How to submit forms with 3 variables

Pardon me for re-submitting this question, but the original seems to be so
far down the list by now that I don't think anyone else will see it.

I'm trying to create a client-side function that brings up a specific
response to a combination of 3 variables selected by the user through form
objects (2 select lists and one radio-button set)

For instance, the user could select a color from one list, a size from
another, and a style from the third. On submit, the page would return a text
field specific to their selection (a description the model number, specs and
price, etc.).

Is there a "simple" java script known that would accomplish this? It doesn't
seem hard, but I can't find a clue anywhere on how to write this.