Typed arrays, weak Maps, weak Sets, and let/const.

Now what I really wish to see in JavaScript are real Immutable Objects. Like, any variable declared with const makes that Object Immutable, not just preventing it from being reassigned. That, imo, would take JS to the next level. That and something like TypeScript/flow built in to native JS. It's do-able, and I see it happening way down the line, maybe es8/9 haha....