Note for DOM L3 Core SE

[Travis Leithead]

While implementing some improvements to getAttribute in IE8, we actually checked in code that is conformant to what the spec says about the return value:

Return Value
DOMString
The Attr value as a string, or the empty string if that attribute does not have a specified or default value

Once this code was in, we immediately hit app and site compat problems because we always returned a string--an empty string--if the "attribute [did] not have a specified or default value".

As it turns out in practice, all browsers actually implement this a slightly different way: they return the value as a string, or null if the attribute does not have a specified or default value. In other words, if there is no entry for the requested attribute in the NamedNodeMap, then null is returned.

IE8 is being fixed to be conformant with what everyone else has implemented, I just thought I would pass this along to whomever is doing the DOM L3 Core Second Edition so that it might be recorded in that spec, an errata, or so that we can discuss.

Travis Leithead - OM Program Manager - Internet Explorer

[Maciej Stachowiak]

Post by Travis Leithead
While implementing some improvements to getAttribute in IE8, we
actually checked in code that is conformant to what the spec says
Return Value
DOMString
The Attr value as a string, or the empty string if that attribute
does not have a specified or default value
Once this code was in, we immediately hit app and site compat
problems because we always returned a string--an empty string--if
the "attribute [did] not have a specified or default value".
As it turns out in practice, all browsers actually implement this a
slightly different way: they return the value as a string, or null
if the attribute does not have a specified or default value. In
other words, if there is no entry for the requested attribute in the
NamedNodeMap, then null is returned.
IE8 is being fixed to be conformant with what everyone else has
implemented, I just thought I would pass this along to whomever is
doing the DOM L3 Core Second Edition so that it might be recorded in
that spec, an errata, or so that we can discuss.

Anne and I suggested an errata for this a few years back, but the DOM
folks were not receptive at the time, out of consideration for server-
side Java DOM implementations:

http://lists.w3.org/Archives/Public/www-dom/2005OctDec/0011.html
http://lists.w3.org/Archives/Public/www-dom/2005OctDec/0025.html

See the thread for more discussion.

I also at the time raised another compatibility issue that I thought
should be fixed in errata:

http://lists.w3.org/Archives/Public/www-dom/2005OctDec/0024.html

The short version is that DOM forbids inserting nodes into a different
document than their ownerDocument, but browsers allow it (in at least
some cases).


These two issues are Safari's only failures in the official DOM Level
1 Core test suite. I believe neither of these failures can be fixed
without significantly breaking web compatibility.

Regards,
Maciej

[Jonas Sicking]

Post by Maciej Stachowiak

Post by Travis Leithead
While implementing some improvements to getAttribute in IE8, we
actually checked in code that is conformant to what the spec says
Return Value
DOMString
The Attr value as a string, or the empty string if that attribute does
not have a specified or default value
Once this code was in, we immediately hit app and site compat problems
because we always returned a string--an empty string--if the
"attribute [did] not have a specified or default value".
As it turns out in practice, all browsers actually implement this a
slightly different way: they return the value as a string, or null if
the attribute does not have a specified or default value. In other
words, if there is no entry for the requested attribute in the
NamedNodeMap, then null is returned.
IE8 is being fixed to be conformant with what everyone else has
implemented, I just thought I would pass this along to whomever is
doing the DOM L3 Core Second Edition so that it might be recorded in
that spec, an errata, or so that we can discuss.

Anne and I suggested an errata for this a few years back, but the DOM
folks were not receptive at the time, out of consideration for
http://lists.w3.org/Archives/Public/www-dom/2005OctDec/0011.html
http://lists.w3.org/Archives/Public/www-dom/2005OctDec/0025.html
See the thread for more discussion.
I also at the time raised another compatibility issue that I thought
http://lists.w3.org/Archives/Public/www-dom/2005OctDec/0024.html
The short version is that DOM forbids inserting nodes into a different
document than their ownerDocument, but browsers allow it (in at least
some cases).

Yup, this is a bad situation indeed. Basically browsers are stuck with
no good way out: Be compatible with the spec, or be compatible with the
web. Of course any serious web browser is going to choose the latter.

/ Jonas

[Maciej Stachowiak]

Post by Jonas Sicking

Post by Maciej Stachowiak

Post by Travis Leithead
While implementing some improvements to getAttribute in IE8, we
actually checked in code that is conformant to what the spec says
Return Value
DOMString
The Attr value as a string, or the empty string if that attribute
does not have a specified or default value
Once this code was in, we immediately hit app and site compat
problems because we always returned a string--an empty string--if
the "attribute [did] not have a specified or default value".
As it turns out in practice, all browsers actually implement this
a slightly different way: they return the value as a string, or
null if the attribute does not have a specified or default value.
In other words, if there is no entry for the requested attribute
in the NamedNodeMap, then null is returned.
IE8 is being fixed to be conformant with what everyone else has
implemented, I just thought I would pass this along to whomever is
doing the DOM L3 Core Second Edition so that it might be recorded
in that spec, an errata, or so that we can discuss.

Anne and I suggested an errata for this a few years back, but the
DOM folks were not receptive at the time, out of consideration for
http://lists.w3.org/Archives/Public/www-dom/2005OctDec/0011.html
http://lists.w3.org/Archives/Public/www-dom/2005OctDec/0025.html
See the thread for more discussion.
I also at the time raised another compatibility issue that I
http://lists.w3.org/Archives/Public/www-dom/2005OctDec/0024.html
The short version is that DOM forbids inserting nodes into a
different document than their ownerDocument, but browsers allow it
(in at least some cases).

Yup, this is a bad situation indeed. Basically browsers are stuck
with no good way out: Be compatible with the spec, or be compatible
with the web. Of course any serious web browser is going to choose
the latter.

The way out in this case is to fix the spec, in my opinion. Which
hopefully we will do. Fortunately, I think these two issues may be the
only two hard Web incompatibilities in all of DOM Core, which is not
bad compared to other specs from the same era.

- Maciej