Detecting that a jQuery.ajax call failed because the page is reloading?

Question

I do lots of $.ajax calls, and I handle errors from them in a way that throws up a message. I find that if an ajax call is in progress while the page gets reloaded, e.g. click

Answer 1

var unloading = false;
$.ajax(...) ...
 .error(function(jqXHR) {
    if (unloading) return; // Ignore errors caused by navigating away
    // Now, check for real errors ..
});
$(window).unload(function() {unloading = true;});

The above technique does not work for a periodically refreshing page (for example every half seconds). I have figured out that the error caused by refreshing the page can be avoided using delaying the error handling process by a small amount of time.

Example:

$.ajax(...)
.success(...)
.error(function(jqXHR) {
setTimeout(function() {
  // error showing process
}, 1000);
});

In addition to that

window.onbeforeunload = function() {//stop ajax calls}

event can be used for less frequently refreshing ajax calls.