JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.2.0/react.min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.2.0/react-dom.min.js"></script>

  <body>
    <div id="app"></div>
  </body>

JavaScript

class Mine {
	constructor() {
		this.x = 123;
	}

	meth() {}
}

let MyElement = React.createClass({
	doIt: function() {
		let m = new Mine();
		this.setState(m, () => {
			console.log('1:', m instanceof Mine, m.x, m.meth);
			console.log('2:', this.state instanceof Mine, this.state.x, this.state.meth);
		});
	},
	render: function() { 
  	return React.createElement('button', {onClick: this.doIt}, 'do it'); 
  }
});

ReactDOM.render(
	React.createElement(MyElement),
	document.getElementById('app')
);