Iterates over iterable objects (including arrays, array-like objects, iterators and generators), invoking a custom iteration hook with statements to be executed for the value of each distinct property.
Docs: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of http://updates.html5rocks.com/2014/08/Collecting-and-Iterating-the-ES6-Way
Samples: https://github.com/GoogleChrome/samples/tree/gh-pages/collections-iterators-es6