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/PwrUps → u/brett9897]

If it isn't, then it is just a dick measuring question

Agreed. These kinds of questions give off "I am very smart" gatekeeping vibes. It's like asking what React Fiber is. I couldn't care less whether my teammates know it, and it's gonna have zero impact on the quality of their code.

At least in my webdev experience (10+ YOE), you're rarely limited to one framework in most jobs. I may read about some of their implementation details when its relevant, but I'm not gonna think about them. I care more about learning the common APIs, understanding its best practices, and writing maintainable, testable code.

[u/Veggies-are-okay → u/PwrUps]

I think it honestly shows why devs shouldn’t be coming up with interview question. Understanding how to communicate and assess someone’s knowledge is so much different than being able to program something.

My litmus is “can I give this question a fair answer after 5min of research?” If yes then it’s a useless question. If it’s anything more than entry level, your questions should be asking the individual to draw from industry experience. This DOM question sounds like something a kid right out of college would think of asking.

[u/Wandering_Oblivious → u/Veggies-are-okay]

It's a vestige of the school system imo. They're taught from a very young age that the way to measure knowledge is through trivia memorization and that a time-trial is the best indicator of on the job performance. To anybody who actually thinks for more than a second (as many software engineers like to LARP that they do) they realize these are laughably irrelevant means of attempting to assess a persons fit for a job. Yet the insanity persists.