window.onbeforeunload not working on the iPad?
This bit of JavaScript works for me on Safari and Chrome on ipad and iphone, as well as desktop/laptop/other browsers:
var isOnIOS = navigator.userAgent.match(/iPad/i)|| navigator.userAgent.match(/iPhone/i);
var eventName = isOnIOS ? "pagehide" : "beforeunload";
window.addEventListener(eventName, function (event) {
window.event.cancelBubble = true; // Don't know if this works on iOS but it might!
...
} );
I have found that the onunload() event does fire. It's behavior is somewhat odd; whatever you have in your callback function attached to the event is actually run after the new page has loaded in the background (You can't tell it's loaded yet, but server logging will show that it has).
More oddly, if you have a confirm() call in your onunload(), and the user has clicked a link to go somewhere else, you are in business. If, however, the user closes the iPad Safari browser tab, the onunload() event will fire, but your confirm() will have an implicit cancel as response.
Only Apple would know for sure, but my guess is that they purposely did not enable that functionality in mobile Safari because it is most often used by shady characters to get you to stay on their site or pop up lots of porn/advertising windows.
There's a known bug in WebKit with onbeforeunload. I believe it's fixed in the latest beta of Chrome 5, but it's quite possible the iPad's browser is made from a version of WebKit that doesn't have the fix.
Related Chrome bug report.
beforeunload event is not supported by Mobile Safari. You can see the list of all supported events here: Handling Events Apple documentation
And the beforeunload is not in the list!