JavaScript React - Linking React File

Linking React File

Importing "react.min.js" using a script tag will mean the "React" object is a global variable.
Importing "react-dom.min.js" using a script tag will mean the "ReactDOM" object is a global variable.
Notice that the script reference to "index.js" is at the bottom of the body.
The JavaScript code does not contain any JSX.

index.html

<!DOCTYPE html> 
<html> 
<head> 
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script> 
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script> 
</head> 

<body> 
<div id="app"></div> 
<script src="index.js" type="text/javascript"></script> 
</body> 
</html>

index.js

var App = React.createClass({ 
  displayName: 'App',  
  render: function() { 
    // The second parameter is an object of attributes for the element (if any) 
    return React.createElement('div', { }, 'Hello World');  
  } 
}); 
 
ReactDOM.render( 
  React.createElement(App), 
  document.getElementById('app')  
);