React Base Fiddle (JSX)
Starting point for creating JSFiddles with React. This uses React with Addons.
HTML
<script src="https://cdnjs.cloudflare.com/ajax/libs/babel-core/5.8.24/browser.js"></script>
<script src="https://facebook.github.io/react/js/jsfiddle-integration-babel.js"></script>JavaScript 1.7
let a = x => x*2;
console.log(a(4));