Catching 403 from $.ajax promise in jQuery v1.x

Question

I'm having problems with catching 403 from $.ajax promise in jQuery v1.x.

The same code

$.ajax({
    dataType: 'jsonp',
    url: 'http://www.checkupdown.com/accounts/grpb/B1394343/',
    type: 'GET'
}).then(function () {
    console.log('success', arguments)
}, function () {
    console.log('error', arguments)
});

rejects the promise as expected in jQuery v2.x but logs nothing in jQuery v1.x (the promise has readyState == 1).

The examples use 2.1.3 and 1.11.3 jQuery versions respectively.

Why exactly does this happen? Is it solvable for jQuery v1?

Answer 1

It's tricky because you're not making a real AJAX request. JSON-P is a hack, and will cause all sorts of problems for you.

If you really want to detect errors reliably, you need to use a real AJAX request.

Answer 2

They perform differently because in 1.11.x, an error event handler is not attached to the script tag, instead all you have is an onload or onreadystatechange handler.

https://github.com/jquery/jquery/blob/1.11.3/src/ajax/script.js#L57

https://github.com/jquery/jquery/blob/2.1.3/src/ajax/script.js#L44

There is no workaround other than using a timeout or performing the jsonp request yourself.