How do you apply the javascript pop-up code to a formula button that already contains a formula?

I have the code for the pop-up:
"javascript: alert ('This vehicle is currently listed in another location ')"

And here is my formula to show that the box is checked if the vehicle is in this location. There are about 7 more locations as well, but if someone tries to click on this button, and a checkbox is selected somewhere else on the page, I want the message to pop up.


var text URL = URLRoot() & "db/" & Dbid() &   "?act=API_EditRecord&rid=" &ToText([Record ID#])
& "&_fid_44=" & ([Recon - IN]="I")& "&_fid_88=1";

"javascript:" &
"$.get('" &
$URL &
"',function(){" &
"location.reload(true);" &
"});" & "void(0);