[whatwg] Adding ECMAScript 5 array extras to HTMLCollection

[Maciej Stachowiak]

On Aug 4, 2010, at 2:40 PM, Jonas Sicking wrote:

> On Wed, Aug 4, 2010 at 11:10 AM, Alex Russell <slightlyoff at google.com> wrote:
>> Sorry for the lagged response,
>> 
>> On Fri, Jul 30, 2010 at 2:56 PM, Oliver Hunt <oliver at apple.com> wrote:
>>> 
>>> On Jul 30, 2010, at 2:46 PM, Alex Russell wrote:
>>> 
>>>> Wait...what? Shouldn't some sort of NodeList be mutable? And shouldn't
>>>> JS support immutable Arrays? We need to fix both of these APIs, and we
>>>> keep heaping back-pressure on JavaScript's Array without any
>>>> reasonable resolution because we're not exploring how to make Array
>>>> subtypes work as we want them to for all the use cases (like this)
>>>> that we care to express.
>>> 
>>> What would you expect a mutable NodeList to be?
>> 
>> A good example would be the result of document.querySelectorAll().
> 
> Why couldn't querySelectorAll return a normal Array?

I think in principle it could, but it might be too much compat risk to do now.

Returning a fully mutable array would also remove the opportunities to cache and reuse the return value, since each result would really need to be distinct if they are mutable.

Regards,
Maciej