Using mapped image to fill a text box in a form

[canuck]

I'm new to php and javascript. I'm working on a form that have 3 sets of checkbox and a text box. When a user clicks on the checkbox a popup window of mapped image comes out. The image is a map. When the user clicks on a certain city, the text box get's filled with whatever city the user clicks and then closes. So far, this is the part that I get stucked. I can make it work when the map and the form are on the same page using the code below that I found online:\[code\]<AREA SHAPE='POLY' COORDS="340, 675, 340, 676, 335, 694, 339, 698, 348, 709, 332, 737, 334, 737, 336, 749," HREF="javascript:void(0);" onClick="document.forms['Form1'].Field1.value ='http://stackoverflow.com/questions/3791797/Honolulu'; return false;">\[/code\].....but I'm having problem when these two are on a different page. The solution that I could think of is using javascript variable and send it to the form from the image map. Sounds possible but couldn't figure out how to pass the same variable to the different page.Is there any other way to do this?Thanks in advance!