Interpreted that's right, in fact it's super slow and adding types adds up to parsing time. Javascript is jitted. Python types serves no purpose if not for documenting or letting the lsp doing some lightweight type checking. And btw typescript introduced many breaking changes and the spec is managed by microsoft something you don't want for the open web. What we would really benefinit from would be having WASM being able to do more inside the browser, like rendering, managing user input, accessibility, dom manipulation. Then u could compile your favorite static types lang down to wasm. Hell even a strictier version of TS could be made to do that, iirc there's something similar called assembly script

Python containing type hints doesn't get transpiled the way typescript does. The transpiling rewrites the TS to varying degrees depending on the target and the extra TS features being used.

Python "just" (that word is doing a lot of work) updated the interpreter to ignore the type hints. It still runs the same way as code without hints.

There's a bit more going on with TS that you couldn't just have the runtime ignore the types.