postcss/postcss-js

PostCSS JS

PostCSS for CSS-in-JS and styles in JS objects.

For example, to use Stylelint or RTLCSS plugins in your workflow.

---

  PostCSS JS Parser is built by Evil Martians, an American design and engineering consultancy for developer tools, AI, and cybersecurity startups.

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Usage

Processing

const postcssJs = require('postcss-js')
const autoprefixer = require('autoprefixer')

const prefixer = postcssJs.sync([autoprefixer])

const style = prefixer({
  userSelect: 'none'
})

style //=> {
//     WebkitUserSelect: 'none',
//        MozUserSelect: 'none',
//         msUserSelect: 'none',
//           userSelect: 'none'
//   }

Compile CSS-in-JS to CSS

const postcss = require('postcss')
const postcssJs = require('postcss-js')

const style = {
  'top': 10,
  '&:hover': {
    top: 5
  }
}

postcss()
  .process(style, { parser: postcssJs })
  .then(result => {
    result.css //=> top: 10px;
    //   &:hover { top: 5px; }
  })

Compile CSS to CSS-in-JS

const postcss = require('postcss')
const postcssJs = require('postcss-js')

const css =
  '--text-color: #DD3A0A; @media screen { z-index: 1; color: var(--text-color) }'
const root = postcss.parse(css)

postcssJs.objectify(root) //=> {
//     '--text-color': '#DD3A0A',
//     '@media screen': {
//       zIndex: '1',
//       color: 'var(--text-color)'
//     }
//   }

API

sync(plugins): function

Create PostCSS processor with simple API, but with only sync PostCSS plugins support.

Processor is just a function, which takes one style object and return other.

async(plugins): function

Same as sync, but also support async plugins.

Returned processor will return Promise.

parse(obj): Root

Parse CSS-in-JS style object to PostCSS Root instance.

It converts numbers to pixels and parses [Free Style] like selectors and at-rules:

{
    '@media screen': {
        '&:hover': {
            top: 10
        }
    }
}

This methods use Custom Syntax name convention, so you can use it like this:

postcss().process(obj, { parser: postcssJs })

objectify(root): object

Convert PostCSS Root instance to CSS-in-JS style object.

Troubleshoot

Webpack may need some extra config for some PostCSS plugins.

Module parse failed

Autoprefixer and some other plugins need a json-loader to import data.

So, please install this loader and add to webpack config:

loaders: [
  {
    test: /\.json$/,
    loader: 'json-loader'
  }
]