Fair enough. :) I've experienced a similar issue with interview questions where they often floundered on the question because they hadn't ever spent time digging under the surface. For example, I notice that a lot of (typically junior) developers seem to only think of JSON as a representation for hierarchical objects but never really spent time thinking about the typed-ness of its keys/values or the limits of what JSON can actually represent. An interview is a bad time to be confronted with that realization.

I cannot remember if I specifically mentioned refreshing on the DOM methods or not.

Well, it was a long time ago, so I'll give you the benefit of the doubt and just talk about what I've experienced. I go back and forth about how specific I should be about the type of questions I might ask. On the one hand, it seems kind of foundational that someone writing web frontends is aware of the DOM and how it works, even if they never directly interact with it. On the other hand, I think questions need to control as much as possible for the "preparation" factor because some people simply interview better or have more time to study.

It doesn't seem too crazy to me today that a competent FE dev these days might have spent their whole career in React, and therefore they don't really have a strong grasp on the DOM. If you had asked when I first started doing web FE development, that would have been crazy! But frameworks got a lot better and a lot more comprehensive since then.

I recently had an interesting experience asking a question involving dealing with UTF-8 encoding. I figured "everyone knows about UTF-8 right?" I retired the question pretty quickly once I realized that bit manipulation is not actually something you have to be even remotely familiar with in order to be a functional developer today in the vast majority of programming tasks, and therefore it wasn't even a good fizzbuzz-type test.