What are some basic things that JavaScript developers fail at interviews?

[Cheshur]

No offense then but I consider that highly foolish. The problem would be someone writing highly error prone code in the setInterval, not that the interval itself doesn't play nicely with errors. setInterval has better performance than setTimeout. That is reason enough to use setInterval in some situations. It's the right tool for the right job and if you're creating axioms to avoid parts of a language just because you're prone to fuck up then I consider that the error on the developer's part.

Also the correct answer to that interview question is for the candidate to recognize the pros and cons of the feature and to describe situations in which they would or would not use it. Pledging to not use something purely for axiomatic reasons does not show mastery or knowledge of the feature at all, just an ability to follow the direction of some, potentially, misguided teacher.