Well, JS is paired with a single-threaded execution model, so you only have concurrency to worry about. C#, Java has proper multithreading as well, that gives another dimension to the problem.

Kotlin has multithreading, and it also puts `suspend` in the type system.

Some more examples: Rust, Python (with most/all? type checkers), C# all bake this into their type systems.

This is more due to the fact that Kotlin doesn’t control its backend and is designed to work with a language that already includes this model, js.