var ref = window.open('http://google.com', '_blank', 'location=yes');
ref.addEventListener('loadstart', function(event) { alert('start: ' + event.url); });
ref.addEventListener('loadstop', function(event) { alert('stop: ' + event.url); });
ref.addEventListener('exit', function(event) { alert(event.type); });
The callback function is called when the event is fired. The function is passed an InAppBrowserEvent object.