Times are exciting in internet land! ECMAScript2015 (aka ES6) has been approved, so the final specs are available for anyone to peruse. Read more about new features in a Treehouse blog post here or start fiddling around in your browser with some examples here or here.
Brendan Eich announced WebAssembly, and Axel Rauschmayer has a very readable blog post explaining it as well. In summary, the major browser players are all on board to help make a subset of JavaScript that compiles more quickly. This will be useful when performance is critical. Another bonus is JavaScript will load more quickly. Further, WebAssembly will make it easier to compile other languages for use in the web.
David Rabkin 