Alternitavely look
here[
^]
Basically you use JQuery to call a (static) webmethod defined in an aspx page.
There are some articles around so search google and come back with questions if you get stuck.
If you don't know JQuery look
here[
^]
Whatever you do, I feel that calling server side code from client is still more like hacking or a workaround than an actual solution. If you can avoid this by redesigning, do so.
hope this helps.