Ever run into things that are more complicated that you orginally expected?  Of course, we all do -- all the time. So I shouldn't have been surprised why Javascript/DHTML (dynamic HTML) has gotten more complicated rather less complicated with time.  The pure technology has probably gotten better -- but figuring out what's going on seems more difficult.

Last Friday, I sat down to run a demo for handling a simple slideshow from O'Reilly's Javascript Application Cookbook.  The demo works in IE 6.0 and Netscape Navigator 4.79 but didn't work at all on Netscape 6.2 or Mozilla 1.1.  Hmmm, I wondered -- why would later versions of Netscape fail to handle something that the older versions did?  With a bit of digging around, I came across Transitioning from Proprietary DOMs and Markup to W3C Standards: Enhancing Pages That Use LAYER, document.layers[], and document.all to Support Standards:

Greetings! If you've been referred to this page, it's probably because your site has a web page that depends on one of the following proprietary Navigator 4 or Internet Explorer 4/5 features:
 

Proprietary Nav4 Features	Proprietary IE4/5 Features
document.layers[], document.elementName, and other Nav4 Layer DOM features	document.all and other IE4/5 DOM features
document.tags, document.ids, document.classes, or document.contextual() for setting CSS properties from Nav4 JavaScript	document.styleSheets[] for setting CSS properties from Internet Explorer JScript
LAYER, ILAYER, and MULTICOL elements	MARQUEE and BGSOUND elements
DIV SRC= transclusions (external content imported into an HTML page using <DIV SRC=...)
use of .jar files for SmartUpdate	.cab files

These features of Navigator 4 and Internet Explorer 4/5 Dynamic HTML were not adopted by the W3C HTML 4.0 or Document Object Model specifications, so they are not supported in new Mozilla-based browsers such as Netscape 6 that are built on W3C standards. [emphasis mine] This page summarizes how to enhance pages that use these proprietary features so that they are fully W3C-compliant and will display on all compliant browsers (such as Netscape 6, Mozilla, Customzilla, etc.) and devices (such as consumer browsing appliances that embed the Gecko layout engine).

I know that this is old news for anyone who has been doing serious DHTML -- but it was a bit of a rude awakening for me. So, for the sake of moving ahead to do the "right thing" (implement the W3C DOM), the writers of Netscape 6+ and Mozilla decided to throw out backwards compatability with Netscape 4.x.   I understand why they chose to do that -- but it certainly caught me a bit off-guard.  It also leaves me the task of figuring out whether I would have to write DHTML that handles non-Javascript browser, low-end Javascript browsers, NN 4.x, IE and the new W3C DOM compliant browsers!!  It seem like a lot of work to do....Anyone have a good experience with the cross-browser DHTML APIs as a way of addressing this problem?

[Later today:  David points out the DOM Inspector in Mozilla/Netscape -- thanks.  It's good to hear that I'm not the only one who finds Javascript/DHTML to be a complicated mess and wonders about its large-scale usefulness.]