A lib for generating CSS from JavaScript.
JavaScript HTML
Latest commit c37714a Jan 21, 2017 @kof kof add react style guide



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JSS is a better abstraction over CSS. It uses JavaScript as a language to describe styles in a declarative and maintainable way. It is a high performance JS to CSS compiler which works at runtime and server-side. You can use it with React or with any other library. It is about 5KB (minfied and gzipped) and is extensible via plugins API.

Libraries on top of JSS

  • React-JSS integration for React.
  • Theme Reactor Experimental React integration with theming.
  • Aphrodisiac provides Aphrodite like api on top of JSS.
  • Aesthetic A React style abstraction layer with theme support.


  1. Live examples.
  2. Benefits
  3. Setup
  4. JSON API (JSS Syntax)
  5. JavaScript API
  6. Server-side rendering
  7. Performance
  8. Plugins API
  9. Official plugins
  10. External projects
  11. CLI Converter
  12. Contributing


You need to setup plugins before. You can use a preset for a quick setup with default plugins.

import jss from 'jss'
import preset from 'jss-preset-default'
import color from 'color'

// One time setup with default plugins and settings.

const styles = {
  button: {
    fontSize: 12,
    '&:hover': {
      background: 'blue'
  ctaButton: {
    extend: 'button',
    '&:hover': {
      background: color('blue').darken(0.3).hexString()
  '@media (min-width: 1024px)': {
    button: {
      width: 200

const {classes} = jss.createStyleSheet(styles).attach()

document.body.innerHTML = `
  <button class="${classes.button}">Button</button>
  <button class="${classes.ctaButton}">CTA Button</button>


  <style type="text/css">
    .button-123456 {
      font-size: 12px;
    .button-123456:hover {
      background: blue;
    .ctaButton-789012 {
      font-size: 12px;
    .ctaButton-789012:hover {
      background: red;
    @media (min-width: 1024px) {
      .button-123456 {
        min-width: 200px;
  <button class="button-123456">Button</button>
  <button class="ctaButton-789012">CTA Button</button>

When should I use it?

  • You build a JavaScript heavy application.
  • You use components based architecture.
  • You build a reusable UI library.
  • You need a collision free CSS (external content, third-party UI components ...).
  • You need code sharing between js and css.
  • Minimal download size is important to you.
  • Robustness and code reuse is important to you.
  • Ease of maintenance is important to you.
  • You just want to use any of its benefits


  • Make it easier for newcomers to setup jss with plugins (like presets).
  • Make JSON DSL even better, for e.g. jss-expand.
  • Make it easy to see when changes in the core break plugins (integrate plugins test suite).
  • Make community create plugins (better plugins API documentation, infrastructure).
  • Do more benchmarking, include plugins, always track perf regressions.
  • Introduce a way for theming with react-jss or replace it by jss-theme-reactor
  • Make SSR even better (vendor prefixer, smaller critical CSS)
  • Make CLI tool better, allow integration of styles written in various preprocessing languages as well as pure css.
  • React Native support.
  • Add converters stylus, sass and co. to cli with constants reuse.

Browsers Support

We have automated tests running in real browsers.




Thanks to BrowserStack for providing the infrastructure that allows us to run our tests in real browsers and to all awesome contributors.