How to track the event of closing a tab, and not switching to another one?

Question

JavaScript

There are 2 tabs of one site. It is necessary when closing one tab to transfer data to the second. I'm using the onbeforeunload event . But the problem is that if I just switch to another tab instead of closing it, onbeforeunload still fires.
How to track exactly the closing of the tab, I can not think of.

Answer 1

How to correctly track the tab close event?