window.onbeforeunload = onbeforeunload_handler; function onbeforeunload_handler(){window.location.href = "./Product"; var warning="確認退出sssssssssss?"; return warning;}window.attachEvent("onbeforeunload",onbeforeunload_handler());總是報錯說window.attachEvent不是一個函數(shù)并且頁面空白 是什么情況呢