util: add tagOnly option to util.inspect

[devsnek]

Returns the inspected value without inspecting the keys/values of the
object.

I am requesting to add this feature mostly so that it can be used with console.table, but I'm sure people will use it for other things too.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

util

[Trott]

Documentation correction needed, but other than that, looks OK to me. No opinion as to whether this should be exposed as proposed here or instead added to internal/util.js somehow. I think I'm in favor of exposing it, but I don't have a strong opinion.

[Trott]

This should say showNone rather than showHidden I think?

[devsnek]

i was originally going to throw it in internal but i couldn't think of a good way to split this up from util.inspect that didn't kill perf or require large amounts of duplication. I think its probably fine to just have the option.

[cjihrig]

Code looks OK to me. I don't really like the name showNone though. Perhaps something like tagsOnly or similar. Sorry for the bikeshed.

[devsnek]

@cjihrig no problem! i don't really like showNone either 😄

requested change has been implemented

[devsnek]

i like tagOnly and flat, if people have other ideas please let me know

[jasnell]

there may need to be additional detail about what is meant by "tag" here.

[devsnek]

i was thinking the same thing, but i wasn't sure what to write, so i just hoped the example below would be enough

[BridgeAR]

If `true`, only the object type (tag) will be shown, ignoring all keys and values. Printing is like the same object being empty. Defaults to `false`.

Something like that?

[BridgeAR]

@devsnek what about calling it metaOnly? And about exposing it - I personally do not know any use cases besides the one you mentioned and I am not sure if it makes sense therefore but I do not have a strong opinion on it.

[devsnek]

I can't think of a good way to not expose it

[BridgeAR]

@devsnek you are right, I meant not documenting it. There is another option not documented at the moment, so it would work similar.

[devsnek]

@BridgeAR i have no qualms with that, shall i remove the docs?

[devsnek]

@BridgeAR @jasnell @Trott @cjihrig i removed the docs, it should be good to go now

[devsnek]

i'm just gonna close this since something moderately similar can be achieved with -1 depth and the pr appears to be dead

[BridgeAR]

@devsnek I like the thought about the depth option! That is probably indeed a better way of doing this.

Thanks a lot for the PR anyway and I am sorry that I did not look into it earlier again!