<div id="root"></div>
<script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.26.0/babel.js"></script>
<script type="text/babel">
class Greeting extends React.Component {
    render() {
        return (<p>Hello world</p>);
    }
}
ReactDOM.render(
    <Greeting />,
    document.getElementById('root')
);
</script>