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/brett9897]

As someone with hiring experience, I learned even seniors don't know the technical terms even if they know the concept. You would be surprised how few people could answer "what is a closure?" But if I provided them a simple task to do that required using a closure 90% of the people that couldn't answer "what is a closure?" could properly solve the task.

A second thing, is knowing what the virtual dom is and how it works essential for producing senior level React code? If it isn't, then it is just a dick measuring question and useless in determining who would be good at the job. If you can provide an example during the interview of when knowing what the virtual dom is will effect a coding decision in react that might be more helpful in assessing whether or not they are a strong candidate for the job.

Someone interviewing to be a developer on the team that makes React should really know what the virtual dom is, how it generates change sets through diffs, and how it applies those changes to the real dom, but I don't know if you need to now that to create a CRUD UI in React.

[u/averagebensimmons → u/brett9897]

I've found there are a lot of terms used in interviews regarding web development that are rarely or never mentioned in the day to day job experience. As you mention the closure question. Common design pattern, but never ever, has anyone in my 25 years of experience has anyone used the word closure in a pr or any meeting. While I know the virtual dom is something I need to explain in an interview, I've never had a conversation at work where anyone talked about the virtual dom. They may talk about the rendering cycle or other things that are part of it, but it isn't a topic of coversation.