The issue here is precisely is about recalling the syntax of a low-level approach, not whether you understand it conceptually. It’s the difference between being asked to make a request using curl, and constructing an HTTP request buffer manually without the help of a wrapper to tool to do it for you. It’d be the same as going to an interview, and having the interviewer ask you to complete an HTTP request on the spot using telnet and a keyboard. Sure, you can look it up, but when you do that you’re showing the interviewer you don’t already know.

Many devs know very well how to manipulate the DOM using JQuery, or construct the page they want using React. Most people do not use the low-level pure JS API. Conceptually I totally know how to make things happen in the DOM. Using the JavaScript built-in API, not really. Yeah it’s easy to learn in a weekend, that doesn’t change the fact that the API is tedious, hardly used in practice by most people, and rarely if ever necessary to use for performance reasons.

You say "The issue here is precisely is about recalling the syntax of a low-level approach, not whether you understand it conceptually" and in a scenario where an interviewer blindsided a candidate with such expectations I would agree, but that's not how we got to this topic.

The parent says, "Candidates were using their home computers had access to any reference material. There was no hurry. They could look things up," which is the opposite of that.

It even says they let candidates know ahead of time that's what the interview was.

I mean come on, people are on here and Reddit all the time acting like it's reasonable to grind leetcode for months to get a job, but a Saturday afternoon of studying the basics for an open book quiz on Monday is too much?

I should have said it’s about “using” the low-level syntax, and not “recalling”. You’re right that the story superficially claimed the interview was open-book and didn’t require memorizing the low level API, but it did say specifically that JQuery was not allowed. It was definitely not about conceptually understanding DOM manipulation.

As an experienced front-end developer, I can see from the story I might have personally bowed out of the interview too, not because I can’t use JavaScript to manipulate the DOM, but because I don’t want to. If the job involves doing that, I might think twice about that job.

You might be over-estimating how easy an open-book quiz is. I don’t think I’d pass an interview that asked me to write only x86 assembly, or write HTTP requests manually, or use pure JS to do what I know how to do in JQuery or React, even if it’s an open book quiz.