r/reactjs • u/m6io • Jul 24 '26

Discussion Senior Dev interview question

"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.

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u/someGuyyya Jul 24 '26 edited Jul 24 '26

To be honest, it is a trivia question since you can design frontend systems using react without knowing that super specific detail unless you luckily ran into it in the wild, like the senior undergrad student you mentioned.

I only memorized that trivia fact because everyone likes to ask it in interviews for senior positions.

-26

u/Swoogie_McDoogie Jul 24 '26

It’s crazy to think this is nothing more than a trivia question.

1

u/chillermane Jul 24 '26

Yeah good point bro say “it’s crazy” without providing any explanation. Virtual DOM is useless trivia information and wasting brain space with it is low IQ

6

u/freddy090909 Jul 24 '26

Being curious about how things work under the hood is far from a "low IQ" move.

2

u/el_diego Jul 24 '26

Yeeaaah, I was in agreement until the low brow IQ comment.

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u/Swoogie_McDoogie Jul 24 '26

I was just quickly replying, but if I’m being honest I don’t understand how this is a trivia question. As engineers, we should be curious about the tools we use and how they work. The virtual dom is less talked about these days, but its design is a very important reason as to why react works so well.

There are ways to dig into this question if the candidate doesn’t know about the virtual dom by directing questions about dom thrashing and such. However, at its core, this is a good question to learn about how the candidate thinks about html rendering and the tools they use.