Hixie's Natural Log: The DOM0 Legacy: HTMLOptionsElement

2006-10-16 23:52 UTC The DOM0 Legacy: HTMLOptionsElement

I'm trying to spec DOM5 HTML, a part of the same specification as HTML5/XHTML5. Specifically, today I'm trying to specify the various collection interfaces, and in particular, I'm trying to specify HTMLOptionsCollection.

The DOM2 HTML spec's take on the matter is somewhat far from the truth.

Here are some amusing tidbits I've found so far:

In IE7, the select element is the same as its options collection. Literally, it's the same object. (Demo)
In IE7, the namedItem() method of the HTMLOptionsCollection/HTMLSelectElement object is not equivalent to indexing into the object using the JavaScript square-bracket notation. (Demo)
In Opera9, HTMLOptionElements have a length property that returns the number of option elements in their select element. I can't find any reason for this attribute's existence. No other browser does this. (Demo)
In Webkit trunk and IE7, if multiple elements match the argument to HTMLSelectElement.options.namedItem(), then a list is returned, much like when (in any browser) multiple nodes match HTMLFormElement.elements.namedItem(). In Firefox trunk and Opera9, only a single element is returned, not a list, much like when (in any browser) multiple nodes match HTMLDocument.images.namedItem(). (The fact that HTMLFormElement.elements and HTMLDocument.images are both, according to the DOM2 HTML spec, supposed to be HTMLCollection objects with the exact same behaviour is, of course, neither here nor there.) (Demo)
In Webkit trunk and Firefox trunk, id and name attributes on option elements are considered equals when it comes to matching for namedItem(). In Opera9 and IE7, only the id attribute is examined, the name attribute is ignored. (Demo)
In Webkit trunk, setting the length property to a smaller value doesn't remove children of optgroup elements. (Demo)
In IE7, setting the length property to a greater value adds new nodes to the last optgroup element of the select, if there are no option nodes after it. (Otherwise, it does like other browsers, and append them to the select.) (Demo)

The spec is going to be a mix of all of the above, so none of the browsers are going to exactly match it.