[scott_s]

He means that the semantics of Dart - including the data types provided by Dart - are different from JavaScript. This is in opposition to TypeScript, which is a superset of JavaScript, which means that it necessarily shares JavaScrips semantics.

If your example bothers you, consider that JavaScript just happens to be a target language for the Dart compiler. That is, it takes a program with Dart's semantics, and figures out how to map those to JavaScript semantics. That there is a mapping is not all that interesting, as such a mapping will exist from any Turing complete language to any other.

[lindenr]

Really? Wow, that's cool. Can I have a reference?

[scott_s]

I'm really just describing how a compiler works. Are you looking for references on the compilation process? There's a classic series called "Let's Build a Compiler" (http://news.ycombinator.com/item?id=1727004) available online that walks through building a simple compiler. Then there's also actual textbooks, but I was not impressed with either of the two textbooks I've had on the topic. Many people recommend "Compilers: Principles, Techniques, and Tools" (http://dragonbook.stanford.edu/) also referred to as just the dragon book. If you're not averse to textbooks, you may also want to check out Michael Scott's "Programming Language Pragmatics" (http://www.cs.rochester.edu/~scott/pragmatics/).