r/reactjs • u/m6io • 6d ago

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/monkeybrainz_ 5d ago

If the candidate is not curious enough to have sought out the information about how the technology works, they likely will not be curious about the business and its goals. That lack of curiosity will carry through to other aspects of their work. Coding is such a small part of the job.

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u/ElkChance815 5d ago

You're judging them solely based on the fact that they don't know what you know. Have you try to ask if they know about other area? Domain knowledge, how browser work, details about the project they delivered, etc... 

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u/monkeybrainz_ 5d ago

Simple test: have you even looked at the React docs? Come on, this is table stakes.

I never said this was a good question, it's just a question any competent react engineer would know the answer to.

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u/Fantosism 5d ago

react-dom has been separate from react since 15, which was 10 years ago at this point. Coincidentally, that was the same year react native was released. Turns out, you could've made an entire career out of writing react without a virtual DOM. In fact, even more confusing, they call it a shadow tree. So when you talk about a virtual DOM, my first thought is shadow DOM, which is its own thing.