Here are some links about the W3C DOM and its implementation in the Version 5 browsers.
W3C DOM Level 1 Specification. The official description of how the DOM ought to work.
Microsoft XML DOM Reference, unfortunately the link is dead now. I haven't been able to find its new location.
The Microsoft way of implementing the DOM. This reference
is mainly focused on VBScript, but most methods and properties also work in JavaScript.
Gecko DOM Ref. Unfortunately this reference is not very useful. Although it gives a good overview of the W3C DOM in rather simpler language than W3C itself, it doesn't give any compatibility information at all. This reference is a wish list of what Mozilla should eventually support, but is worthless for determining current Mozilla support.
Opera DOM support. Details about what Opera is supposed to support.
kHTML Class Index. Konqueror documentation on JavaScript. Unfortunately it's in extremely technical language, so that it's not easy to find out how something is supposed to work, certainly not for the average web developer (which includes myself). Nonetheless it's good to have some documentation.
iCab InScript. iCab calls JavaScript 'InScript'. This reference
gives information about what iCab supports. I'm not sure why this information is on the Muchsoft site and
not on the iCab site.
"The Document Object Model (DOM) is still missing some parts. Especially many W3C-DOM level 1 standard objects are still missing."
What shall we do with the W3C DOM?
Forms, usability and the W3C DOM
DOM1 Reference. A translation of the W3C Spec to slightly more normal language. Includes some coding examples in JavaScript.
XUL Tutorial. I’m not yet sure how XUL works, but it's supported only by Mozilla and is meant to define the user interface. This tutorial includes some interesting proprietary CSS extensions.
Ryan's DHTML Tutorial. Despite the title this excellent tutorial treats all JavaScript DOMs in existence,
from simple Level 0 form functionality to sophisticated W3C DOM event handling. Better still, it's targeted at newbie scripters,
explains all necessary details (but no more) in easy steps and always pays attention to browser compatibility.
Definitely the place to go if you're new to programming and want to understand the JavaScript DOMs.
J. David Eisenberg's excellent series of articles in A List Apart:
Meet the DOM: About the DOM in general
and the differences with the earlier browser specific DOMs.
DOM Design Tricks 1: About the display
style declaration.
DOM Design Tricks 2: About event capturing in
Netscape 6.
DOM Design Tricks 3: About the changing of texts
in a document. About nodes.
Examples.
The very first page that treated aspects of the W3C DOM. I myself took the document.getElementById
syntax from this page way back in 1999.
Doctype checker. Very useful page in which you can select a doctype and see whether your browser renders the page in strict or legacy mode.
International Herald Tribune. The first mainstream site I know of with a beautiful DOM implementation. Go to any article and try the icons in the lower right corner.
DOM 2 Range with JavaScript. Tutorial for the Range API. Works only in Mozilla.
Mozilla - Traversing a Table. Example script that messes about with a table. Useful for getting the hang of DOM scripts.
PBWizard. Interesting examples and articles about the W3C DOM and related standards. Some nice scripts and there's more to come.
For JavaScript links, see the JavaScript links page.
For CSS links, see the CSS2 links page.