I don't think that's the most important part of the doc, there is no reason for it to be bold.
Apart from that, are we going to put a label (except function) in all options descriptions all over the docs? That would look a bit clumsy to me.

I agree with @ChALkeR.

Apart from that, are we going to put a label (except function) in all options descriptions all over the docs? That would look a bit clumsy to me.

Exactly, so better just to accept functions everywhere. No one will likely ever do it or care, but if someone ever does find a use case for it, they won't be frustrated.

There is likely no use case for passing an Array or a Buffer as the options object, and it looks just as confusing, yet it's allowed.

I feel like there is a misunderstanding here. The original issue (#1981) has nothing to do with the use of functions as option objects. A function is being wrongly used as if fs.createWriteStream accepted a callback.

@targos #1982 (comment)

@ChALkeR I removed the bold style.

That would look a bit clumsy to me.

Yes, I agree.
My opinion is "if someone misunderstand the API, we should put a notice in API doc or improve API usage".

So currently we don't need to put the label "(except function)" in all API docs.

so better just to accept functions everywhere

-1, I have a same opinion with @targos .
We should prevent that users misunderstand that "wow, every function can accept callback!"

And we should discuss how document is improved in the docs repo. https://github.com/nodejs/docs

We should prevent that users misunderstand that "wow, every function can accept callback!"

The documentation wouldn't change in this case, so I don't see why the users would suddenly start trying to pass functions.

I'm going to close this for now, as it seems like there is some pushback and it has sat here for a while. cc @nodejs/documentation if they want to do anything with it?