I thought that questions which ask to make a list of things are off-topic here; however, I can't find anything in the rules which tells that it is the case.
There is a popular variant of questions which lead to answers containing only one or few elements from a list, such as What non programming books should a programmer read? Those are off-topic, but this case is different.
Here, the answer won't limit itself to one or few elements from a list. Instead, it can:
Either produce the full list of all functions returning
nulland a list of those which return
undefined, eventually providing also a link to the documentation which contains those lists in the first place,
Or explain how to generate such list by parsing documentation such as MDN,
This question is also different from questions asking for a list of examples. Here, there is the right answer.
In all cases, the question is absolutely not “I'm lazy, do my job for me”-style question. I find it well written and constructive, and among the close reasons, no seem to match.
Is this question off-topic?
If yes, what should be the close reason?