FWIW, Haxe is a solid alternative if you're looking into alt-js or cross platform (mobile) development: http://haxe.org/

It doesn't have the money of Google, but it has been around for 8 years, and is backed by its own non-profit foundation. It just recently hit version 3.0: http://haxe.org/manual/haxe3/features

It continues to make steps forward with new cross-platform development frameworks like openfl. http://www.openfl.org/