onbeforeunload com mysql php

1<script type="text/javascript">
2window.onbeforeunload = function(){ 
3    var id = document.reset.id.value;
4    $.ajax({
5        url: "Resetter.php",
6        type: "GET",
7        data: {'id':id},
8        success: function (response) {
9            alert(response);
10        }
11    });
12}
13</script>