DDC is an alternative to the dart2js compiler. It supports "strong mode" which provides better compile time checking, and produces more idiomatic Javascript.

Dart has a large team behind it, an awesome package management infrastructure, a "Dart native" angular 2 library.

Dart is just another junk food programming language in the same vein as Java (with some of the same people involved). If you really want to learn what a "strong mode" is, learn OCaml. Good job Bloomberg for Bucklescript.