With
$(window).unload()
you’d be able to confirm the results of the ajax call, like handle returned data on a call back function and I guess the page would have gone away by then.
If you need some sort of confirmation that the ajax call was successful, or to handle returned data, look for a way to do it before unload.
Use this,
window.onbeforeunload = function (e) {
}
-KR