The true beauty of TS is that you can use it however you want. You want your TS file to be vanilla JS go ahead. You want to use the type system go ahead. There

The true beauty of TS is that you can use it however you want. You want your TS file to be vanilla JS go ahead. You want to use the type system go ahead. There doesn't seem to be much of a downside to me except for the developers that falsely think a type system will slow them down.