[lettergram]

I've never had a job where I was required to code in JS. However, I have had one interview where I went headfirst into SCSS when the job actually only required C/C++ skills (it was work on a computer vision system).

The thing is, I think most interviewers ask for what they are most comfortable with, so they can evaluate. Which is why questions related to JS are probably so common for companies like Google, Facebook, Twitter, etc. even if you don't actually need it or use it.

However, I would also point out that JS is pretty easy, if you know any of the standard languages you'll be fine. Although, I do find it humorous because JS is basically one of the worst constructed languages I know of (even though I use it daily...).