[axlprose]

Yes, and even compared to ES7, Dart still fares rather well. Most people that doubt this seem to not have actually tried the Dart workflow and core libraries. The productivity gain from those two features alone makes it compelling against all other compile-to-js options, because what it brings to the table isn't just a fancy language with nicer syntax+semantics.

[nailer]

The dart std lib, at least the DOM manipulation bits, are indeed nice.

OTOH: JS has the largest module system of any programming language ever, which also tends to make it pretty productive.