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Re: "getElementsByTagName" and namespaces

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Stefan Ram wrote:

>   The DOM4 specification of the W3C says:
> 
>       »The getElementsByTagName(localName) method must return
>       the list of elements with local name localName for the
>       context object. Note: Thus, in an HTML document,
>       document.getElementsByTagName("FOO") will match FOO
>       elements that are not in the HTML namespace, and foo
>       elements that are in the HTML namespace, but not FOO
>       elements that are in the HTML namespace.«
> 
>   So, why will the uppercase argument »FOO« match
>   lowercase names from the HTML namespace but not
>   uppercase names from it?

Again you should have cited your reference and given the URI of the quoted 
specification, <http://www.w3.org/TR/2015/REC-dom-20151119/#dom-document-getelementsbytagname>.

Why getElementsByTagName() is supposed to work this way is explained in the 
part that the link with text “list of elements with local name /localName/” 
refers to:

,-<http://www.w3.org/TR/2015/REC-dom-20151119/#concept-getelementsbytagname>
| 
| The list of elements with local name /localName/ for a node /root/ is the 
| `HTMLCollection` returned by the following algorithm:
| 
| 1. If /localName/ is "*" (U+002A), return a `HTMLCollection` rooted at 
|    /root/, whose filter matches only elements.
| 
| 2. Otherwise, if /root/'s node document is an HTML document, return a 
|    `HTMLCollection` rooted at /root/, whose filter matches the following 
|    descendant elements:
| 
|    * Whose namespace is the HTML namespace and whose local name is 
|      /localName/ converted to ASCII lowercase.
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

That excludes “FOO” elements *in the HTML namespace* with 
getElementsByTagName("FOO"), and leaves only “foo” elements *in that 
namespace*.

|    * Whose namespace is not the HTML namespace and whose local name is 
|      /localName/.
       ^^^^^^^^^^^

That includes “FOO” elements *not in the HTML namespace* with 
getElementsByTagName("FOO").
 
| 3. Otherwise, return a `HTMLCollection` rooted at /root/, whose filter 
|    matches descendant elements whose local name is /localName/.

> [troll bait]

Nice try.

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Re: "getElementsByTagName" and namespaces Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-04 22:45 +0100

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