onBeforeUnload处理程序在IE中表示null [英] onBeforeUnload handler says null in IE

问题描述

我的网络应用有这个：

$(window).bind('beforeunload', function() {
    if(unSavedChanges == true)
    {
        return 'You have unsaved changes';
    }
    return null;
});

这在Safari和Firefox中运行良好（除了firefox没有显示我的自定义消息） onBeforeUnload对话框）。但是在Windows 7上的IE 8上，它总是显示onBeforeUnload通知，特别是如果没有未保存的更改，它只会说null。当用户保存了所有内容并希望离开时，如何阻止IE显示onBeforeUnload通知？

this works fine in Safari and Firefox (with the exception that firefox does not show my custom message in it's onBeforeUnload dialog). However on IE 8 on Windows 7, it always shows the onBeforeUnload notification, specifically if there are no unsaved changes, it would just say "null". How can I prevent IE from showing onBeforeUnload notification when user has saved everything and wants to navigate away?

根据Jon的建议，我删除了返回null 行，代码现在读取

as per Jon's suggestion, I have removed the return null line, the code now reads

$(window).bind('beforeunload', function() {
   if(unSavedChanges == true)
   {
       return 'You have unsaved changes';
   }
});

推荐答案

删除 return null 行，它应该没问题（在Javascript null 和 undefined 是不同的东西）。

Remove the return null line and it should be fine (in Javascript null and undefined are different things).

顺便说一下， MDN 表示为了获得最大兼容性，您应该接受事件参数并设置 event.returnValue 。

By the way, MDN says that for maximum compatibility you should be accepting an event parameter and setting event.returnValue as well.

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