react_tutorial3.jsx

// The simplest component is a Javascript function that takes `props`
// as an argument and returns a React element.  This is called a 
// "functional component" since, well, it's just a function!
function CommentBox(props) {
  return <div>Hello, here is a comment: {props.content} </div>;
}

// If you're using ES 6, React components can be created 
// by extending React.Component.
class CommentBox extends React.Component {
  render() {
    return (
      // Note this <div> is not a DOM node, but an instance of a React div element
      <div className="commentBox">
        Hello, here is a comment: {props.content} 
      </div>
    )
  }
}

// You can render components
ReactDom.render(
  <CommentBox content="My opinion matters!"/>,
  document.getElementId("root")
);