width="180"
height="180"
hspace="10"
alt="PostCSS Logo"
src="https://api.postcss.org/logo.svg">

width="200"
height="200"
hspace="10"
src="https://cdn.rawgit.com/webpack/media/e7485eb2/logo/icon.svg">

src="https://evilmartians.com/badges/sponsored-by-evil-martians.svg"
alt="Sponsored by Evil Martians"
width="236"
height="54"
vspace="10">

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

Webpack chat: [![chat][chat]][chat-url]

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

postcss-loader

Loader to process CSS with PostCSS.

Getting Started

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

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

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

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:

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"],
},
],
},
};
`

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 |

$3

Type: Boolean
Default: undefined

If you use JS styles the 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,
},
},
],
},
],
},
};
`

$3

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)

`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

`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

`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

`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: 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)

`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 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)

`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("path");

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

$3

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

By default generation of source maps depends on the 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" },
],
},
],
},
};
`

$3

Type: Function
Default: undefined

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.

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" },
],
},
],
},
};
`

Examples

$3

You'll need to install sugarss:

`console
npm install --save-dev sugarss
`

Using 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",
},
},
},
],
},
],
},
};
`

$3

You'll need to install autoprefixer:

`console
npm install --save-dev autoprefixer
`

Add vendor prefixes to CSS rules using 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",
{
// Options
},
],
],
},
},
},
],
},
],
},
};
`

> :warning: postcss-preset-env includes autoprefixer, so adding it separately is not necessary if you already use the preset. More information

$3

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
},
],
],
},
},
},
],
},
],
},
};
`

$3

What is CSS Modules? Please read.

No additional options required on the postcss-loader side.
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",
],
},
],
},
};
`

$3

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 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 to your configuration.
> 2. You need to have only one default export per style module.

$3

Using 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",
}),
],
};
`

$3

To write a 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 customPlugin = () => (css, result) => {
result.messages.push({
type: "asset",
file: "sprite.svg",
content: "",
});
};

const postcssPlugin = postcss.plugin("postcss-assets", customPlugin);

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

$3

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)
- file - absolute file path (require)

webpack.config.js

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

const customPlugin = () => (css, result) => {
result.messages.push({
type: "dependency",
file: path.resolve(__dirname, "path", "to", "file"),
});
};

const postcssPlugin = postcss.plugin("postcss-assets", customPlugin);

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

2. Pass loaderContext in plugin.

webpack.config.js

`js
const path = require("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"),
},
},
},
],
},
],
},
};
`

postcss.config.js

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

customPlugin.js

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

const customPlugin = (loaderContext) => (css, result) => {
loaderContext.webpack.addDependency(
path.resolve(__dirname, "path", "to", "file")
);
};

module.exports = postcss.plugin("postcss-assets", customPlugin);
``

Contributing

Please take a moment to read our contributing guidelines if you haven't yet done so.

CONTRIBUTING

License

MIT

[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
[deps]: https://david-dm.org/webpack-contrib/postcss-loader.svg
[deps-url]: https://david-dm.org/webpack-contrib/postcss-loader
[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
[chat]: https://badges.gitter.im/webpack/webpack.svg
[chat-url]: https://gitter.im/webpack/webpack
[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