Rest parameters and default parameters

[MartinKolarik]

JSHint reports Regular parameters cannot come after default parameters if you use both default parameter and rest parameter, but I think this is a valid use case:

function f (x = 0, ...y) {}

[Nicolab]

Hello,

+1

main.expr.parse = function parse(expression = '', scope) {
};

Regular parameters cannot come after default parameters

An idea to fix this ?

[rwaldron]

Sorry, lost track of this one, thanks for the bump.

[Nicolab]

Super :)

[UltCombo]

Should the "Regular parameters cannot come after default parameters" error even exist at all?

AFAIK this is valid:

function f(a = 1, b) {
    console.log(a, b); // 1, 2
}
f(undefined, 2);

Yet JSHint throws the aforementioned error.

[caitp]

you're right, it doesn't make much sense :< (https://people.mozilla.org/%7Ejorendorff/es6-draft.html#sec-destructuring-binding-patterns-runtime-semantics-iteratorbindinginitialization)

[UltCombo]

It could be downgraded to a warning/config option IMO (e.g. useful for people that consider it a bad practice).
But it is not much of a choice when you're passing callbacks to 3rd-party APIs.

[UltCombo]

If downgrading to a warning/config is preferred, I guess a new issue should be opened to track the progress on it.

If the error is removed altogether, then it fixes both OP's and my issue.

[caitp]

ever since at least draft rev 20 (from 10/2013), the workings have been "initializers can go anywhere, and just replace undefined values". I don't have any older drafts, so maybe this was different at some point. Anyways, we should probably just delete the warning, it's kinda bogus

[caitp]

@rwaldron wdyt?

[rwaldron]

There are two things here:

1. Formal rest parameters are restricted to last position.
2. There is no restriction on defaults

[lukeapage]

Any preference on whether to convert to a warning or remove outright ?

Not sure what you mean by There is no restriction on defaults but if its that function(a = b,b){} fails, that is covered in other issues (and fixed in a PR)