Also known as ECMAScript 6 (or ES6). Here's a handy guide describing most of the new features:

https://github.com/lukehoban/es6features#readme

Nice to see some ECMAScript love here! Having my entire codebase (client and server) in one language is beautiful, because I can use the same libraries on both sides. I'm looking forward to the new features in ES6, some of which are already supported by browsers. I've been using Typescript in the meantime to bridge some of the gaps.