fs.mkdir is inconsistent in the number of arguments passed to the callback , when completed.

[ryan65]

Version

16.14

Platform

Window/Linux

Subsystem

No response

What steps will reproduce the bug?

//call mkdir with to create a non existing directory and then when complete call it again with the same directory.
fs.mkdir('c:\\temp\\testdirnonexist',{ recursive: true }, function(){
       console.log('first time', arguments.length); //result 2
       fs.mkdir('c:\\temp\\testdirnonexist',{ recursive: true }, function(){
          console.log('second time', arguments.length); //result 1
       });
});

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior?

Always return the same number of arguments.
This is important for example when you pass an async waterfall callback to mkdir.

What do you see instead?

if the directory exists only 1 arguments will be returned (error argument which is null)
if directory is created then it returns null, and the path.

Additional information

No response

[daeyeon]

https://github.com/nodejs/node/blob/master/doc/api/fs.md#fsmkdirpath-options-callback
According to the document, it seems a correct behavior but there is a missing description for the parameter. I will create a PR to improve it.

The callback is given a possible exception and, if recursive is true, the first directory path created, (err[, path]). path can still be undefined when recursive is true, if no directory was created.

[daeyeon]

Please let me know if the doc fix isn't enough to resolve your issue.

[ryan65]

Hi
Thanks Daeyeon
I think the documentation now will be clearer, although I personally am still not sure what the most intuitive behavior should
be, regarding the returned result, since currently its inconsistent. but the documentation at least clarifies this.