Edit in JSFiddle

let user = { name: 'Tercel'};

const Hello = props => <div>Hello {props.name}.</div>;

const render = () =>
  ReactDOM.render(<Hello name={user.name} />,
    document.getElementById('hello'));

render();

<script src="https://facebook.github.io/react/js/jsfiddle-integration-babel.js"></script>

<div id="hello">
</div>