【原创】javascript 关闭窗口前提示

<script src="scripts/jquery-1.4.1.js" type="text/javascript"></script>
<script type="text/javascript">
$(
function () {
$.post("Handler.ashx", {}, function (data) {
datafrom = data;
});
}
);

window.onbeforeunload = beforeUnload;
window.onunload = unload;

var datafrom = "";
var gotobaidu = false;
function beforeUnload() {

if (confirm(datafrom)) {
}
else {
window.location.href = "http://www.baidu.com";
}
}
function unload() {

}
</script>