postcss-js

What is postcss-js?

The postcss-js package allows you to use PostCSS, a tool for transforming CSS with JavaScript, in a JavaScript environment. This enables the processing of CSS styles with JavaScript objects, facilitating dynamic style generation and manipulation within JavaScript projects.

What are postcss-js's main functionalities?

Parsing CSS to JS Objects

This feature allows the conversion of CSS styles into JavaScript objects, making it easier to manipulate CSS properties and values programmatically.

const postcssJs = require('postcss-js');
const autoprefixer = require('autoprefixer');
const root = postcssJs.parse({ color: 'red' });
console.log(root);

Applying PostCSS Plugins

Enables the use of PostCSS plugins, such as autoprefixer, directly on JavaScript objects representing CSS styles, allowing for advanced CSS processing and manipulation.

const postcssJs = require('postcss-js');
const autoprefixer = require('autoprefixer');
const prefixer = postcssJs.sync([ autoprefixer ]); 
const prefixed = prefixer({ display: 'flex' });
console.log(prefixed);

Other packages similar to postcss-js

styled-components

Styled-components is a library for React and React Native that allows you to use component-level styles in your application. It uses tagged template literals to style your components. Unlike postcss-js, which focuses on transforming CSS with JavaScript, styled-components aim to enhance CSS for styling React component systems.

emotion

Emotion is a performant and flexible CSS-in-JS library that allows you to style applications quickly with string or object styles. It supports both the CSS and CSS-in-JS approaches, providing a more integrated styling solution for React applications compared to postcss-js, which is more focused on CSS transformation and manipulation.

tailwindcss

Tailwind CSS is a utility-first CSS framework for rapidly building custom designs. Unlike postcss-js, which is a tool for transforming CSS with JavaScript, Tailwind provides a set of utility classes to build custom designs directly in your markup, promoting a different approach to styling web applications.

README

PostCSS JS

PostCSS for React Inline Styles, Radium, JSS and other CSS-in-JS.

For example, to use Stylelint, RTLCSS or postcss-write-svg plugins in your workflow.

Usage

Processing

let prefixer = postcssJs.sync([ autoprefixer ]);

let style = prefixer({
    display: 'flex'
});

style //=> { display: ['-webkit-box', '-webkit-flex', '-ms-flexbox', 'flex'] }

Compile CSS-in-JS to CSS

let 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

let css  = '@media screen { z-index: 1 }'
let root = postcss.parse(css);

postcssJs.objectify(root) //=> { '@media screen': { zIndex: '1' } }

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"
    }
]

Changelog

1.0.1

• Ignore nodes with undefined value.

1.0

• Use PostCSS 6.0.

0.3

• Add support for at-rules with same name (like @font-face).

0.2

• Add !important support (by Dan Lynch).