You know it would be completely transparent right? Just gets transpiled into .__add__(obj)

We already saw this play out in Scala. People end up abusing these to create absolutely unreadable "DSL"s. Even when it's tastefully done, for example the "!" and "?" operator for messages in Akka, it's not better than the names "tell" and "ask".

Fair enough.

The explicit goal of TypeScript is to be JavaScript, with types — i.e. not introduce any features not likely to land in an ECMAScript spec.

Which is a shame because JavaScript is constrained due needing backwards-compatibility above all (among other issues) but TypeScript isn't

Not much of a shame IMO - there are plenty of other languages that transpile to JS without those goals, if you don't care about backwards compatability and 1:1 mappings to vanilla JS.

On the other hand, there's only one language that I'm aware of - TypeScript - prioritizing these things, which is a major selling point of it to me. I don't want yet another leaky abstraction, or yet another runtime heavy enough for those abstractions to not leak.

I just want enough types for my intellisense to work right, and for my sorry ass - spoiled by years of nothing but static typing systems - to be able to code without drowning in a veritable sea of uncaught type errors to debug, when I poke frontend stuff.

Typed and those features? there isn't a single one. But yeah, maybe what I need is a fork of TypeScript with those features (or maybe some sort of plugin)