What is postcss?
PostCSS is a tool for transforming CSS with JavaScript plugins. These plugins can lint your CSS, support variables and mixins, transpile future CSS syntax, inline images, and more.
What are postcss's main functionalities?
Autoprefixing
Automatically adds vendor prefixes to CSS rules using values from Can I Use. It is recommended by Google and used in Twitter and Alibaba.
postcss([ require('autoprefixer') ]).process(css).then(result => { result.warnings().forEach(warn => { console.warn(warn.toString()); }); console.log(result.css); });
CSS Variables
Transforms CSS Custom Properties (CSS variables) syntax into a static representation that can be understood by browsers that do not support this feature.
postcss([ require('postcss-custom-properties') ]).process(css).then(result => { console.log(result.css); });
CSS Nesting
Allows you to nest one style rule inside another, following the CSS Nesting Module Level 3 specification.
postcss([ require('postcss-nesting') ]).process(css).then(result => { console.log(result.css); });
Minification
A modular minifier, built on top of the PostCSS ecosystem. It is used to minimize CSS for better performance.
postcss([ require('cssnano') ]).process(css).then(result => { console.log(result.css); });
Future CSS Syntax
Allows you to use future CSS features today. It polyfills CSS features that are not yet fully supported in browsers.
postcss([ require('postcss-preset-env') ]).process(css).then(result => { console.log(result.css); });
Other packages similar to postcss
sass
Sass is a mature, stable, and powerful professional grade CSS extension language. It provides mechanisms such as variables, nesting, and mixins, which are not present in standard CSS. Unlike PostCSS, which uses JavaScript plugins, Sass has its own syntax and compiles to standard CSS.
less
Less is a backward-compatible language extension for CSS. It also allows variables, mixins, functions and many other techniques that allow you to make CSS more maintainable and extendable. Less is similar to Sass and differs from PostCSS in that it offers a different syntax and set of features.
stylus
Stylus is a preprocessor that serves as a more robust and feature-rich alternative to CSS. It supports both an indented syntax and regular CSS style. Stylus provides significant flexibility and feature parity with Sass and Less but with a different syntax and feature set compared to PostCSS.
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 PostCSS plugin is one of the most popular
CSS processors.
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 insert vendor prefixes.
Support / Discussion: Gitter
Twitter account: @postcss
VK.com page: postcss
中文翻译: README-cn.md
For PostCSS commercial support (consulting, improving the front-end culture
of your company, PostCSS plugins), contact Evil Martians
at surrender@evilmartians.com.
Plugins
Currently, PostCSS has more than 200 plugins. You can find all of the plugins
in the plugins list or in the searchable catalog. 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
postcss-use
allows you to explicitly set PostCSS plugins within CSS
and execute them only for the current file.postcss-modules
and react-css-modules
automatically isolate
selectors within components.postcss-autoreset
is an alternative to using a global reset
that is better for isolatable components.postcss-initial
adds all: initial
support, which resets
all inherited styles.cq-prolyfill
adds container query support, allowing styles that respond
to the width of the parent.
Use Future CSS, Today
Better CSS Readability
precss
contains plugins for Sass-like features, like variables, nesting,
and mixins.postcss-sorting
sorts the content of rules and at-rules.postcss-utilities
includes the most commonly used shortcuts and helpers.short
adds and extends numerous shorthand properties.
Images and Fonts
Linters
stylelint
is a modular stylesheet linter.stylefmt
is a tool that automatically formats CSS
according stylelint
rules.doiuse
lints CSS for browser support, using data from Can I Use.colorguard
helps you maintain a consistent color palette.
Other
postcss-rtl
combines both-directional (left-to-right and right-to-left) styles in one CSS file.cssnano
is a modular CSS minifier.lost
is a feature-rich calc()
grid system.rtlcss
mirrors styles for right-to-left locales.
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.
sugarss
is a indent-based syntax like Sass or Stylus.postcss-syntax
switch syntax automatically by file extensions.postcss-html
parsing styles in <style>
tags of HTML-like files.postcss-markdown
parsing styles in code blocks of Markdown files.postcss-jsx
parsing CSS in template / object literals of source files.postcss-styled
parsing CSS in template literals of source files.postcss-scss
allows you to work with SCSS
(but does not compile SCSS to CSS).postcss-sass
allows you to work with Sass
(but does not compile Sass to CSS).postcss-less
allows you to work with Less
(but does not compile LESS to CSS).postcss-less-engine
allows you to work with Less
(and DOES compile LESS to CSS using true Less.js evaluation).postcss-js
allows you to write styles in JS or transform
React Inline Styles, Radium or JSS.postcss-safe-parser
finds and fixes CSS syntax errors.midas
converts a CSS string to highlighted HTML.
Articles
More articles and videos you can find on awesome-postcss list.
Books
Usage
You can start using PostCSS in just two steps:
- Find and add PostCSS extensions for your build tool.
- Select plugins and add them to your PostCSS process.
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
:
module.exports = {
plugins: [
require('precss'),
require('autoprefixer')
]
}
Gulp
Use gulp-postcss
and gulp-sourcemaps
.
gulp.task('css', function () {
var postcss = require('gulp-postcss');
var sourcemaps = require('gulp-sourcemaps');
return gulp.src('src/**/*.css')
.pipe( sourcemaps.init() )
.pipe( postcss([ require('precss'), require('autoprefixer') ]) )
.pipe( sourcemaps.write('.') )
.pipe( gulp.dest('build/') );
});
npm run / CLI
To use PostCSS from your command-line interface or with npm scripts
there is postcss-cli
.
postcss --use autoprefixer -c options.json -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.
var postcss = require('postcss-js');
var prefixer = postcss.sync([ require('autoprefixer') ]);
prefixer({ display: 'flex' });
Runners
JS API
For other environments, you can use the JS API:
const fs = require('fs');
const postcss = require('postcss');
const precss = require('precss');
const autoprefixer = require('autoprefixer');
fs.readFile('src/app.css', (err, css) => {
postcss([precss, autoprefixer])
.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, () => 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:
- An array of plugins.
- An object of options.
Common options:
syntax
: an object providing a syntax parser and a stringifier.parser
: a special syntax parser (for example, SCSS).stringifier
: a special syntax output generator (for example, Midas).map
: source map options.from
: the input file name (most runners set it automatically).to
: the output file name (most runners set it automatically).
Editors & IDE Integration
Atom
Sublime Text
Vim
WebStorm
WebStorm 2016.3 has built-in PostCSS support.