It's gradual typing. Yes, it's full of holes, that's the whole point. There are other languages with strong, powerful type systems that compile to efficient Ja

It's gradual typing. Yes, it's full of holes, that's the whole point. There are other languages with strong, powerful type systems that compile to efficient JavaScript, such as (in order of power) Elm, OCaml, PureScript and Idris. Those four are just arbitrary examples however, there are quite a few more.