"Knowing TypeScript" is...functionally trivial, though. If one can read JavaScript and can't get enough from context to read TypeScript, I question their knowledge of JavaScript!

Perhaps writing it is a bigger ask--a twenty minute session of reading and poking at the language in VSCode did it for me, but maybe I'm secretly some kind of TypeScript savant--but this just plain should not be a problem for anybody who's up on modern JS.