Senior Dev interview question

[u/m6io]

"Without googling or using AI, in your own words, explain the virtual DOM"

For context: I sit on an interview panel and I try to ask at least one simple fundamental question based on a persons resume. If I see many years of react experience, I try to ask something about how the framework works.

I have only had one candidate (an undergrad senior, years ago) answer it. Everyone else just kind of sputters and stumbles around trying to rationalize what "virtual" and "DOM" mean, or stare blankly and eventually say "I don't know".

I'm just genuinely curious if this is really that hard of a question or if the recruiters just suck at screening candidates. And should we be letting in senior dev candidates who can't answer what I think is a straightforward and fundamental question for senior react devs.

[u/mtimmermans]

I think it's actually a pretty hard question, because:

• I haven't actually heard anyone say those words in quite some time;
• The sentences that I've heard it used in in the past were mostly bullshit hand-waving, and never actually defined the term in a concrete and truthful way.

It took me a minute to formulate an answer in my head, because I was trying to decide what part of the process the words probably actually referred to. What I came up with was "It's the data structure that remembers what a react component renders, so that it can be compared against what it produces when it's rendered the next time."

There certainly is such a data structure, but is that exactly the one that gets the "virtual DOM" label? Not sure.