PostCSS loader for webpack to postprocesses your CSS with PostCSS plugins.
npm install postcss-loader --save-devYou can configure PostCSS Loader in common PostCSS config or directly in Webpack config. Common PostCSS config is recommended way, because many PostCSS tools will be able to share it.
Add PostCSS Loader to webpack.config.js. Put it before css-loader
and style-loader. But after sass-loader, if you use it.
module.exports = {
module: {
loaders: [
{
test: /\.css$/,
loaders: [
'style-loader',
'css-loader?importLoaders=1',
'postcss-loader'
]
}
]
}
}Then create postcss.config.js:
module.exports = {
plugins: [
require('precss'),
require('autoprefixer')
]
}You could put different configs in different directories. For example,
global config in project/postcss.config.js and override its plugins
in project/src/legacy/postcss.config.js.
You can read more about common PostCSS config in postcss-load-config.
module.exports = {
module: {
rules: [
{
test: /\.css$/,
use: [
'style-loader',
{
loader: 'css-loader',
options: { importLoaders: 1 }
},
{
loader: 'postcss-loader',
options: {
plugins: function () {
return [
require('precss'),
require('autoprefixer')
];
}
}
}
]
}
]
}
}module.exports = {
module: {
loaders: [
{
test: /\.css$/,
loaders: [
'style-loader',
'css-loader?importLoaders=1',
'postcss-loader'
]
}
]
},
postcss: function () {
return [
require('precss'),
require('autoprefixer')
];
}
}We don’t recommend to put Autoprefixer’s browsers to plugin options.
Webpack css-loader contains cssnano. It uses Autoprefixer too.
As result you will have different browsers in Autoprefixer
and CSS minification. At result, css-loader could clean some prefixes
in production.
We recommend to put browsers in browserslist config in project root:
last 2 versions
ie 11
As result other tools (for example, Stylelint) will use same browsers settings.
Also, please vote for disable second Autoprefixer in css-loader.
PostCSS can transforms styles in any syntax, not only in CSS. There are 3 parameters to control syntax:
syntaxaccepts module name withparseandstringifyfunction.parseraccepts module name with input parser function.stringifieraccepts module name with output stringifier function.
module.exports = {
module: {
loaders: [
{
test: /\.sss/,
loaders: [
'style-loader',
'css-loader?importLoaders=1',
'postcss-loader?parser=sugarss'
]
}
]
}
}Loader will use source map settings from previous loader.
You can set this sourceMap parameter to inline value to put source maps
into CSS annotation comment:
module.exports = {
module: {
loaders: [
{
test: '\/.css',
loaders: [
'style-loader',
'css-loader?importLoaders=1',
'postcss-loader?sourceMap=inline'
]
}
]
}
}This loader cannot be used with CSS Modules out of the box due
to the way css-loader processes file imports. To make them work properly,
either add the css-loader’s importLoaders option
…
{
test: /\.css$/,
loaders: [
'style-loader',
'css-loader?modules&importLoaders=1',
'postcss-loader'
]
}
…or use postcss-modules plugin instead of css-loader.
If you want to process styles written in JavaScript you can use the postcss-js parser.
…
{
test: /\.style.js$/,
loaders: [
'style-loader',
'css-loader?modules&importLoaders=1',
'postcss-loader?parser=postcss-js',
'babel'
]
}
…As result you will be able to write styles as:
import colors from './config/colors'
export default {
'.menu': {
color: colors.main,
height: 25,
'&_link': {
color: 'white'
}
}
}If you use JS styles without postcss-js parser, you can add exec parameter:
…
{
test: /\.style.xyz$/,
loaders: [
'style-loader',
'css-loader?modules&importLoaders=1',
'postcss-loader?parser=custom-parser&exec'
]
}
…Webpack provides webpack plugin developers a convenient way to hook into the build pipeline. The postcss-loader makes use of this event system to allow building integrated postcss-webpack tools.
See the example implementation.
Event postcss-loader-before-processing is fired before processing and allows
to add or remove postcss plugins.
