OctaneZ's Journal: Need some javascript help

Okay, I need some web help! Googling for javascript help yields tens of thousands of seemingly unhelpful tutorials and guides. I have a webform with 3 select boxes:

[Select #1] [Select #2] [Select #3]

I would like to "chain" the boxes, such that values for boxes #2 and #3 are selected based on the value of the option selected in box #1; for those curious the first box is the maximum depth the Spray glider should dive to, the second box, is the maximum glide time, and the third field is the number of points it should average when telemetering data back to shore. I've tried a b8unch of onChange's; and tried hard to make selectedIndex work, but there must be someway that uses the value of the option rather than it's place in the index right? There are a couple hundred options in the menus. Any ideas?

I'll take a stab at it

[StalinsNotDead]

It's not going to be exactly right (I'm a bit rusty), but it might help you out some.

tar is the list box which is going to be changed
appropriateValue is the the value which needs to be selected in tar

Here's a loop that uses the values of the options in a drop down list as a comparison and assigns selected Index of the last matching value.

var selIndex = -1;
for(var i = 0; i tar.length; i++)
{
if(tar.options[i].value == appropriateValue)
{
selIndex = i;
}
}
tar.selectedIndex = selIndex;

Hope this is somewhat helpful.