Body unload and asynchronous call

Hi there,



Is there a way to call a web method in the HTML body (onunload/onbeforeunload) event?



Something like:



window.onunload = BeforeLeave;

function BeforeLeave() {

var pa = { "param": "abcd"};

Sys.Net.WebServiceProxy.invoke(webServicePath, 'LeavePage', useHttpGet, pa, null, OnFailed, "", timeOut);

}



I've tried many different solutions but it just work if I put an alert() into it.



Thanks in advance,

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