Sometimes you just need a simple bit of code, but nobody has "just what you need". Here are some snippets I wrote when I ran into those cases. Maybe it'll help you out.
Caveat:
I'm assuming most everyone with a web browser can handle JavaScript - if not,
this stuff just doesn't work. I figure that for the vast minority of
browsers that can't handle JavaScript, it's not worth the coding effort to work
around. If you feel differently, well, good luck.