Javascript Question

I need to know where to get a code for my webpage.
This is what exactly I am trying to get done.
I want to have people coming to my sight use a form to put in their city and have some javascript
then send them to the webpage that matches their city.

Example They select Issaquah, WA
The code sees Issaquah as King County and
sends them to a webpage sepcifically for
King County.

I know this can’t be too difficult code wise
the hard part will be doing what city goes
to where for thearea.

Can anyone lead me to a place where I can
pick up this kind of code?????

Thanks