JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://unpkg.com/react@next/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@next/umd/react-dom.development.js"></script>

JavaScript

class Foo extends React.Component {
	render() {
		return React.createElement('h1');
	}
}

class Bar extends React.Component {
  componentDidMount() {
    var container = document.createElement('div');
    var instance = ReactDOM.render(React.createElement(Foo), container);
    alert(instance)  
  }
  render() {
	  return null
  }
}

var container2 = document.createElement('div');
ReactDOM.render(React.createElement(Bar), container2)