Oh god please I hope they have. In my experience, dynamically typed scripting languages struggle to keep up with the rigorous structure enforced by statically typed languages once the project gets large enough.

Yes, in theory you _can_ write big projects well in dynamically typed languages, but in practice you get a mess of undocumented interfaces and unit tests that don't quite catch the plethora of errors not present when a static type system is in place.

I think Typescript is a great middle ground between the loose running JS hipsters and the Haskell loving Hindley-Milner type system CS researchers. You can enforce the type restraints that you want (I personally am strict about explicit "string | null" declarations) but you're still hip enough to draw the JS talent.