React Base Fiddle (JSX)

Starting point for creating JSFiddles with React.

HTML

<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<div id="container">
    <!-- This element's contents will be replaced with your component. -->
</div>

CSS

.someclass {
  border: 5px solid black;
}

Babel + JSX

class Hello extends React.Component {
  constructor(props) {
    super(props);
    this.state = { style: {} };
    this.bloodyMary = this.bloodyMary.bind(this);
  }
  
  bloodyMary() {
    this.setState({
      style: { backgroundColor: 'red' },
      class: 'someclass'
    });
  }
  
  render() {
    return <div style={this.state.style} className={this.state.class}>
      <a onClick={this.bloodyMary}>Bloody Mary</a>
    </div>;
  }
}

ReactDOM.render(<Hello/>, document.getElementById('container'));