[SalesForce] Error handling from JS remoting

We are using JS remoting. Found this interesting race condition:

1. JS Remoting AJAX request made by user.
2. Before it completes the user moves to another page
3. When user moves browser to another page the js remoting ajax request is aborted.
4. The abort invokes the error handler and we have a generic error handler which pops up a dialog showing exception info.
5. In some cases, the dialog will flash up for a second because the page navigation away hasn't completed.

This looks ugly and we would prefer if the error handler knew there was a page unload happening and not show the error dialog if this was happening.

So, I tried adding a page unload listener and setting a flag in that which can be subsequently checked.

jQuery(window).unload(function() {
    unloadhappening = true;
});

This approach will work in most ajax designs but won't with JS remoting. JS remoting, calls the error handler before the unload event. Not sure why?

I tried the earlier beforeunload event:

jQuery(window).on('beforeunload', function() {
    unloadhappening = true;
    return '';  
}); 

This won't work because this event just shows up another dialog.

So I tried to add a listener to all anchor tags that have a http(s) hyperlink

jQuery('a[href^=http]').click( function() {
    unloadhappening = true; 
})

This won't work for relative URLs.

So I tried to adding a listener to all anchor tags that have a href

jQuery('a[href]').click( function() {
    unloadhappening = true; 
})

This will filter out components that won't work because it won't filter out components that don't trigger a page unload such as:

   <a href="#adviceTab">Advice</a>

So before I go and write a selector to filter out anything with a fragment identifier, there are also some anchors that are coming form JQuery UI that do:

   <a href="javascript:%20void%280%29%3B" class="calToday"    onclick="DatePicker.datePicker.selectDate('today');return false;">Today</a>

I am starting to think this is a more of a hack that will never work as opposed to a solution. Do you have a good idea for this problem?

The only idea I can think of is to check the exception, error, event info returned by
JS remoting for an aborted request. I see: Strings:

Unable to connect with Server 

and

Communication Failure

But that error message is also used when a JS remoting ajax request is aborted because of network failure in the middle of an ajax request – not just because it is aborted because of navigation to another page. If you want different error handling for the two it is impossible to differentiate between them.

Note I have to use JS Remoting here. Using forceTK etc is not an option. So I am wondering has anyone else seen this and if so what is your solution?

Thanks