如何阻止tag的window.on（'beforeUnload'）事件？

$(document).ready(function () {
$(‘#navigate’).on(‘mouseenter’, stopNavigate)
.on(‘mouseout’, function () {
$(window).on(‘beforeunload’, windowBeforeUnload);
});

});function stopNavigate(event) {    $(window).off('beforeunload');}function windowBeforeUnload() {    return 'Are you sure you want to leave?';}$(window).on('beforeunload', windowBeforeUnload);