Frequently Asked Questions

How do I use pseudo-selectors like :checked, :last, :before, or :after?

Radium only provides the interactivity pseudo-selectors :hover, :active, and :focus. You need to use JavaScript logic to implement the others. To implement :checked for example:

class CheckForBold extends React.Component {
  constructor() {
    this.state = {isChecked: false};

  _onChange = () => {
    this.setState({isChecked: !this.state.isChecked});

  render() {
    return (
      <label style={{fontWeight: this.state.isChecked ? 'bold' : 'normal'}}>
      {' '}Check for bold

Instead of :first and :last, change behavior during array iteration. Note that the border property is broken down into parts to avoid complications as in issue #95.

var droids = [
  'Probe Droid'

class DroidList extends React.Component {
  render() {
    return (
      <ul style={{padding: 0}}>
        {, index, arr) =>
          <li key={index} style={{
            borderColor: 'black',
            borderRadius: index === 0 ? '12px 12px 0 0' :
              index === (arr.length - 1) ? '0 0 12px 12px' : '',
            borderStyle: 'solid',
            borderWidth: index === (arr.length - 1) ? '1px' : '1px 1px 0 1px',
            cursor: 'pointer',
            listStyle: 'none',
            padding: 12,
            ':hover': {
              background: '#eee'

DroidList = Radium(DroidList);

Instead of :before and :after, add extra elements when rendering your HTML.

How can I use ReactCSSTransitionGroup without any classes?

Try out the experimental ReactStyleTransitionGroup instead.

How can I use Radium with jsbin?

To get the latest version, drop this into the HTML:

<script src=""></script>

We also recommend changing the JavaScript language to ES6/Babel.

Can I use my favourite CSS/LESS/SASS syntax?

Yes, with the help of the react-styling module, which requires template strings. Using react-styling you can write your styles in any syntax you like (curly braces or tabs, CSS, LESS/SASS, anything will do).

The example from the main Readme (using regular CSS syntax)

<Button kind="primary">Radium Button</Button>
import styler from 'react-styling/flat'

class Button extends React.Component {
  static propTypes = {
    kind: PropTypes.oneOf(['primary', 'warning']).isRequired

  render() {
    return (
      <button style={style[`button_${this.props.kind}`]}>

Button = Radium(Button);

const style = styler`
  .button {
    color: #fff;

    :hover {
      background: ${color('#0074d9').lighten(0.2).hexString()};

    &.primary {
      background: #0074D9;

    &.warning {
      background: #FF4136;

You can find a more advanced example in the react-styling readme.

Can I use Radium with Bootstrap?

See issue #323 for discussion.

Radium doesn't mess with the style prop of non-DOM elements. This includes thin wrappers like react-router's Link component. We can't assume that a custom component will use style the same way DOM elements do. For instance, it could be a string enum to select a specific style. In order for resolving style on a custom element to work, that element needs to actually pass that style prop to the DOM element underneath, in addition to passing down all the event handlers (onMouseEnter, etc). Since Radium has no control over the implementation of other components, resolving styles on them is not safe.

A workaround is to wrap your custom component in Radium, even if you do not have the source, like this:

var Link = require('react-router').Link;
Link = Radium(Link);

Huge thanks to @mairh for coming up with this idea in issue #324.

We are also exploring adding a mechanism to bypass Radium's check, see issue #258.

How can I get rid of userAgent warnings in tests?

You might see warnings like this when testing React components that use Radium:

Radium: userAgent should be supplied for server-side rendering. See
/docs/api#radium for more information.
Either the global navigator was undefined or an invalid userAgent was provided. Using a valid userAgent? Please let us k
now and create an issue at

This isn't an issue if you run your tests in a browser-like environment such as jsdom or PhantomJS, but if you just run them in Node, there will be no userAgent defined. In your test setup, you can define one:

global.navigator = {userAgent: 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2454.85 Safari/537.36'};

Make sure it is a real user agent that inline-style-prefixer recognizes, or you'll still get the second error. The above UA is Chrome 49 from the inline-style-prefixer tests.

Why do React warnings have the wrong component name?

You may see the name "Constructor" instead of your component name, for example: "Warning: Failed propType: Invalid prop onClick of type function supplied to Constructor, expected string." or "Warning: Each child in an array or iterator should have a unique "key" prop. Check the render method of Constructor."

Your transpiler is probably not able to set the displayName property of the component correctly, which can happen if you wrap React.createClass immediately with Radium, e.g. var Button = Radium(React.createClass({ ... }));. Instead, wrap your component afterward, ex. Button = Radium(Button);, or when exporting, ex. export default Radium(Button);, or set displayName manually.

Why does the browser state of a child element not reset after unmounting and remounting?

If you have an element that takes a browser state (e.g. :active, :hover, :focus), you need to give it a unique key prop. There is a case where if you only have a single element in your component that takes an interactive style, you do not need to provide a key; however, if you remove the element and show it again, it will maintain it's state, which is usually unexpected behavior. To fix this, simply give it a custom key prop.