<div id="main"></div>

// App
var App = React.createClass({
render: function() {
 return (
   <div>
     <Nav />
     <Header />
   </div>
  )
 }
});
 
// Nav
var Nav = React.createClass({
 render: function() {
   return (
    <ul className="nav nav-pills">
      <li role="presentation" className="active"><a href="#">Home</a></li>
      <li role="presentation"><a href="#">Profile</a></li>
      <li role="presentation"><a href="#">Messages</a></li>
    </ul>
  )
 }
});
 
// Header
var Header = React.createClass({
 render: function() {
   return (
     <h1 className="foo">Hello, world!</h1>
   )
 }
});
 
React.render(<App/>, document.querySelector("#main"));