React, a JavaScript library for building user interfaces
<p><pre><code>    var HelloMessage = React.createClass({
      render: function() {
        return <div>{'Hello ' + this.props.name}</div>;
      }
    });
</code></pre>
Wait, what's going on here, how come the return string isn't wrapped in quotes?<p>EDIT: Oh I see it's something called "JSX." Interesting.