> Because you need a ridiculously complex type system to model JS's behavior and then in the end don't even get soundness for all your trouble? most type syst

> Because you need a ridiculously complex type system to model JS's behavior and then in the end don't even get soundness for all your trouble? most type systems are not sound. Co-, Contra- or In-Variance is a extremly hard problem there are not many languages out there who offer complete soundness over all types. most problems of typescript happen because people use interfaces a lot, since they are type hints for javascript objects, however once you start with classes way more and use strict mode, stuff is way better than just using js.