Here are things I have had CS grads demonstrate an inability to do within an hour or more timeframe:
Make a loop that sums up numbers in an array.
Write an algorithm that sorts a list of three numbers. I watched students spend an hour making a bunch of if statements to try and cover all cases... ultimately getting it wrong.
Compute the accuracy by computing the number of matches between two lists and dividing between the length.
Split a list into two lists.
Generally the failure mode is to find something vaguely near the task, but overly-sophisticated from google. Then wrestle with trying to hack it into working by frantically scouring stackoverflow etc for their next code adjustment.
You're just describing leetcode here. Not something most people even do in their day-to-day.
A lot of frontend devs don't even work with the DOM directly after having spent years with React. Could they do it? probably. Are they prepared for DOM-related manipulation questions on a whiteboard? nope.
What exactly is leetcode? as opposed to just asking someone to prove they know the stuff listed on their resume.
And suppose there are a lot of cheaters out there who don't know the things on their resume, even including earning a degree without ever having to write a working program on their own. How would you screen them out?
Make a loop that sums up numbers in an array.
Write an algorithm that sorts a list of three numbers. I watched students spend an hour making a bunch of if statements to try and cover all cases... ultimately getting it wrong.
Compute the accuracy by computing the number of matches between two lists and dividing between the length.
Split a list into two lists.
Generally the failure mode is to find something vaguely near the task, but overly-sophisticated from google. Then wrestle with trying to hack it into working by frantically scouring stackoverflow etc for their next code adjustment.