[benj111]

Well you need to know enough to know whether it's doing run time checks also.

And also whether it's generating less efficient code to satisfy the type safety requirement.

[Thiez]

It isn't. Typescript is basically javascript with type annotations. There is a shorthand for class member initialisation and for defining enums, but that's basically it. There are no extra safety checks inserted. You get compile-time typechecking and nothing else.