That's actually not true, at least if your definition of "Javascript semantics" isn't extremely broad.

This was the case with CoffeeScript. But the examples I gave either work with Webassembly (Grain, Bolero), providing their own runtime, or do some work to hide Javascript's data model to a large degree (F#, Purescript, ClojureScript).

What stays the same is that you are dealing with the DOM, User events occurring there and a metric sh*t ton of asynchronous APIs.