document[id] and document.id to <element id="id"> matching

Note1: Testing in IE8 final, Firefox latest trunk, Safari 4 with latest webkit nightly and the latest Opera 10 snapshot <http://my.opera.com/desktopteam/blog/2009/04/03/turbo-in-10> (and <http://labs.opera.com/news/2008/11/25/> for <video>)

Note2: This is specifically about document.id to @id matching and not window.foo to @id/@name or document.name to @name matching.

IE, Firefox, Safari and Opera seem to differ on how they match document.id to <element id="id">.

The main differences between browsers are:

1. What elements are named elements (object, applet etc.)

2. When #1 is matched. <element id="id"> and or <element id="id" name=""> and or <element id="id" name="non-empty">

With that said, attached is an example that shows when and how applet, object, embed, iframe, img, form, canvas and video come up as matches in different browsers. I haven't found any other elements that are matched in browsers (keeping note #2 in mind), so other elements are not in the test.

These are the results of the test:

Opera:
OBJECT with no @name
APPLET with no @name
EMBED with no @name
IFRAME (as Window object) with no @name
IMG with no @name
OBJECT with empty @name
APPLET with empty @name
EMBED with empty @name
IFRAME (as Window object) with empty @name
IMG with empty @name
OBJECT with non-empty @name
APPLET with non-empty @name
EMBED with non-empty @name
IFRAME (as Window object) with non-empty @name
IMG with non-empty @name
FORM with non-empty @name
CANVAS with no @name
CANVAS with empty @name
CANVAS with non-empty @name
VIDEO with no @name
VIDEO with empty @name
VIDEO with non-empty @name

Firefox:
OBJECT with no @name
APPLET with no @name
EMBED with no @name
IMG with no @name
OBJECT with empty @name
APPLET with empty @name
EMBED with empty @name
IMG with empty @name
OBJECT with non-empty @name
APPLET with non-empty @name
EMBED with non-empty @name
IMG with non-empty @name

Safari:
OBJECT with no @name
APPLET with no @name
OBJECT with empty @name
APPLET with empty @name
IMG with empty @name
OBJECT with non-empty @name
APPLET with non-empty @name
IMG with non-empty @name

IE:
OBJECT with no @name
APPLET with no @name
OBJECT with empty @name
APPLET with empty @name
OBJECT with non-empty @name
APPLET with non-empty @name
EMBED with non-empty @name
IFRAME (as Window object) with non-empty @name
IMG with non-empty @name
FORM with non-empty @name

(I only tested fallback-free objects though)

Now, HTML5 covers this at <http://www.whatwg.org/specs/web-apps/current-work/multipage/dom.html#dom-document-nameditem>.

However:

1. I don't really understand the part about there always being one element by definition and 'lists' and collections in this case. I don't really understand the first iframe case either.

In other words, if I had to create a JS function to show an example of how the spec says the matching works, I couldn't do it given the current text in the spec.

Perhaps if it was more like "Let x be the result of" etc. like the parsing steps are.

2. I'm not sure when exactly it says to match iframe in these cases.

3. I'm not sure if the named element conditions are as compatible as they could be. Specifically, <img> matching in the spec is compatible with Safari more than it is Opera, Firefox and kind of IE.

4. Opera seems to do more iframe matching than any others in these cases, which it looks like it should stop doing. But, is the spec following IE here or something different? I can't tell for sure and, Firefox and Safari don't match iframes at all in these cases.

FYI though: opera matching for <iframe id="test"> (IFRAME (as Window object) with no @name) seems to be a compatibility problem with at least some pages on at least one Wifi AP.

5. Opera matches <canvas> and <video> in these cases. Not sure about <canvas>, but matching for <video> in this case *might* make sense to be consistent with <object> and <embed>. Then again, there's probably no reason to add more chaos when Safari and Firefox don't currently do it. Have <video> and <canvas> been considered? What about <audio>?

No with that said, that's just a review of document.id to @id. I'm not sure how good the spec does @name matching. Haven't tested that.

-- 
Michael