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Re: [css-regions] Invalid access in NamedFlowCollection

From: Alan Stearns <stearns@adobe.com>
Date: Wed, 10 Jul 2013 13:07:58 -0700
To: "www-style@w3.org" <www-style@w3.org>
CC: Erik Arvidsson <arv@chromium.org>, Boris Zbarsky <bzbarsky@MIT.EDU>
Message-ID: <CE030C31.2D3F9%stearns@adobe.com>
>On 7/9/13 1:12 PM, "Erik Arvidsson" <arv@chromium.org> wrote:
>
>>On Wed, Aug 29, 2012 at 4:34 PM, Alan Stearns <stearns@adobe.com> wrote:
>>>On 8/29/12 9:53 AM, "Boris Zbarsky" <bzbarsky@MIT.EDU> wrote:
>>>
>>>>On 8/29/12 12:46 PM, Mihai Balan wrote:
>>>>Currently the spec says that should a script try to retrieve an
>>>>inexistent object from a NamedFlowCollection, either by using an
>>>>out-of-range index or an invalid name, it should return **null**.
>>>>
>>>>I think it would be better to return **undefined** instead, for a
>>>>couple
>>>>of reasons:
>>>>
>>>>¡¤Currently all JavaScript and HTMLCollection-s return **undefined** for
>>>>invalid keys (e.g. Array, document.forms, document.querySelectorAll() )
>>>>
>>>>¡¤Also, in general, null doesn©öt mean that there©ös nothing there, but
>>>>actually that something might be there, but it©ös not a definite object
>>>>(yet)
>>>>
>>>>Anyone has any thoughts on this?
>>>
>>>Won't you get the "undefined" behavior for free if you use sane
>>>definitions of the supported names and indices in your prose?
>>>
>>>I agree that the undefined behavior is better, btw: it also makes "in"
>>>work correctly and such.
>>
>>I agree as well. I've made the change.
>>
>
>All the item and namedItem methods returns null in the DOM. It is the
>JS [[Get]] that returns undefined and not null. The following asserts
>hold true at all times:
>
>assert(collection.item(42) === null);
>assert(collection.namedItem('foobar') === null);
>assert(collection[42] === undefined);
>assert(collection['foobar'] === undefined);

I have reverted the change. The NamedFlowCollection methods now return
null if there is no NamedFlow with the provided index or name.

Thanks,

Alan

Received on Wednesday, 10 July 2013 20:08:30 UTC

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