A while ago in one of my projects I came into this problem that I wanted to detect when a child window that is created with window.open method gets closed.

As you know it is possible to call a JavaScript function in parent page from a popup window using parent.[JavaScript-Method-Name]. But this didn't work for me because the page I was opening was from another domain and couldn't modify its content.

Unfortunately the popup window does not have any close event that you can listen to but there is a closed property that is true when window gets closed. So the solution I came up with was to start a timer and check the closed property of the child window every second and clear the timer when the window gets closed. Here is the code:

var win = window.open('http://www.google.com', 'google','width=800,height=600,status=0,toolbar=0'); 
var timer = setInterval(function() { 
    if(win.closed) {
        clearInterval(timer);
        alert('closed');
    }
}, 1000);

Hope this helps.