React Base Fiddle (JSX)

Starting point for creating JSFiddles with React. This uses React with Addons.

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>

CSS

span div {
    display:inline-block; 
    background: black; color: white; padding: 30px; font-size: 24px;
}

.example-enter {
  opacity: 0.01;
  transition: opacity 1.5s ease-in;
}

.example-enter.example-enter-active {
  opacity: 1;
}

.example-leave {
  opacity: 1;
  transition: opacity 1.5s ease-in;
}

.example-leave.example-leave-active {
  opacity: 0.01;
}

JavaScript 1.7

var ReactCSSTransitionGroup = React.addons.CSSTransitionGroup;
var Hello = React.createClass({
    getInitialState: function() {
      return {on: true};
    },
    onClick: function() {
      this.setState({on: !this.state.on});
    },
    render: function() {
        var k = this.state.on ? (<div> Hello {this.props.name} </div>) : "";
        return <div>
            <a href="#" onClick={this.onClick}> Click to toggle </a> <br/> <br/>
            <ReactCSSTransitionGroup transitionName="example">
              {k}
            </ReactCSSTransitionGroup>
          </div>;
    }
});
 
React.render(<Hello name="World" />, document.getElementById('container'));