[whatwg] Overriding functions in DOM Storage

Jeremy Orlow jorlow at google.com
Tue May 26 19:44:41 PDT 2009

No one else (especially from Mozilla or Microsoft)?  I was hoping to get a
consensus here (and maybe even things spelled out more clearly in the spec),
so that all the implementations could be headed in the same direction.  :-)

On Fri, May 22, 2009 at 8:03 PM, Maciej Stachowiak <mjs at apple.com> wrote:

> On May 22, 2009, at 5:41 PM, Jeremy Orlow wrote:
>  What is the behavior of the following supposed to be?
>> window.sessionStorage.removeItem = function(x) { alert("Wait, this
>> works?"); };
>> window.sessionStorage.removeItem('blah');
>> alert(typeof window.sessionStorage.removeItem);
>> Safari shows 2 alerts, and the second one says 'function'.
>> IE8 says "object doesn't support this property or method" if line 2 isn't
>> commented out.  It returns type string when it is.
>> Mozilla also won't run if line 2 is there, but it returns type object for
>> line 3.
>> It seems to me that if IE8's behavior is correct, those parameters should
>> be marked as read-only since overriding them could only be used to shoot
>> yourself in the foot.
>> If Safari's implementation is correct (and it's good for the
>> implementations to be overridable), then I believe there needs to be some
>> safe way to make .clear() usable again.  (Otherwise, once you override
>> removeItem() and clear(), there's not really any way to recover.)  The spec
>> would also need to make it clear that removeItem, setItem, etc are special
>> and should not be serialized to disk.
>> Apologies if this is clear in the spec and I somehow missed it.  But, if
>> not, I think a clarification might be necessary.
> DOM methods are normally overridable. That would make the Safari behavior
> correct. If we want the behavior to be different in this case, then the spec
> should spell that out. Perhaps part of the issue here is that the definition
> of the [NameSetter] extended attribute in Web IDL doesn't make clear whether
> or not name setter behavior takes precedence over setting existing
> predefined attributes or methods.
> Regards,
> Maciej
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