readmongo/node_modules/postcss-loader/README.md

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

<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>
  <h1>PostCSS Loader</h1>
  <p>Loader for <a href="https://webpack.js.org/">webpack</a> to process CSS with <a href="https://postcss.org/">PostCSS</a></p>
</div>

<h2 align="center">Install</h2>

```bash
npm i -D postcss-loader
```

<h2 align="center">Usage</h2>

### `Configuration`

**`postcss.config.js`**
```js
module.exports = {
  parser: 'sugarss',
  plugins: {
    'postcss-import': {},
    'postcss-preset-env': {},
    'cssnano': {}
  }
}
```

You can read more about common PostCSS Config [here](https://github.com/michael-ciniawsky/postcss-load-config).

### `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 **after** `css-loader` and `style-loader`, but **before** other preprocessor loaders like e.g `sass|less|stylus-loader`, if you use any.

**`webpack.config.js`**
```js
module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [ 'style-loader', 'postcss-loader' ]
      }
    ]
  }
}
```

> ⚠️  When `postcss-loader` is used standalone (without `css-loader`) don't use `@import` in your CSS, since this can lead to quite bloated bundles

**`webpack.config.js` (recommended)**
```js
module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          'style-loader',
          { loader: 'css-loader', options: { importLoaders: 1 } },
          'postcss-loader'
        ]
      }
    ]
  }
}
```

<h2 align="center">Options</h2>

|Name|Type|Default|Description|
|:--:|:--:|:-----:|:----------|
|[`exec`](#exec)|`{Boolean}`|`undefined`|Enable PostCSS Parser support in `CSS-in-JS`|
|[`parser`](#syntaxes)|`{String\|Object}`|`undefined`|Set PostCSS Parser|
|[`syntax`](#syntaxes)|`{String\|Object}`|`undefined`|Set PostCSS Syntax|
|[`stringifier`](#syntaxes)|`{String\|Object}`|`undefined`|Set PostCSS Stringifier|
|[`config`](#config)|`{Object}`|`undefined`|Set `postcss.config.js` config path && `ctx`|
|[`plugins`](#plugins)|`{Array\|Function}`|`[]`|Set PostCSS Plugins|
|[`sourceMap`](#sourcemap)|`{String\|Boolean}`|`false`|Enable Source Maps|

### `Exec`

If you use JS styles without the [`postcss-js`][postcss-js] parser, add the `exec` option.

**`webpack.config.js`**
```js
{
  test: /\.style.js$/,
  use: [
    'style-loader',
    { loader: 'css-loader', options: { importLoaders: 1 } },
    { loader: 'postcss-loader', options: { parser: 'sugarss', exec: true } }
  ]
}
```

### `Config`

|Name|Type|Default|Description|
|:--:|:--:|:-----:|:----------|
|[`path`](#path)|`{String}`|`undefined`|PostCSS Config Directory|
|[`context`](#context)|`{Object}`|`undefined`|PostCSS Config Context|

#### `Path`

You can manually specify the path to search for your config (`postcss.config.js`) with the `config.path` option. This is needed if you store your config  in a separate e.g `./config || ./.config` folder.

> ⚠️  Otherwise it is **unnecessary** to set this option and is **not** recommended

> ⚠️  Note that you **can't** use a **filename** other than the [supported config formats] (e.g `.postcssrc.js`, `postcss.config.js`), this option only allows you to manually specify the **directory** where config lookup should **start** from

**`webpack.config.js`**
```js
{
  loader: 'postcss-loader',
  options: {
    config: {
      path: 'path/to/.config/' ✅
      path: 'path/to/.config/css.config.js' ❌
    }
  }
}
```

[supported config formats]: https://github.com/michael-ciniawsky/postcss-load-config#usage

#### `Context (ctx)`

|Name|Type|Default|Description|
|:--:|:--:|:-----:|:----------|
|`env`|`{String}`|`'development'`|`process.env.NODE_ENV`|
|`file`|`{Object}`|`loader.resourcePath`|`extname`, `dirname`, `basename`|
|`options`|`{Object}`|`{}`|Options|

`postcss-loader` exposes context `ctx` to the config file, making your `postcss.config.js` dynamic, so can use it to do some real magic ✨

**`postcss.config.js`**
```js
module.exports = ({ file, options, env }) => ({
  parser: file.extname === '.sss' ? 'sugarss' : false,
  plugins: {
    'postcss-import': { root: file.dirname },
    'postcss-preset-env': options['postcss-preset-env'] ? options['postcss-preset-env'] : false,
    'cssnano': env === 'production' ? options.cssnano : false
  }
})
```

**`webpack.config.js`**
```js
{
  loader: 'postcss-loader',
  options: {
    config: {
      ctx: {
        'postcss-preset-env': {...options},
        cssnano: {...options},
      }
    }
  }
}
```

### `Plugins`

**`webpack.config.js`**
```js
{
  loader: 'postcss-loader',
  options: {
    ident: 'postcss',
    plugins: (loader) => [
      require('postcss-import')({ root: loader.resourcePath }),
      require('postcss-preset-env')(),
      require('cssnano')()
    ]
  }
}
```

> ⚠️  webpack requires an identifier (`ident`) in `options` when `{Function}/require` is used (Complex Options). The `ident` can be freely named as long as it is unique. It's recommended to name it (`ident: 'postcss'`)

### `Syntaxes`

|Name|Type|Default|Description|
|:--:|:--:|:-----:|:----------|
|[`parser`](#parser)|`{String\|Function}`|`undefined`|Custom PostCSS Parser|
|[`syntax`](#syntax)|`{String\|Function}`|`undefined`|Custom PostCSS Syntax|
|[`stringifier`](#stringifier)|`{String\|Function}`|`undefined`|Custom PostCSS Stringifier|

#### `Parser`

**`webpack.config.js`**
```js
{
  test: /\.sss$/,
  use: [
    ...,
    { loader: 'postcss-loader', options: { parser: 'sugarss' } }
  ]
}
```

#### `Syntax`

**`webpack.config.js`**
```js
{
  test: /\.css$/,
  use: [
    ...,
    { loader: 'postcss-loader', options: { syntax: 'sugarss' } }
  ]
}
```

#### `Stringifier`

**`webpack.config.js`**
```js
{
  test: /\.css$/,
  use: [
    ...,
    { loader: 'postcss-loader', options: { stringifier: 'midas' } }
  ]
}
```

### `SourceMap`

Enables source map support, `postcss-loader` will use the previous source map given by other loaders and update it accordingly, if no previous loader is applied before `postcss-loader`, the loader will generate a source map for you.

**`webpack.config.js`**
```js
{
  test: /\.css/,
  use: [
    { loader: 'style-loader', options: { sourceMap: true } },
    { loader: 'css-loader', options: { sourceMap: true } },
    { loader: 'postcss-loader', options: { sourceMap: true } },
    { loader: 'sass-loader', options: { sourceMap: true } }
  ]
}
```

#### `'inline'`

You can set the `sourceMap: 'inline'` option to inline the source map
within the CSS directly as an annotation comment.

**`webpack.config.js`**
```js
{
  loader: 'postcss-loader',
  options: {
    sourceMap: 'inline'
  }
}
```

```css
.class { color: red; }

/*# sourceMappingURL=data:application/json;base64, ... */
```

<h2 align="center">Examples</h2>

### `Stylelint`

**`webpack.config.js`**
```js
{
  test: /\.css$/,
  use: [
    'style-loader',
    'css-loader',
    {
      loader: 'postcss-loader',
      options: {
        ident: 'postcss',
        plugins: [
          require('postcss-import')(),
          require('stylelint')(),
          ...,
        ]
      }
    }
  ]
}
```

### `Autoprefixing`

**`webpack.config.js`**
```js
{
  test: /\.css$/,
  use: [
    'style-loader',
    'css-loader',
    {
      loader: 'postcss-loader',
      options: {
        ident: 'postcss',
        plugins: [
          require('autoprefixer')({...options}),
          ...,
        ]
      }
    }
  ]
}
```

> :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.

### `CSS Modules`

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.

**`webpack.config.js`**
```js
{
  test: /\.css$/,
  use: [
    'style-loader',
    { loader: 'css-loader', options: { modules: true, importLoaders: 1 } },
    'postcss-loader'
  ]
}
```

or use [postcss-modules] instead of `css-loader`.

[`importLoaders`]: https://github.com/webpack-contrib/css-loader#importloaders
[cannot be used]: https://github.com/webpack/css-loader/issues/137
[CSS Modules]: https://github.com/webpack/css-loader#css-modules
[postcss-modules]: https://github.com/css-modules/postcss-modules

### `CSS-in-JS`

If you want to process styles written in JavaScript, use the [postcss-js] parser.

[postcss-js]: https://github.com/postcss/postcss-js

**`webpack.config.js`**
```js
{
  test: /\.style.js$/,
  use: [
    'style-loader',
    { loader: 'css-loader', options: { importLoaders: 2 } },
    { loader: 'postcss-loader', options: { parser: 'postcss-js' } },
    '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

[babel-plugin-add-module-exports]: https://github.com/59naga/babel-plugin-add-module-exports

### [Extract CSS][ExtractPlugin]

[ExtractPlugin]: https://github.com/webpack-contrib/mini-css-extract-plugin

**`webpack.config.js`**
```js
const devMode = process.env.NODE_ENV !== 'production'

const MiniCssExtractPlugin = require('mini-css-extract-plugin')

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          devMode ? 'style-loader' : MiniCssExtractPlugin.loader,
          'css-loader',
          'postcss-loader'
        ]
      }
    ]
  },
  plugins: [
    new MiniCssExtractPlugin({
      filename: devMode ? '[name].css' : '[name].[hash].css'
    })
  ]
}
```

<h2 align="center">Maintainers</h2>

<table>
  <tbody>
    <tr>
      <td align="center">
        <a href="https://github.com/michael-ciniawsky">
          <img width="150" height="150" src="https://github.com/michael-ciniawsky.png?v=3&s=150">
          </br>
          Michael Ciniawsky
        </a>
      </td>
      <td align="center">
        <a href="https://github.com/evilebottnawi">
          <img width="150" height="150" src="https://github.com/evilebottnawi.png?v=3&s=150">
          </br>
          Alexander Krasnoyarov
        </a>
      </td>
    </tr>
  <tbody>
</table>


[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/postcss/postcss-loader.svg
[deps-url]: https://david-dm.org/postcss/postcss-loader

[tests]: https://img.shields.io/travis/postcss/postcss-loader.svg
[tests-url]: https://travis-ci.org/postcss/postcss-loader

[cover]: https://coveralls.io/repos/github/postcss/postcss-loader/badge.svg
[cover-url]: https://coveralls.io/github/postcss/postcss-loader

[chat]: https://badges.gitter.im/postcss/postcss.svg
[chat-url]: https://gitter.im/postcss/postcss