IE closure judgment and AJAX cancellation case study

<script language="javascript">
= function () {
var n = - ;
var b = n > - 20;
if (b && < 0 || ) {

try {
var xmlhttp = new ActiveXObject("");
("POST", "", false);
();
//return true;
}
catch (e) {
alert('delete user account error message:' + );
}

//return "Are you sure you want to exit the system? Please press 'Leave this page' to exit";
} else {
//alert("Refresh, not close");
}
}

</script>