function CallMe(src,dest)
 {    
     var ctrl = document.getElementById(src);
     // call server side method
     PageMethods.Email_TextChanged(ctrl.value, CallSuccess, CallFailed, dest);
 }
 
 // set the destination textbox value with the ContactName
 function CallSuccess(res, destCtrl)
 {    
     var dest = document.getElementById(destCtrl);
     dest.value = res;
 }
 
 // alert message on failur
 function CallFailed(res, destCtrl)
 {
     alert(res.get_message());
 }
 

 // call server side function from client side
function CallServerSideFunction1()
{
    //calling our page method
    PageMethods.Search(OnSucceeded1, OnFailed1);
}

function OnSucceeded1(result)
{
     var zip = $get("txtZip");
     zip.value = result;
}

function OnFailed1(error)
{
   // Alert user to the error.
   alert(error.get_message());
}