Avoid Passing Null

[xjamundx]

Not sure if there is a rule for this yet, but it could probably done in a plugin.

Bad:

if (err) return cb(err, null)

Good:

if (err) return cb(err)

Why is that better?

getName(err, name = 'Default') {
   console.log(name); // might end up as `null`
});

[feross]

In other words: functions that get called with a parameter named err should only have one parameter.

[xjamundx]

I think people are used to typing cb(null, data) when things go well, so sometimes they do cb(err, null) when things go wrong.

There may be a case where you'd want to do cb(err, data), so I'm not sure you'd want to ban anything except null explicitly.

[dcousens]

functions that get called with a parameter named err should only have one parameter.

Unless you're callback is just a pass-through:

f(..., function (err, result) {
  console.log('Called back with ', err, result)

  callback(err, result)
})

[feross]

@dcousens Good point. So there's no way to reliably enforce this.

@xjamundx I think it would be a mistake to write code that assumes that the value will be undefined just because there's an err. You should check if there's an err explicitly every time.

[xjamundx]

Hmm probably a good point (this came up at work today and we found it was
happening in a few places). Probably we should avoid null in general at
this point, but community isn't there yet :)
On Tue, Mar 15, 2016 at 5:34 PM Feross Aboukhadijeh <
notifications@github.com> wrote:

@dcousens https://github.com/dcousens Good point. So there's no way to
reliably enforce this.

@xjamundx https://github.com/xjamundx I think it would be a mistake to
write code that assumes that the value will be undefined just because
there's an err. You should check if there's an err explicitly every time.

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