Looking at the React documentation (at the time of writing), the first example we find shows us how to define components using React.createClass.

Let's start with a very simple snippet:

  const Button = React.createClass({ 
    render() { 
      return <button />;
    } 
  });

With the preceding code, we created a button, and we can reference it inside other components in our application.

We can change the snippet to use plain JavaScript as follows:

  const Button = React.createClass({ 
    render() { 
      return React.createElement('button');
    } 
  });

We can run the code everywhere without needing to use Babel for transpiling, which is a good way to start with React, avoiding the effort of learning different tools in the React ecosystem.