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://cdnjs.cloudflare.com/ajax/libs/masonry/3.3.0/masonry.pkgd.min.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

var Grid = React.createClass({
    displayName: 'Grid',

    getInitialState: function(){
        return {
            masonry: null
        }
    },

    // Wrapper to layout child elements passed in
    render: function () {
        var children = this.props.children;
        return (
            <div className="grid">
                {children}
            </div>
        );
    },

    // When the DOM is rendered, let Masonry know what's changed
    componentDidUpdate: function() {
        if(this.state.masonry) {
            this.state.masonry.reloadItems();
            this.state.masonry.layout();
        }
    },

    // Set up Masonry
    componentDidMount: function() {
        var container = this.getDOMNode();
        if(!this.state.masonry) {
            this.setState({
                masonry: new Masonry( container )
            });
        } else {
            this.state.masonry.reloadItems();
        }
    }
});

React.render(
    <Grid>
        <img src="https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcSZF-_W81nofcLJqITxMru4VFTZARnRvTwoW4v0TPh77gkIh0MP"/>
        <img src="https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQpDiTs64ktB-AKegnd1lDryZXkXmtGBnvM-A1E4dReDwzwDUpk"/>
    </Grid>
, document.getElementById('container'));