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

.signal {
    padding: 10px;
    color: #fff;
    background-color: #000;
}

.signal-transition-appear {
    opacity: 0;
}

.signal-transition-appear-active {
    opacity: 1;
    transition: .5s;
}

.signal-transition-leave-active {
    opacity: 0;
    transition: .5s;
}

JavaScript 1.7

var ReactCSSTransitionGroup = React.addons.CSSTransitionGroup;

var SignalContent = React.createClass({
    render: function() {
        return (
            <div className='signal'>
                <p className='signal-message'>{this.props.message}</p>
                <button onClick={this.props.onClose} aria-label='Close'><span className='material-icons'>close</span></button>
            </div>
        );
    }
});

var Signal = React.createClass({
    handleClose: function() {
        this.setState({active: false})
        // this.props.onClose();
    },
    getInitialState: function() {
        return {
            active: true
        };
    },
    render: function() {
        return (
            <ReactCSSTransitionGroup transitionName='signal-transition' transitionAppear={true} component='div'>
                {this.state.active ? <SignalContent message={this.props.message} onClose={this.handleClose} /> : ''}
            </ReactCSSTransitionGroup>
        );
    }
});

var container = document.getElementById('container');
function handleClose() {
	React.unmountComponentAtNode(container);
}
 
React.render(<Signal message='test message' onClose={handleClose} />, container);