Prevent callback in try block

[LinusU]

I misstake that I've seen quite a few people doing is calling a callback in a try block, not thinking about the fact that any error occurring in the callback will now be catched as well.

Example bad code:

try {
  cb(null, JSON.parse(data))
} catch (err) {
  cb(err)
}

What the authors intent really was:

let parsed
try {
  parsed = JSON.parse(data)
} catch (err) {
  return cb(err)
}

cb(null, parsed)

I understand that this might be a bit hard to implement, but I still think that it at the very least is worth discussing.

Would it be unreasonable to assume that every variable named cb is a callback? It seems to be the accepted practice to name it as such, in the same way that we have rules that assumes that variables named err are errors, and needs to be handled.

What do you think?

[dcousens]

cb, next, done, callback, fin, finish, free, resolve?, reject? ... I feel like this could go on forever.
I agree conceptually though :)

[feross]

Agree conceptually. The first step is to propose this in eslint. I'd prefer to not maintain our own rules, since that's a ton of work.

[feross]

I'm going to close this issue due to lack of progress.

This rule isn't really something that I, or any of the other standard collaborators that I know of, plan to implement at the moment. That's not to say it's a bad idea. I would accept a PR that enabled it, but the first step would be to get it added to ESLint or one of the ESLint plugins that we already depend on.

Then, send a PR to add the rule to standard, or open a new issue and I'm happy to do it.