[jQuery] how to do error handling in ajax

[jQuery] how to do error handling in ajax


Hi Jquery guys,
I am using below syntax for ajax error handling, but I never got any
specific error details. its always undefined.
function Error(xhr, ajaxOptions, thrownError)
{
// dump is javascript dump
    dump(xhr, true);
    dump(ajaxOptions, true);
    dump(thrownError, true);
}
pls suggest what to do.
note: for dump:
http://www.netgrow.com.au/files/javascript_dump.cfm