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 signat

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.