Fragmentation of the installed base of browsers will only get worse. By definition, it can never improve
unless absolutely everyone on the planet threw away their old browsers and upgraded to the latest geewhiz
versions. But even then, there are plenty of discrepancies between the scriptability of the latest
Netscape Navigator and Microsoft Internet Explorer.
The situation makes scripting a challenge, especially for newcomers who may not be aware of the
limitations of earlier browsers. A lot of effort in my books and ancillary material goes toward helping
scripters know what features work in which browsers and how to either workaround limitations in
earlier browsers or raise the compatibility common denominator.
Designing scripts for a Web site requires making some hard decisions about if, when, and how to
implement the advantages scripting offers a page to your audience. For public Web sites, I recommend
using scripting in an additive way: let sufficient content stand on its own, but let scriptable browser
users receive an enhanced experience, preferably with the same HTML document