Classy makes styling React components composable, extensible, and simple.

  • By Inturn
  • Last update: Jan 1, 2023
  • Comments: 0

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Table of Contents


npm install react-classy

Getting Started

Classy makes styling React components composable, extensible, and simple. Implementation requires only 3 steps:

  1. Import react-classy into your React component module
  2. Decorate your React component class with @Classy.
  3. Assign a CSS string to a static style prop on your React component class.

The styles defined on your React component will get automatically injected into the DOM right before your component mounts. Check out some examples of basic and advanced usage in the next section.



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import React, { Component } from 'react';
// Import Classy
import Classy from 'react-classy';

// Decorate your component
export default class Button extends Component {
  // Add your CSS styles
  static style = `
    .button {
      background: blue;
  render() {
    return (
      <button className="button">


Classy is also highly customizable and supports asynchronous style rendering, custom middleware, and theming! In the next example, we'll demonstrate all of the aforementioned while creating a button that switches themes when clicked.

import React, { Component } from 'react';
// Import the decorator and utils modules
import Classy, { Utils } from 'react-classy';
// CSS pre-processor
import stylus from 'stylus';


  // Makes Classy play nice with react-hot-loader :)
  hot: true,

  // Logs component css to console
  debug: true,

  // Will access specified prop to load component styles
  // instead of default `style` prop
  styleProp: 'stylus'

export default class ToggleButton extends Component {

  render() {
    return <button {...this.props} />;

  static defaultProps = {
    className: 'toggle-button toggle-button--default',
    children: 'Touch Me!',

    // Method that switches the component's theme.
    // Will toggle from 'light' to 'dark' and vice versa.
    onClick: function switchTheme(e) {
      let { name } = ToggleButton;
      let theme = Utils.getTheme(name);
      theme = 'dark' === theme ? 'light' : 'dark';
      Utils.setTheme(name, theme);


  // Let's define our themes as a static.
  // This makes it easy for others to modify a component's theme(s)
  // via class extension.
  static theme = {
    light: {
      textColor: '#a24bcf',
      background: 'transparent',
      borderRadius: '30px'
    dark: {
      textColor: '#fff',
      background: '#4b79cf',
      borderRadius: '4px'

  // Instead of a hard-coding your CSS,
  // you can assign a method that returns Promise that fulfills a CSS string.
  // Our default theme is set via rest param.
  static stylus(theme=ToggleButton.theme.light) {
    let styl = `


        color: convert($theme.textColor)
        background: convert($theme.background)
        border: 1px solid convert($theme.textColor)
        border-radius: convert($theme.borderRadius)
        outline: none
        padding: 20px
        font-size: 18px
        font-family: 'Helvetica Neue', helvetica, sans-serif
        transition: transform .3s ease

          cursor: pointer

          transform: translateY(4px)

    // Finally, let's use our Stylus middleware to render actual CSS
    // and return it with a Promise
    return new Promise((yep, nope) => stylus(styl.trim())
      .define('$theme', theme, true)
      .render((err, css) => err ? nope(err) : yep(css))


Decorator options and utility methods are comprehensively documented in the next section.




A class decorator will automatically inject styles into the DOM before your ReactComponent instance mounts.


// ES2016
export default class MyComponent extends React.Component { ... }

// ES2015
class MyComponent extends React.Component { ... }
export default Classy(MyComponent);

// ES5
var MyComponent = React.createClass({ ... });
module.exports = Classy(MyComponent);

Type: Object

Default: see below

An object that allows you to customize your Classy component settings. All settings are optional. See defaults below.


Type: Boolean

Default: false

Logs rendered cssText to debug console whens component styles are updated

Type: Boolean

Default: false

Applies two effects:

  • Replaces internal ref to the component if it gets hot-loaded
  • Component never uses cached cssText

Type: String

Default: style

Component prop to access for getting styles


Type: String

Default: themes

Component prop to access for getting themes


Type: String

Default: .name

Key under which Classy identifies your component. If not specified, your ReactComponent's will be used.


Type: String

Default: alias + '_' + Utils.genHash()

Example: MyButton_fxhhf

ID prop for component