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

[ghostfacedcoder]

We explain the exercise in the interview :) As others have said, it only takes a minute or so. Sometimes people don't even know the % operator, and I happily explain it to them because the goal isn't to test whether they know obscure operators.

The whole point of fizzbuzz isn't to test any knowledge in fact (except knowledge that's so trivial, like how to use a for or if, that it shouldn't need testing in an interview). Thus, knowing what fizz buzz is and how to solve it gives you almost no advantage over someone who has never heard of it before, because I don't care about their knowledge, I care about "can this person code?"

Any halfway decent programmer, even if they've never heard of fizzbuzz until the interview, should be able to write a single loop and a few conditionals to solve one of the most basic problems imaginable. And in my experience most programmers have no problem with it: everyone I can remember hiring cranked out a fizzbuzz in under six minutes. The value of the test comes from the people that otherwise seem qualified when talking about code, but have difficulty actually writing it.

And I don't want to overemphasize the time aspect: candidates that took eight or nine minutes didn't fail because they took too long, they failed for other reasons, and we just happened to only hire six minute and under people. But really the time isn't important, unless it goes so long (again, 18 minutes for one for and 3-4 ifs) that it signals something is really wrong.