If I get you correctly, you want to know when a tab/window is effectively closed.
(如果我正确地理解了您，您想知道何时有效关闭标签页/窗口。)
Well, AFAIK the only way in Javascript to detect that kind of stuffs are onunload & onbeforeunload events.(好吧，AFAIK是Javascript中检测此类内容的唯一方法是onunload和onbeforeunload事件。)
Unfortunately (or fortunately?), those events are also fired when you leave a site over a link or your browsers back button.
(不幸的是（或幸运的是？），当您通过link或浏览器的后退按钮离开站点时，也会触发这些事件。)
So this is the best answer I can give, I don't think you can natively detect a pure close in Javascript.(因此，这是我能给出的最佳答案，我认为您无法自然地在Javascript中检测到纯close 。)
Correct me if I'm wrong here.(如果我错了，请纠正我。)
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