use pure function instead of creating class

j/jsx.js

@@ -1,12 +1,8 @@
 var React = require('react');
 
-var HelloWorld = React.createClass({
-    displayName: 'HelloWorld',
-    render: function() {
-        return (
-            <span>Hello World</span>
-        );
-    }
-});
+var HelloWorld = function() {
+    return <span>Hello World</span>;
+};
+HelloWorld.displayName = 'HelloWorld';
 
 console.log(React.renderToString(<HelloWorld />));