asp.Net Webページを閉じる前にjsイベントクリアクッキーをトリガー

 1  window.onbeforeunload = function () {
 2             delCookie("CookieName");
 3         }
 4         //  cookies
 5         function delCookie(name) {
 6             var exp = new Date();
 7             exp.setTime(exp.getTime() - 1);
 8             var cval = getCookie(name);
 9             if (cval != null)
10                 document.cookie = name + "=" + cval + ";expires=" + exp.toGMTString();
11         }
12 
13         function getCookie(name) {
14             var arr, reg = new RegExp("(^| )" + name + "=([^;]*)(;|$)");
15             if (arr = document.cookie.match(reg))
16                 return (arr[2]);
17             else
18                 return null;
19         }