Except for the last two, these would be a "learn on your own time thing, " since we have Array.sort, and it's more important to know how to use the argument to sort things how you want. I personally would want a candidate who spent their own time understanding things that were more relevant to the job at hand unless they were just curious about algorithms.

In React, at least, linked lists have virtually no applicability, because you can't do anything with the links except read them in an immutable world. Obviously, reversing the list involves replacing the entire list, so you could do that, but given you can't do anything else, what's the point?

There's probably a RegEx solution to the last problem that's better, but honestly with RegEx it's more important to know how to research the issue than to have the solution off the top of your head. I would never in a million years ask a candidate any of these or accept a job if the interview focused on these.