React Hello World Example with ES6+JSX

A basic Hello World widget with in browser JSX transformed + ES6 support

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/0.13.1/JSXTransformer.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/0.13.1/react-with-addons.js"></script>
<script src="https://facebook.github.io/react/js/jsfiddle-integration.js"></script>
<div id="container">
    <!-- This element's contents will be replaced with your component. -->
</div>

JavaScript 1.7

class TextEntry extends React.Component {
  constructor() {
    super();
    this.state = {
      val: 0
    };
    this.onChange = this.onChange.bind(this);
  }

  onChange(event) {
    if (event.target.value === '') { event.target.value = 0; }
    let val = parseInt(event.target.value);
    if (!isNaN(val)) { this.setState({ val: val }); }
  };

  render() {
    return (
      <div>
        <input type="text" value={this.state.val} onChange={this.onChange} />
        <p>Weighted value: {this.state.val * 2}</p>
      </div>);
  }
}

React.render(<TextEntry />,
             document.getElementById('container'));