postcss README

The project's README from github.com/postcss/postcss. As one markdown file: README.md.

PostCSS

Philosopher’s stone, logo of PostCSS

PostCSS is a tool for transforming styles with JS plugins. These plugins can lint your CSS, support variables and mixins, transpile future CSS syntax, inline images, and more.

PostCSS is used by industry leaders including Wikipedia, Twitter, Alibaba, and JetBrains. The Autoprefixer and Stylelint PostCSS plugins are some of the most popular CSS tools.

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

Sponsorship

PostCSS needs your support. We are accepting donations at Open Collective and GitHub Sponsors.


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Plugins

PostCSS takes a CSS file and provides an API to analyze and modify its rules (by transforming them into an Abstract Syntax Tree). This API can then be used by plugins to do a lot of useful things, e.g., to find errors automatically, or to insert vendor prefixes.

Currently, PostCSS has more than 200 plugins. You can find all of the plugins in the plugins list. Below is a list of our favorite plugins — the best demonstrations of what can be built on top of PostCSS.

If you have any new ideas, PostCSS plugin development is really easy.

Solve Global CSS Problem

Use Future CSS, Today

Better CSS Readability

Images and Fonts

Linters

Other

Syntaxes

PostCSS can transform styles in any syntax, not just CSS. If there is not yet support for your favorite syntax, you can write a parser and/or stringifier to extend PostCSS.

Articles

More articles and videos you can find on awesome-postcss list.

Books

Usage

You can start using PostCSS in just two steps:

  1. Find and add PostCSS extensions for your build tool.
  2. Select plugins and add them to your PostCSS process.

CSS-in-JS

The best way to use PostCSS with CSS-in-JS is astroturf. Add its loader to your webpack.config.js:

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        use: ['style-loader', 'postcss-loader']
      },
      {
        test: /\.jsx?$/,
        use: ['babel-loader', 'astroturf/loader']
      }
    ]
  }
}

Then create postcss.config.js:

/** @type {import('postcss-load-config').Config} */
const config = {
  plugins: [require('autoprefixer'), require('postcss-nested')]
}

module.exports = config

Parcel

Parcel has built-in PostCSS support. It already uses Autoprefixer and cssnano. If you want to change plugins, create postcss.config.js in project’s root:

/** @type {import('postcss-load-config').Config} */
const config = {
  plugins: [require('autoprefixer'), require('postcss-nested')]
}

module.exports = config

Parcel will even automatically install these plugins for you.

Please, be aware of the several issues in Version 1. Notice, Version 2 may resolve the issues via issue #2157.

Webpack

Use postcss-loader in webpack.config.js:

module.exports = {
  module: {
    rules: [
      {
        test: /\.css$/,
        exclude: /node_modules/,
        use: [
          {
            loader: 'style-loader'
          },
          {
            loader: 'css-loader',
            options: {
              importLoaders: 1
            }
          },
          {
            loader: 'postcss-loader'
          }
        ]
      }
    ]
  }
}

Then create postcss.config.js:

/** @type {import('postcss-load-config').Config} */
const config = {
  plugins: [require('autoprefixer'), require('postcss-nested')]
}

module.exports = config

Gulp

Use gulp-postcss and gulp-sourcemaps.

gulp.task('css', () => {
  const postcss = require('gulp-postcss')
  const sourcemaps = require('gulp-sourcemaps')

  return gulp
    .src('src/**/*.css')
    .pipe(sourcemaps.init())
    .pipe(postcss([require('autoprefixer'), require('postcss-nested')]))
    .pipe(sourcemaps.write('.'))
    .pipe(gulp.dest('build/'))
})

npm Scripts

To use PostCSS from your command-line interface or with npm scripts there is postcss-cli.

postcss --use autoprefixer -o main.css css/*.css

Browser

If you want to compile CSS string in browser (for instance, in live edit tools like CodePen), just use Browserify or webpack. They will pack PostCSS and plugins files into a single file.

To apply PostCSS plugins to React Inline Styles, JSS, Radium and other CSS-in-JS, you can use postcss-js and transforms style objects.

const postcss = require('postcss-js')
const prefixer = postcss.sync([require('autoprefixer')])

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

Runners

JS API

For other environments, you can use the JS API:

const autoprefixer = require('autoprefixer')
const postcss = require('postcss')
const postcssNested = require('postcss-nested')
const fs = require('fs')

fs.readFile('src/app.css', (err, css) => {
  postcss([autoprefixer, postcssNested])
    .process(css, { from: 'src/app.css', to: 'dest/app.css' })
    .then(result => {
      fs.writeFile('dest/app.css', result.css, () => true)
      if (result.map) {
        fs.writeFile('dest/app.css.map', result.map.toString(), () => true)
      }
    })
})

Read the PostCSS API documentation for more details about the JS API.

All PostCSS runners should pass PostCSS Runner Guidelines.

Options

Most PostCSS runners accept two parameters:

Common options:

Treat Warnings as Errors

In some situations it might be helpful to fail the build on any warning from PostCSS or one of its plugins. This guarantees that no warnings go unnoticed, and helps to avoid bugs. While there is no option to enable treating warnings as errors, it can easily be done by adding postcss-fail-on-warn plugin in the end of PostCSS plugins:

module.exports = {
  plugins: [require('autoprefixer'), require('postcss-fail-on-warn')]
}

Editors & IDE Integration

VS Code

Sublime Text

Vim

WebStorm

To get support for PostCSS in WebStorm and other JetBrains IDEs you need to install this plugin.

Security Contact

To report a security vulnerability, please use the Tidelift security contact. Tidelift will coordinate the fix and disclosure.

For Enterprise

Available as part of the Tidelift Subscription.

The maintainers of postcss and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.

postcss (postcss/postcss)

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29K ·GitHub
Postcss
What is this?PostCSS is a Node.js tool for transforming styles with JS plugins: it parses CSS into an Abstract Syntax Tree and gives plugins an API to analyze and modify its rules.
Is it a preprocessor like Sass, or something different?It is a framework rather than a ready-made preprocessor: PostCSS itself only parses and re-generates styles, while 200+ plugins do the actual work, and custom parsers let it handle almost any syntax.
How do I add it to my project?Two steps: add a PostCSS extension for your build tool (e.g. 'postcss-loader' for webpack), then create a postcss.config.js listing your chosen plugins.
Which build tools does it integrate with?Most bundlers and task runners: postcss-loader for webpack, gulp-postcss for Gulp, built-in support in Parcel, postcss-cli for npm scripts, runners for Grunt, Rollup, Svelte and others, plus a plain JS API.
Will it compile my SCSS or Less files to CSS?No: postcss-scss and postcss-sass let you work with the syntax but do not compile it to CSS; only postcss-less-engine actually compiles Less, using real Less.js evaluation.
Is it Node-only, or can it run in the browser too?It is a Node.js package (Node 10, 12 or 14+), but it can also run in the browser: bundle PostCSS and its plugins with Browserify or webpack, e.g. for live-edit tools like CodePen.
What can PostCSS plugins actually do?Almost anything a stylesheet needs: autoprefixer adds vendor prefixes from Can I Use data, postcss-preset-env enables future CSS today, stylelint lints, cssnano minifies, postcss-nested unwraps nested rules the Sass way.
Does it work with CSS-in-JS like styled-components?Yes: postcss-styled-syntax parses CSS in CSS-in-JS template literals, postcss-js transforms style objects for React Inline Styles, JSS or Radium, and the README recommends astroturf as the best way to combine the two.
How hard is it to write my own plugin?The README says plugin development is really easy: a plugin is just JS working with the parsed AST through PostCSS's API, and new plugin ideas are explicitly welcomed.
Will my editor understand PostCSS?Yes: there are VS Code extensions (plus an IntelliSense addon), a Sublime Text and a Vim syntax highlighter, and a plugin for WebStorm and other JetBrains IDEs.
What are similar projects?linaria, prettier, mdb-ui-kit, stylelint, stylex, unocss, selectize.js, vanilla-extract
Which topics is it in?postcss, less, css-in-js, ast, scss, sass, parser, webpack, css, plugin, web-development, framework
Creator
postcss
Size
11.1 MB
Stars
29K
Updated
CommitOct 12Release8.5.30Oct 12
Age
13y
Commits · 90 Days