I'd honestly consider these types of questions one of the poorest ways to test front end developers. The only reason I have learned some of that oddball stuff

I'd honestly consider these types of questions one of the poorest ways to test front end developers. The only reason I have learned some of that oddball stuff with JavaScript is because of some job interviews e.g. when I was earlier in my career, I used to Google things like "top 30 questions asked in a JS interview", etc, but I forget it after that until I'm about to look for another job. However I wouldn't do this type of learning any longer, since I wouldn't want to apply for a company asking these types of questions. In the end at work you should use ES6/TypeScript with linting, proper tests and these cases would never occur.