Another example, since I've just had to deal with it: try and use "fadeIn()" and "fadeOut()" sometime when there's a transparent PNG somewhere in the affected content. There's no "fadedPngImagesLookTerrible()" predicate I can use. How do I decide what to do? Should I just back off from what I think to be a good design and get rid of my transparent PNG? Or should I instead just forego fading for the deficient browsers and allow people using ones that actually work to see the content the way I intended? The latter seems like a much better course of action, since no one user will suffer (well, the IE user suffers but they should be used to that :-) and I get to ship the design I intend. The only way I know of to code that is to explicitly detect the browser. (If jQuery were to include a "fadedPngImagesLookTerrible()" predicate, then that would at least hide the sniffing from my code, but I suspect that the library itself would have to sniff in order to provide the implementation.)
-- Turtle, turtle, on the ground, Pink and shiny, turn around.