Avoid reassign parameters

[foisonocean]

I think it's very useful: http://eslint.org/docs/rules/no-param-reassign.html

[dcousens]

Ecosystem breakage isn't going to be pleasant.
And honestly, you could just as easily encourage people not to use the arguments object except in limited circumstances.

[yoshuawuyts]

Huge no no on this one, this would make using standard impossible for me. Default params using `foo = foo || {}` is staple. Also using arguments is a common thing to do

…

On Fri, Mar 10, 2017, 14:54 Daniel Cousens ***@***.***> wrote: Ecosystem breakage isn't going to be pleasant. And honestly, you could just as easily encourage people *not* to use the arguments object except in limited circumstances. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#818 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACWleh8QP8EgS0ZnQWaCy0TYU_5a6Ewdks5rkVX3gaJpZM4MZE3M> .

[feross]

@yoshuawuyts is right that foo = foo || {} is extremely common. Or even:

function foo (opts) {
  opts = Object.assign({
    default1: true,
    default2: 'cool string'
  }, opts)
}

Also, using arguments isn't really a good idea when we have ...args now:

function foo (...args) {
}

I'd prefer to pass on this rule, even though I agree at a high-level that it sounds desirable. It's just not practical in the real-world.

[dcousens]

@feross I think if you could avoid arguments usage, generally, that would be good.
Its only truly useful in an .apply like context no?

[yoshuawuyts]

@dcousens yeah I think so, although it's very common - just in the last week I've written 2 new modules built entirely around this. In the example below there's no escaping using arguments:

// written just for show, idk there might be bugs but yeah.
Emitter.prototype.emit = function (eventName) {
  var event = null
  var args = []
  for (var i = arguments.length - 1; i >= 1; --i) args[i] = arguments[i]
  var events = this._events[eventName]
  if (!events) return
  for (var j = events.length - 1; i >= 0; --i) {
    event = events[j]
    event.apply(event, args)
  }
}

Also, using arguments isn't really a good idea when we have ...args now

Like with most things there's probably fancy ways to write this using new language additions, but I'd rather we allow people (like me ✨) to use standard without forcing them to tail new specs. I mean: rest params doesn't even have widespread support yet.

[feross]

Like with most things there's probably fancy ways to write this using new language additions, but I'd rather we allow people (like me ✨) to use standard without forcing them to tail new specs

Sure thing. Wasn't trying to enforce that on folks. I was just saying that I'm not too worried about arguments implicitly getting modified when we have rest params as a great up-and-coming alternative.

Also, most functions that use arguments don't use named arguments. It's usually either-or.

[feross]

One last thing: rest params have more support than you think! Check it out!

We're rapidly approaching a world where you can use the new fanciness and forgo preprocessor complexity like babel. Can't wait.

[dcousens]

Also, most functions that use arguments don't use named arguments. It's usually either-or.

Maybe that is something we could look into enforcing?