How to get notification when window closes in Firefox extension?
You can use "window.onbeforeunload" event.
Here is the reference page: https://developer.mozilla.org/en-US/docs/Web/API/WindowEventHandlers/onbeforeunload
You can use "window.onbeforeunload" event.
Here is the reference page: https://developer.mozilla.org/en-US/docs/Web/API/WindowEventHandlers/onbeforeunload