All,
There is certainly a possibility that this change was a mistake, but it does
*not* appear cut-and-dried from reading the spec. Here is the actual text
from the DOM spec:
---
getAttribute
Return Value
DOMString The Attr value as a string, or the empty string if that
attribute does not have a specified or default value.
---
Depending upon how you interpret that (especially the definition of the
phrase 'does not have a specified or default value'), you could see it
either way. It certainly doesn't specify that you *can* depend upon a null
return value to determine that an attribute doesn't exist. In fact, it
doesn't even address the definition of a 'non-existent' attribute. You could
make the argument that it enumerates the valid types for the return value as
"a string, or the empty string", specifically excluding 'null'. Or you could
reasonably argue that all browsers *do* return null for undefined
attributes. But the reality is that it's not entirely dependable. Let me
demonstrate by example:
<div id='foo'>
var foo = document.getElementById('foo');
getAttribute('id')
IE7: foo
Firefox3: foo
getAttribute('className')
IE7: ""
Firefox3: null
getAttribute('tabIndex')
IE7: 0
Firefox3: null
getAttribute('xxx')
IE7: null
Firefox3: null
This puts us between a rock and a hard place. If we allow developers to
depend upon the return value being null, it won't always work. Do we then
have to put an explicit test in getAttribute() to force a null return value
in weird corner cases like tabIndex and className?
The only thing that appears clear to me in the spec is that you should
probably call hasAttribute() if you're not sure whether it's there or not --
which we would need to add to Element (and implement somehow on IE, since
it's not there by default). I would also be willing to consider changing the
type-coercion in getAttribute(), but only with the strong caveat that its
behavior is not specified when the attribute is 'not specified'.
Cheers,
joel.
On Sun, Aug 31, 2008 at 7:04 PM, Ian Bambury <[EMAIL PROTECTED]> wrote:
>
>
> 2008/8/31 Thomas Broyer [EMAIL PROTECTED]
>
>>
>> > Could someone from Google explain why there has been this diversion from
>> the
>> > path of 'least surprise'?
>>
>> Because that's how the DOM is defined:
>> http://www.w3.org/TR/DOM-Level-2-Core/core.html#ID-745549614
>>
>
>
> No it's not. w3.org's *recommendations" that you link to state that
> getAttribute() returns the string, or an empty string if the attribute is
> empty and there is no default. It doesn't appear here to recommend any
> return value if the attribute does not exist.
>
>
>>
>> > What suddenly became so wrong with returning what
>> > JS gives you?
>>
>> http://code.google.com/p/google-web-toolkit/source/detail?r=3568
>> Apparently, not all browsers give you nulls.
>
>
> That doesn't explain the sudden change.
>
>
>
>> On Aug 31, 4:09 pm, "Ian Bambury" <[EMAIL PROTECTED]> wrote:
>> > And now I can't tell the difference between an attribute which is
>> missing,
>> > and an attribute which is there but empty...
>>
>> Blame Microsoft eventually at first...
>>
> Why is it Microsoft's fault that Google made the change?
>
> I'm quite happy to blame Microsoft for anything and everything that has
> ever or will ever happen (I don't want to look out of place here) but if
> there is a genuine connection, all the better.
>
> The bottom line for me is that IE, FF, Opera and Safari all return null in
> raw JavaScript if the attribute doesn't exist - I really don't give a
> monkey's about the other browsers that GWT supports (!?) - and since when
> have Google worried about being officially compliant over getting the job
> done?
>
> Ian
>
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