<main>
</main>

var HelloWorld = React.createClass({
  render() {
    return (<div className="hello-world">
        <p>Hello {1+1} World</p>
      </div>)    
  }
});

var App = React.createClass({
  render() {
    return (<div>
        <HelloWorld />
        <HelloWorld />
        <HelloWorld />
        <HelloWorld />
      </div>);
    
  }
});

ReactDOM.render(React.createElement(App), document.querySelector('main'));