        ],
      },
    ],
  },
};
```

### CSS Modules

> What are `CSS Modules`? Please [read here](https://github.com/webpack-contrib/css-loader#modules).

No additional options required on the `postcss-loader` side to support CSS Modules.
To make them work properly, either add the `css-loader`’s `importLoaders` option.

**webpack.config.js**

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

### CSS-in-JS and [`postcss-js`](https://github.com/postcss/postcss-js)

To process styles written in JavaScript, you can use `postcss-js` as the parser.

You'll need to install `postcss-js`:

```console
npm install --save-dev postcss-js
```

If you want to process styles written in JavaScript, use the [`postcss-js`](https://github.com/postcss/postcss-js) parser.

**webpack.config.js**

```js
module.exports = {
  module: {
    rules: [
      {
        test: /\.style.js$/,
        use: [
          "style-loader",
          { loader: "css-loader", options: { importLoaders: 2 } },
          {
            loader: "postcss-loader",
            options: {
              postcssOptions: { parser: "postcss-js" },
              execute: true,
            },
          },
          "babel-loader",
        ],
      },
    ],
  },
};
```

As result you will be able to write styles in the following way:

```js
import colors from "./styles/colors";

export default {
  ".menu": { color: colors.main, height: 25, "&_link": { color: "white" } },
};
```

> [!WARNING]
>
> If you are using Babel you need to do the following in order for the setup to work
>
> 1. Add [`babel-plugin-add-module-exports`](https://github.com/59naga/babel-plugin-add-module-exports) to your configuration.
> 2. You need to have only one **default** export per style module.

### Extract CSS

To extract CSS into separate files, use [`mini-css-extract-plugin`](https://github.com/webpack-contrib/mini-css-extract-plugin).

**webpack.config.js**

```js
const isProductionMode = process.env.NODE_ENV === "production";

const MiniCssExtractPlugin = require("mini-css-extract-plugin");

module.exports = {
  mode: isProductionMode ? "production" : "development",
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          isProductionMode ? MiniCssExtractPlugin.loader : "style-loader",
          "css-loader",
          "postcss-loader",
        ],
      },
    ],
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: isProductionMode ? "[name].[contenthash].css" : "[name].css",
    }),
  ],
};
```

> 💡 Use this setup to extract and cache CSS in production while keeping fast style injection during development.

### Emit assets

To emit an asset from PostCSS plugin to the webpack, need to add a message in `result.messages`.

The message should contain the following fields:

- `type` = `asset` - Message type (require, should be equal `asset`)
- `file` - file name (require)
- `content` - file content (require)
- `sourceMap` - sourceMap
- `info` - asset info

**webpack.config.js**

```js
const postcssCustomPlugin = (opts = {}) => ({
  postcssPlugin: "postcss-custom-plugin",
  Once: (root, { result }) => {
    result.messages.push({
      type: "asset",
      file: "sprite.svg",
      content: "<svg>...</svg>",
    });
  },
});

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          "style-loader",
          "css-loader",
          {
            loader: "postcss-loader",
            options: { postcssOptions: { plugins: [postcssCustomPlugin()] } },
          },
        ],
      },
    ],
  },
};
```

> ℹ️ This allows your plugin to generate additional files as part of the build process, and Webpack will handle them like any other emitted asset.

### Add dependencies, contextDependencies, buildDependencies, missingDependencies

The dependencies are necessary for webpack to understand when it needs to run recompilation on the changed files.

There are two way to add dependencies:

1. (Recommended). The plugin may emit messages in `result.messages`.

The message should contain the following fields:

- `type` = `dependency` - Message type (require, should be equal `dependency`, `context-dependency`, `build-dependency` or `missing-dependency`)
- `file` - absolute file path (require)

**webpack.config.js**

```js
const path = require("node:path");

const postcssCustomPlugin = (opts = {}) => ({
  postcssPlugin: "postcss-custom-plugin",
  Once: (root, { result }) => {
    result.messages.push({
      type: "dependency",
      file: path.resolve(__dirname, "path", "to", "file"),
    });
  },
});

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: [
          "style-loader",
          "css-loader",
          {
            loader: "postcss-loader",
            options: { postcssOptions: { plugins: [postcssCustomPlugin()] } },
          },
        ],
      },
    ],
  },
};
```

> 💡 You can use ready-made plugin [postcss-add-dependencies](https://www.npmjs.com/package/postcss-add-dependencies) to simplify this process.

2. Pass `loaderContext` in plugin (for advanced setups).

**webpack.config.js**

```js
const path = require("node:path");

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

> ⚠️ Use this approach only when managing dependencies via custom PostCSS configurations with dynamic imports or external files.

**postcss.config.js**

Pass the `webpackLoaderContext` through the PostCSS `api` object:

```js
module.exports = (api) => ({
  plugins: [
    require("path/to/postcssCustomPlugin.js")({
      loaderContext: api.webpackLoaderContext,
    }),
  ],
});
```

**postcssCustomPlugin.js**

Register a file dependency using `loaderContext.addDependency`:

```js
const path = require("node:path");

const postcssCustomPlugin = (opts = {}) => ({
  postcssPlugin: "postcss-custom-plugin",
  Once: (root, { result }) => {
    opts.loaderContext.addDependency(
      path.resolve(__dirname, "path", "to", "file"),
    );
  },
});

postcssCustomPlugin.postcss = true;

module.exports = postcssCustomPlugin;
```

> ✅ This method is ideal when you want to dynamically declare dependencies without relying on result.messages, especially in more complex setups or shared plugin configurations.

## Contributing

We welcome all contributions!
If you're new here, please take a moment to review our contributing guidelines before submitting issues or pull requests.

[CONTRIBUTING](./.github/CONTRIBUTING.md)

## License

[MIT](./LICENSE)

[npm]: https://img.shields.io/npm/v/postcss-loader.svg
[npm-url]: https://npmjs.com/package/postcss-loader
[node]: https://img.shields.io/node/v/postcss-loader.svg
[node-url]: https://nodejs.org
[tests]: https://github.com/webpack-contrib/postcss-loader/workflows/postcss-loader/badge.svg
[tests-url]: https://github.com/webpack-contrib/postcss-loader/actions
[cover]: https://codecov.io/gh/webpack-contrib/postcss-loader/branch/master/graph/badge.svg
[cover-url]: https://codecov.io/gh/webpack-contrib/postcss-loader
[discussion]: https://img.shields.io/github/discussions/webpack/webpack
[discussion-url]: https://github.com/webpack/webpack/discussions
[chat-postcss]: https://badges.gitter.im/postcss/postcss.svg
[chat-postcss-url]: https://gitter.im/postcss/postcss
[size]: https://packagephobia.now.sh/badge?p=postcss-loader
[size-url]: https://packagephobia.now.sh/result?p=postcss-loader
