Well, testing 4 == '4' is pointless in my opinion, because you should never use the '=='-type equality in JavaScript. I never use it, so I don't even know what that evaluates to. You should always use ===, and set up a linter to enforce that.

What I think is valuable to understand is the concept of truthy and falsy, as I've seen even some experienced JavaScript programmers struggle with that. Maybe that could be a decent interview question.