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如何使用jQuery检测浏览器是否已关闭(How to detect if browser is closed using jQuery)

 我需要检测浏览器是否正在使用jQuery关闭，并且如果这是真的则执行一个事件。 我在我的网站上有一个聊天功能（很像Facebook），当用户导航到网站结构中的其他页面时，会保持用户登录，但是如果他们点击，则需要将他们从聊天中记录下来（因此他们不会在线显示给他人）浏览器关闭按钮。 因此.unload()将无法工作，因为.unload（）会将注销功能应用于所有窗口操作，包括导航到网站结构中的另一个页面。 .unload()适用于浏览器关闭，但也适用于浏览器前进和后退导航，因此我需要一种方法来检测浏览器是否正在关闭，并且仅在浏览器关闭时。 

I need to detect if the browser is being closed using jQuery, and do an event if this is true. I have a chat feature on my website (much like Facebook) that keeps the user logged in as they navigate to other pages within the website structure but needs to log them out of chat (so they do not appear online to others) if they click the browsers close button. So .unload() will not work because .unload() will apply the logout function to all window actions including navigating to another page within the website structure. .unload() works for browser closes, but also works for browser forward and backward navigation, so I need a way to detect if the browser is being closed AND ONLY if the browser if being closed.

原文：https://stackoverflow.com/questions/4096955

更新时间：2023-11-01 12:11

最满意答案

 您可以将'a'转换为'factor'并在执行table之前指定levels  
table(factor(a, levels=seq_len(max(a))))
#1 2 3 4 
#0 3 3 1 
 
 如果您需要也应指定自定义level 。 使用评论中的示例，  
a<- c(2,3,3,3,2,2)
table(factor(a, levels=1:4))
#1 2 3 4 
#0 3 3 0 

You can convert 'a' to 'factor' and specify the levels before doing the table 
table(factor(a, levels=seq_len(max(a))))
#1 2 3 4 
#0 3 3 1 
 
If you need a custom level that should be specified as well. Using the example from the comments, 
a<- c(2,3,3,3,2,2)
table(factor(a, levels=1:4))
#1 2 3 4 
#0 3 3 0

如何使用jQuery检测浏览器是否已关闭(How to detect if browser is closed using jQuery)

最满意答案

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