All I really wanted was to allow type annotations in JavaScript. So you wouldn't need a compile step while running (JavaScript would just ignore the type signatures), but TypeScript could check it whenever. I believe this is the approach Python uses.
I think there were discussions of doing that at some point, but it seems to have gone nowhere.
JS isn't going to get compile time anything. There was an attempt at adding "strong mode" by one of the google / chrome teams iirc and that went nowhere.