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Re: Non-constructible constructors and Arrays

From: Brendan Eich <brendan@mozilla.com>
Date: Wed, 27 Jul 2011 22:58:07 -0700
Cc: Alex Russell <slightlyoff@google.com>, public-script-coord@w3.org, Cameron McCormack <cam@mcc.id.au>
Message-Id: <4923645A-ECEB-451A-8DEE-CEA830BF724F@mozilla.com>
To: Garrett Smith <dhtmlkitchen@gmail.com>
On Jul 27, 2011, at 10:32 PM, Garrett Smith wrote:

> On 7/27/11, Alex Russell <slightlyoff@google.com> wrote:
>> The topic of WebIDL's last call just came up at the TC39 face-to-face,
>> and one issue I've flagged but not posted here yet is the topic of
>> non-constructible constructors. Section 4.3.5 contains an explicit
>> example of a behavior that I'd like to see repaired:
>>    // from: http://www.w3.org/TR/2011/WD-WebIDL-20110712/#Constructor
>>    var z = new NodeList(); // This would throw a TypeError, since no
>>                                          // [Constructor] is declared.
> Existing browser behavior seems fine by me.

Hi Garrett -- the issue isn't breaking existing behavior, it is extending it so you can "new" a NodeList. Is there a reason not to do this? Regularity in languages and APIs is better than irregular and seemingly arbitrary restrictions, all else equal.

>> On the topic of Arrays, I know it has come up before that there are
>> DOM collection types, in particular NodeList, which should be Array
>> subclass instances.
> The problems with that were quickly uncovered on:
> "[whatwg] Adding ECMAScript 5 array extras to HTMLCollection"

You mean the thread containing your message:


It's hard to tell what problems you mean, apart from browser differences that would be fixed by specifying better normative behavior, via WebIDL and relevant DOM and Web API specs. I mean, sure -- some browsers don't do the right thing with array generics on NodeList. This is not a reason to reject the idea of extending NodeList's spec (implementations to follow) so the generics work.

Received on Thursday, 28 July 2011 05:58:37 UTC

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