Do Not Use Dart or CoffeeScript

Do not use Dart or CoffeeScript. Just use plain JavaScript. If you must use something fancy, use TypeScript.

Dart is basically JavaScript with Java syntax & semantics. Java is bad. Goole do it because Google can't divorce Java.

CoffeeScript is no good because it's a layer of complexity, with ad-hoc syntax, and benefit isn't big enough. It will never be standard.

TypeScript is acceptable, because it's JavaScript compatible, with benefit of type system (math foundation❕),not hacker whims of idioms & styles & patterns & OOP crud.

see also What do Microsoft, Apple, Mozilla, say about Dart?