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# mini-css-extract-plugin
This plugin extracts CSS into separate files. It creates a CSS file per JS file which contains CSS. It supports On-Demand-Loading of CSS and SourceMaps.
It builds on top of a new webpack v4 feature (module types) and requires webpack 4 to work.
Compared to the extract-text-webpack-plugin:
- Async loading
- No duplicate compilation (performance)
- Easier to use
- Specific to CSS
## Getting Started
To begin, you'll need to install `mini-css-extract-plugin`:
```bash
npm install --save-dev mini-css-extract-plugin
```
It's recommended to combine `mini-css-extract-plugin` with the [`css-loader`](https://github.com/webpack-contrib/css-loader)
Then add the loader and the plugin to your `webpack` config. For example:
**style.css**
```css
body {
background: green;
}
```
**component.js**
```js
import './style.css';
```
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [new MiniCssExtractPlugin()],
module: {
rules: [
{
test: /\.css$/i,
use: [MiniCssExtractPlugin.loader, 'css-loader'],
},
],
},
};
```
## Options
### Plugin Options
| Name | Type | Default | Description |
| :-----------------------------------: | :------------------: | :-----------------------------------: | :--------------------------------------------------------- |
| **[`filename`](#filename)** | `{String\|Function}` | `[name].css` | This option determines the name of each output CSS file |
| **[`chunkFilename`](#chunkFilename)** | `{String\|Function}` | `based on filename` | This option determines the name of non-entry chunk files |
| **[`ignoreOrder`](#ignoreOrder)** | `{Boolean}` | `false` | Remove Order Warnings |
| **[`insert`](#insert)** | `{String\|Function}` | `document.head.appendChild(linkTag);` | Inserts `` at the given position |
| **[`attributes`](#attributes)** | `{Object}` | `{}` | Adds custom attributes to tag |
| **[`linkType`](#linkType)** | `{String\|Boolean}` | `text/css` | Allows loading asynchronous chunks with a custom link type |
#### `filename`
Type: `String|Function`
Default: `[name].css`
This option determines the name of each output CSS file.
Works like [`output.filename`](https://webpack.js.org/configuration/output/#outputfilename)
#### `chunkFilename`
Type: `String|Function`
Default: `based on filename`
> i Specifying `chunkFilename` as a `function` is only available in webpack@5
This option determines the name of non-entry chunk files.
Works like [`output.chunkFilename`](https://webpack.js.org/configuration/output/#outputchunkfilename)
#### `ignoreOrder`
Type: `Boolean`
Default: `false`
Remove Order Warnings.
See [examples](#remove-order-warnings) below for details.
#### `insert`
Type: `String|Function`
Default: `document.head.appendChild(linkTag);`
By default, the `mini-css-extract-plugin` appends styles (`` elements) to `document.head` of the current `window`.
However in some circumstances it might be necessary to have finer control over the append target or even delay `link` elements instertion.
For example this is the case when you asynchronously load styles for an application that runs inside of an iframe.
In such cases `insert` can be configured to be a function or a custom selector.
If you target an [iframe](https://developer.mozilla.org/en-US/docs/Web/API/HTMLIFrameElement) make sure that the parent document has sufficient access rights to reach into the frame document and append elements to it.
##### `String`
Allows to setup custom [query selector](https://developer.mozilla.org/en-US/docs/Web/API/Document/querySelector).
A new `` element will be inserted after the found item.
**webpack.config.js**
```js
new MiniCssExtractPlugin({
insert: '#some-element',
});
```
A new `` element will be inserted after the element with id `some-element`.
##### `Function`
Allows to override default behavior and insert styles at any position.
> ⚠ Do not forget that this code will run in the browser alongside your application. Since not all browsers support latest ECMA features like `let`, `const`, `arrow function expression` and etc we recommend you to use only ECMA 5 features and syntax.
> > ⚠ The `insert` function is serialized to string and passed to the plugin. This means that it won't have access to the scope of the webpack configuration module.
**webpack.config.js**
```js
new MiniCssExtractPlugin({
insert: function (linkTag) {
var reference = document.querySelector('#some-element');
if (reference) {
reference.parentNode.insertBefore(linkTag, reference);
}
},
});
```
A new `` element will be inserted before the element with id `some-element`.
#### `attributes`
Type: `Object`
Default: `{}`
If defined, the `mini-css-extract-plugin` will attach given attributes with their values on element.
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [
new MiniCssExtractPlugin({
attributes: {
id: 'target',
'data-target': 'example',
},
}),
],
module: {
rules: [
{
test: /\.css$/i,
use: [MiniCssExtractPlugin.loader, 'css-loader'],
},
],
},
};
```
Note: It's only applied to dynamically loaded css chunks, if you want to modify link attributes inside html file, please using [html-webpack-plugin](https://github.com/jantimon/html-webpack-plugin)
#### `linkType`
Type: `String|Boolean`
Default: `text/css`
This option allows loading asynchronous chunks with a custom link type, such as .
##### `String`
Possible values: `text/css`
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [
new MiniCssExtractPlugin({
linkType: 'text/css',
}),
],
module: {
rules: [
{
test: /\.css$/i,
use: [MiniCssExtractPlugin.loader, 'css-loader'],
},
],
},
};
```
##### `Boolean`
`false` disables the link `type` attribute
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [
new MiniCssExtractPlugin({
linkType: false,
}),
],
module: {
rules: [
{
test: /\.css$/i,
use: [MiniCssExtractPlugin.loader, 'css-loader'],
},
],
},
};
```
### Loader Options
| Name | Type | Default | Description |
| :-----------------------------: | :------------------: | :--------------------------------: | :-------------------------------------------------------------------------------- |
| **[`publicPath`](#publicPath)** | `{String\|Function}` | `webpackOptions.output.publicPath` | Specifies a custom public path for the external resources like images, files, etc |
| **[`esModule`](#esModule)** | `{Boolean}` | `true` | Use ES modules syntax |
| **[`modules`](#modules)** | `{Object}` | `undefined` | Configuration CSS Modules |
#### `publicPath`
Type: `String|Function`
Default: the `publicPath` in `webpackOptions.output`
Specifies a custom public path for the external resources like images, files, etc inside `CSS`.
Works like [`output.publicPath`](https://webpack.js.org/configuration/output/#outputpublicpath)
##### `String`
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [
new MiniCssExtractPlugin({
// Options similar to the same options in webpackOptions.output
// both options are optional
filename: '[name].css',
chunkFilename: '[id].css',
}),
],
module: {
rules: [
{
test: /\.css$/,
use: [
{
loader: MiniCssExtractPlugin.loader,
options: {
publicPath: '/public/path/to/',
},
},
'css-loader',
],
},
],
},
};
```
##### `Function`
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [
new MiniCssExtractPlugin({
// Options similar to the same options in webpackOptions.output
// both options are optional
filename: '[name].css',
chunkFilename: '[id].css',
}),
],
module: {
rules: [
{
test: /\.css$/,
use: [
{
loader: MiniCssExtractPlugin.loader,
options: {
publicPath: (resourcePath, context) => {
return path.relative(path.dirname(resourcePath), context) + '/';
},
},
},
'css-loader',
],
},
],
},
};
```
#### `esModule`
Type: `Boolean`
Default: `true`
By default, `mini-css-extract-plugin` generates JS modules that use the ES modules syntax.
There are some cases in which using ES modules is beneficial, like in the case of [module concatenation](https://webpack.js.org/plugins/module-concatenation-plugin/) and [tree shaking](https://webpack.js.org/guides/tree-shaking/).
You can enable a CommonJS syntax using:
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [new MiniCssExtractPlugin()],
module: {
rules: [
{
test: /\.css$/i,
use: [
{
loader: MiniCssExtractPlugin.loader,
options: {
esModule: false,
},
},
'css-loader',
],
},
],
},
};
```
#### `modules`
Type: `Object`
Default: `undefined`
Configuration CSS Modules.
##### `namedExport`
Type: `Boolean`
Default: `false`
Enables/disables ES modules named export for locals.
> ⚠ Names of locals are converted to `camelCase`.
> ⚠ It is not allowed to use JavaScript reserved words in css class names.
> ⚠ Options `esModule` and `modules.namedExport` in `css-loader` and `MiniCssExtractPlugin.loader` should be enabled.
**styles.css**
```css
.foo-baz {
color: red;
}
.bar {
color: blue;
}
```
**index.js**
```js
import { fooBaz, bar } from './styles.css';
console.log(fooBaz, bar);
```
You can enable a ES module named export using:
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [new MiniCssExtractPlugin()],
module: {
rules: [
{
test: /\.css$/,
use: [
{
loader: MiniCssExtractPlugin.loader,
options: {
esModule: true,
modules: {
namedExport: true,
},
},
},
{
loader: 'css-loader',
options: {
esModule: true,
modules: {
namedExport: true,
localIdentName: 'foo__[name]__[local]',
},
},
},
],
},
],
},
};
```
## Examples
### Minimal example
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [
new MiniCssExtractPlugin({
// Options similar to the same options in webpackOptions.output
// all options are optional
filename: '[name].css',
chunkFilename: '[id].css',
ignoreOrder: false, // Enable to remove warnings about conflicting order
}),
],
module: {
rules: [
{
test: /\.css$/,
use: [
{
loader: MiniCssExtractPlugin.loader,
options: {
// you can specify a publicPath here
// by default it uses publicPath in webpackOptions.output
publicPath: '../',
},
},
'css-loader',
],
},
],
},
};
```
### Common use case
`mini-css-extract-plugin` is more often used in `production` mode to get separate css files.
For `development` mode (including `webpack-dev-server`) you can use `style-loader`, because it injects CSS into the DOM using multiple and works faster.
> i Do not use together `style-loader` and `mini-css-extract-plugin`.
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const devMode = process.env.NODE_ENV !== 'production';
const plugins = [];
if (!devMode) {
// enable in production only
plugins.push(new MiniCssExtractPlugin());
}
module.exports = {
plugins,
module: {
rules: [
{
test: /\.(sa|sc|c)ss$/,
use: [
devMode ? 'style-loader' : MiniCssExtractPlugin.loader,
'css-loader',
'postcss-loader',
'sass-loader',
],
},
],
},
};
```
### The `publicPath` option as function
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
module.exports = {
plugins: [
new MiniCssExtractPlugin({
// Options similar to the same options in webpackOptions.output
// both options are optional
filename: '[name].css',
chunkFilename: '[id].css',
}),
],
module: {
rules: [
{
test: /\.css$/,
use: [
{
loader: MiniCssExtractPlugin.loader,
options: {
publicPath: (resourcePath, context) => {
// publicPath is the relative path of the resource to the context
// e.g. for ./css/admin/main.css the publicPath will be ../../
// while for ./css/main.css the publicPath will be ../
return path.relative(path.dirname(resourcePath), context) + '/';
},
},
},
'css-loader',
],
},
],
},
};
```
### Advanced configuration example
This plugin should not be used with `style-loader` in the loaders chain.
Here is an example to have both HMR in `development` and your styles extracted in a file for `production` builds.
(Loaders options left out for clarity, adapt accordingly to your needs.)
You should not use `HotModuleReplacementPlugin` plugin if you are using a `webpack-dev-server`.
`webpack-dev-server` enables / disables HMR using `hot` option.
**webpack.config.js**
```js
const webpack = require('webpack');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const devMode = process.env.NODE_ENV !== 'production';
const plugins = [
new MiniCssExtractPlugin({
// Options similar to the same options in webpackOptions.output
// both options are optional
filename: devMode ? '[name].css' : '[name].[contenthash].css',
chunkFilename: devMode ? '[id].css' : '[id].[contenthash].css',
}),
];
if (devMode) {
// only enable hot in development
plugins.push(new webpack.HotModuleReplacementPlugin());
}
module.exports = {
plugins,
module: {
rules: [
{
test: /\.(sa|sc|c)ss$/,
use: [
MiniCssExtractPlugin.loader,
'css-loader',
'postcss-loader',
'sass-loader',
],
},
],
},
};
```
### Hot Module Reloading (HMR)
Note: HMR is automatically supported in webpack 5. No need to configure it. Skip the following:
The `mini-css-extract-plugin` supports hot reloading of actual css files in development.
Some options are provided to enable HMR of both standard stylesheets and locally scoped CSS or CSS modules.
Below is an example configuration of mini-css for HMR use with CSS modules.
You should not use `HotModuleReplacementPlugin` plugin if you are using a `webpack-dev-server`.
`webpack-dev-server` enables / disables HMR using `hot` option.
**webpack.config.js**
```js
const webpack = require('webpack');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const plugins = [
new MiniCssExtractPlugin({
// Options similar to the same options in webpackOptions.output
// both options are optional
filename: devMode ? '[name].css' : '[name].[contenthash].css',
chunkFilename: devMode ? '[id].css' : '[id].[contenthash].css',
}),
];
if (devMode) {
// only enable hot in development
plugins.push(new webpack.HotModuleReplacementPlugin());
}
module.exports = {
plugins,
module: {
rules: [
{
test: /\.css$/,
use: [
{
loader: MiniCssExtractPlugin.loader,
options: {},
},
'css-loader',
],
},
],
},
};
```
### Minimizing For Production
To minify the output, use a plugin like [css-minimizer-webpack-plugin](https://github.com/webpack-contrib/css-minimizer-webpack-plugin).
**webpack.config.js**
```js
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const CssMinimizerPlugin = require('css-minimizer-webpack-plugin');
module.exports = {
plugins: [
new MiniCssExtractPlugin({
filename: '[name].css',
chunkFilename: '[id].css',
}),
],
module: {
rules: [
{
test: /\.css$/,
use: [MiniCssExtractPlugin.loader, 'css-loader'],
},
],
},
optimization: {
minimizer: [
// For webpack@5 you can use the `...` syntax to extend existing minimizers (i.e. `terser-webpack-plugin`), uncomment the next line
// `...`,
new CssMinimizerPlugin(),
],
},
};
```
This will enable CSS optimization only in production mode. If you want to run it also in development set the `optimization.minimize` option to true.
### Using preloaded or inlined CSS
The runtime code detects already added CSS via `` or `
