npm i -D postcss-load-config

npm i -S|-D postcss-plugin

Install all required PostCSS plugins and save them to your package.json dependencies/devDependencies

Then create a PostCSS config file by choosing one of the following formats

package.json

Create a postcss section in your project's package.json

Project (Root)
  |– client
  |– public
  |
  |- package.json

{
  "postcss": {
    "parser": "sugarss",
    "map": false,
    "plugins": {
      "postcss-plugin": {}
    }
  }
}

.postcssrc

Create a .postcssrc file in JSON or YAML format

ℹ️ It's recommended to use an extension (e.g .postcssrc.json or .postcssrc.yml) instead of .postcssrc

Project (Root)
  |– client
  |– public
  |
  |- (.postcssrc|.postcssrc.json|.postcssrc.yml)
  |- package.json

.postcssrc.json

{
  "parser": "sugarss",
  "map": false,
  "plugins": {
    "postcss-plugin": {}
  }
}

.postcssrc.yml

parser: sugarss
map: false
plugins:
  postcss-plugin: {}

[!NOTE] For YAML configs, you must have yaml installed as a peer dependency.

.postcssrc.js or postcss.config.js

You may need some logic within your config. In this case create JS/TS file named:

• .postcssrc.js
• .postcssrc.mjs
• .postcssrc.cjs
• .postcssrc.ts
• .postcssrc.mts
• .postcssrc.cts
• postcss.config.js
• postcss.config.mjs
• postcss.config.cjs
• postcss.config.ts
• postcss.config.mts
• postcss.config.cts

[!NOTE] For TypeScript configs, you must have tsx or jiti installed as a peer dependency.

Project (Root)
  |– client
  |– public
  |- (.postcssrc|postcss.config).(js|mjs|cjs|ts|mts|cts)
  |- package.json

You can export the config as an {Object}

.postcssrc.js

module.exports = {
  parser: 'sugarss',
  map: false,
  plugins: {
    'postcss-plugin': {}
  }
}

Or export a {Function} that returns the config (more about the ctx param below)

.postcssrc.js

module.exports = (ctx) => ({
  parser: ctx.parser ? 'sugarss' : false,
  map: ctx.env === 'development' ? ctx.map : false,
  plugins: {
    'postcss-plugin': ctx.options.plugin
  }
})

Plugins can be loaded either using an {Object} or an {Array}

{Object}

.postcssrc.js

module.exports = ({ env }) => ({
  ...options,
  plugins: {
    'postcss-plugin': env === 'production' ? {} : false
  }
})

ℹ️ When using an {Object}, the key can be a Node.js module name, a path to a JavaScript file that is relative to the directory of the PostCSS config file, or an absolute path to a JavaScript file.

{Array}

.postcssrc.js

module.exports = ({ env }) => ({
  ...options,
  plugins: [
    env === 'production' ? require('postcss-plugin')() : false
  ]
})

:warning: When using an {Array}, make sure to require() each plugin

|Name|Type|Default|Description| |:--:|:--:|:-----:|:----------| |to|{String}|undefined|Destination File Path| |map|{String\|Object}|false|Enable/Disable Source Maps| |from|{String}|undefined|Source File Path| |parser|{String\|Function}|false|Custom PostCSS Parser| |syntax|{String\|Function}|false|Custom PostCSS Syntax| |stringifier|{String\|Function}|false|Custom PostCSS Stringifier|

parser

.postcssrc.js

module.exports = {
  parser: 'sugarss'
}

syntax

.postcssrc.js

module.exports = {
  syntax: 'postcss-scss'
}

stringifier

.postcssrc.js

module.exports = {
  stringifier: 'midas'
}

map

.postcssrc.js

module.exports = {
  map: 'inline'
}

:warning: In most cases options.from && options.to are set by the third-party which integrates this package (CLI, gulp, webpack). It's unlikely one needs to set/use options.from && options.to within a config file. Unless you're a third-party plugin author using this module and its Node API directly dont't set options.from && options.to yourself

to

module.exports = {
  to: 'path/to/dest.css'
}

from

module.exports = {
  from: 'path/to/src.css'
}

{} || null

The plugin will be loaded with defaults

'postcss-plugin': {} || null

.postcssrc.js

module.exports = {
  plugins: {
    'postcss-plugin': {} || null
  }
}

:warning: {} must be an empty {Object} literal

{Object}

The plugin will be loaded with given options

'postcss-plugin': { option: '', option: '' }

.postcssrc.js

module.exports = {
  plugins: {
    'postcss-plugin': { option: '', option: '' }
  }
}

false

The plugin will not be loaded

'postcss-plugin': false

.postcssrc.js

module.exports = {
  plugins: {
    'postcss-plugin': false
  }
}

Ordering

Plugin execution order is determined by declaration in the plugins section (top-down)

{
  plugins: {
    'postcss-plugin': {}, // [0]
    'postcss-plugin': {}, // [1]
    'postcss-plugin': {}  // [2]
  }
}

When using a {Function} (postcss.config.js or .postcssrc.js), it's possible to pass context to postcss-load-config, which will be evaluated while loading your config. By default ctx.env (process.env.NODE_ENV) and ctx.cwd (process.cwd()) are available on the ctx {Object}

ℹ️ Most third-party integrations add additional properties to the ctx (e.g postcss-loader). Check the specific module's README for more information about what is available on the respective ctx

postcss.config.js

module.exports = (ctx) => ({
  parser: ctx.parser ? 'sugarss' : false,
  map: ctx.env === 'development' ? ctx.map : false,
  plugins: {
    'postcss-import': {},
    'postcss-nested': {},
    cssnano: ctx.env === 'production' ? {} : false
  }
})

"scripts": {
  "build": "NODE_ENV=production node postcss",
  "start": "NODE_ENV=development node postcss"
}

const { readFileSync } = require('fs')

const postcss = require('postcss')
const postcssrc = require('postcss-load-config')

const css = readFileSync('index.css', 'utf8')

const ctx = { parser: true, map: 'inline' }

postcssrc(ctx).then(({ plugins, options }) => {
  postcss(plugins)
    .process(css, options)
    .then((result) => console.log(result.css))
})

"scripts": {
  "build": "NODE_ENV=production gulp",
  "start": "NODE_ENV=development gulp"
}

const { task, src, dest, series, watch } = require('gulp')

const postcss = require('gulp-postcssrc')

const css = () => {
  src('src/*.css')
    .pipe(postcss())
    .pipe(dest('dest'))
})

task('watch', () => {
  watch(['src/*.css', 'postcss.config.js'], css)
})

task('default', series(css, 'watch'))

"scripts": {
  "build": "NODE_ENV=production webpack",
  "start": "NODE_ENV=development webpack-dev-server"
}

webpack.config.js

module.exports = (env) => ({
  module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          'style-loader',
          'css-loader',
          'postcss-loader'
        ]
      }
    ]
  }
})

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