BeforeUnload doesn't show Leave dialogue Box when Refresh Page and then Close Browser/Tab

I am working to show message (Leave Dialogue) when User close the Browser/Tab.

Until now, when I open the URL in the Browser and do some editing, and then close the Browser/Tab, the Leave Dialogue shows up.

The problem occurs, when I Refresh the page and then immediately close the Browser, the Leave Dialogue doesn't show up. I have debugged the BeforeUnload event, and the event is firing as well as the Return value, but still, the Leave Dialogue doesn't show in this scenario.

Here is my code:

window.addEventListener("beforeunload", function (e) {
         if (!anIsRefresh && IsViewMode() == false) {
            anIsRefresh = false;
            return e.returnValue = "";
            return "";
         }
      });

I am working on Asp.NET MVC.

Another thing: When I Reload/Refresh and then instead of closing Browser/Tab, click anywhere in DOM and then afterward close the Browser/Tab, the Leave Dialogue shows up. For this reason, I have tried to forcefully focus on the field whenever BeforeUnload is triggered but still, it doesn't work.