Array.prototype.slice web-compat issue?

Andrea Giammarchi andrea.giammarchi at gmail.com
Tue Sep 10 10:37:15 PDT 2013


I see one of two problems mentioned in my other topic is already discussed
here so I'd like to add this question that will most likely break the web:

  1. will `[].slice.call(arguments)` produce a pointless instanceof
Arguments ?
  2. will `[].slice.call(document.querySelectorAll('*'))` produce an
instanceof Static NodeList ?

AFAIK 99% of libraries out there believe that slice.call will return an
Array of the current realm.
Wouldn't be wise to distinguish between explicit
`Array.prototype.call(context)` VS `context.slice()` so that only latter
one will produce the magic ES6 would like to add ?

Thanks for any clarification.


On Tue, Sep 10, 2013 at 4:26 AM, Jan de Mooij <jdemooij at mozilla.com> wrote:

>
> ----- Original Message -----
> > On 9/9/13 12:01 PM, Allen Wirfs-Brock wrote:
> > > Yes, that's what I meant.  It's clear what the test is doing but I'd
> like
> > > to understand a bit better what the application logic thinks it's
> doing.
> >
> > It's a bit sad that the bug doesn't have info on that.  :(
> >
> > Jan, do you recall what the exact issue was with Jira here, by any
> chance?
>
> Unfortunately not :( IIRC an iframe for one of the widgets passed an Array
> to its parent frame, and the parent frame used slice + instanceof, but I
> don't remember the details after two years...
>
> Jan
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