c# - calling web method on window onbeforeunload event -

i working on basic asp.net website , want execute server side function when user try go away page. using onbeforeunload event of window. have check box on page , when user checked check box, executing sverside "checkedchange event". issue whenever user click on check box web method called, should not called postback happen, user not leaving page. can 1 suggest me avoid web method call when postback happen. wnat execute web method in following scenarios: 1) when user closes browser. 2) on click of “find more matches” button, when user landed on search results page no school listed. 3) when user changes url browser's address bar

code on aspx page:

     function getmessage() {          var urlstring = document.url;          {               pagemethods.message( document.url);          }      }  </script>     code on aspx.cs page   [system.web.services.webmethod] public static void message() {     string x="a"; } 

this link should hold answer looking for: how capture browser window close event?

i think following code link looking for.

var informorlink; $('a').live('click', function() { informorlink = true; }); $('form').bind('submit', function() { informorlink = true; });  $(window).bind('beforeunload', function(eventobject) {     var returnvalue = undefined;     if (! informorlink) {        //todo: execute code before unload here        //returnvalue = "message display before user leaves page.";     }     eventobject.returnvalue = returnvalue;     return returnvalue; });