"Competant [sic] developers, even those who don’t specialize in JS, should be able to answer this question in 5-6 minutes. Therefore, this is a quick filter."

This is a false statement. I have programmed for years, but never in Javascript, so I have no clue what "add a cache to a Javascript function" even means. I can quite easily write code "that determines if a number is prime", but the assumption that everybody knows JS even if they don't "specialize" in it is problematic from my PoV.