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Re: [DOMCore] createElement() and HTML-specific element interfaces

From: David Flanagan <dflanagan@mozilla.com>
Date: Tue, 09 Aug 2011 11:52:51 -0700
Message-ID: <4E418203.9050903@mozilla.com>
To: Ms2ger <ms2ger@gmail.com>
CC: www-dom@w3.org
On 8/9/11 9:20 AM, Ms2ger wrote:
> Hi David,
>
> On 08/09/2011 05:56 PM, David Flanagan wrote:
>> I can't see anything in the DOMCore spec that references the fact that
>> HTML defines lots of Element subclasses and that createElement('table'),
>> for example, is supposed to return an instance of HTMLTableElement.
>>
>> Also, it is unclear to me what should happen if d is a document returned
>> by createDocument (not createHTMLDocument) and I call
>> d.createElement("table"). The spec is clear that the element will use
>> the HTML namespace, but it is not clear whether the resulting object is
>> instanceof HTMLTableElement or just Element.
>>
>> createElementNS() is similarly underspecified: under what circumstances
>> does it create instances of the HTML-specific interfaces defined in the
>> HTML spec?
>
> Indeed, this is left up to the HTML specification. It defines [1] that 
> elements must implement the interface listed in the definition box, 
> which is HTMLTableElement for table elements [2].

Thanks; I had not found that paragraph of the HTML spec.  I'd say that 
it would be worth adding a note to the DOM spec mentioning that HTML 
imposes these additional requirements...

But more to the point, the DOM spec also needs to say when those 
additional HTML requirements apply.  If I create a "table" element in 
each of these scenarios, in which of them to do I get an HTMLTableElement?

1) html document, createElement
2) non-html document, createElement
3) html document, createElementNS, HTML namespace
4) html document, createElementNS, non-HTML namespace
5) non-html document, createElementNS, HTML namespace
6) non-html document, createElementNS, non-HTML namespace

It seems clear to me that 1 & 3 should result in an HTMLTableElement, 
but I honestly don't know about the other cases.  And I think that the 
DOM spec needs to define this.

There is a similar situation for DOMImplementation.createDocument() and 
DOMImplementation.createHTMLDocument().  The DOM spec should note that 
the HTML spec imposes additional requirements on the object reaturned by 
createHTMLDocument().  (i.e. that it must implement the HTMLDocument 
interface).  And I think that the DOM spec also needs to normatively 
state whether the object returned by createDocument() implements 
HTMLDocument or not.  The HTML spec says that it does, but since HTML 
depends on DOM and not the other way around, it seems to me that the DOM 
spec needs to say something about this.

Note that since DOM already defines a flag that creates a distinction 
between HTML documents and XML documents.  It will be very confusing if 
createDocument() returns an "XML document" that implements the methods 
of HTMLDocument!

     David



>
> HTH
> Ms2ger
>
> [1] http://www.whatwg.org/html/#element-definitions
> [2] http://www.whatwg.org/html/#the-table-element
Received on Tuesday, 9 August 2011 18:53:29 GMT

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