How to get the final URL after an Ajax redirect?

Question

I am working on an AJAX script that makes a GET request to a shortened URL, like a bit.ly link. How do I actually get the URL of the final/redirected page?

I can get the response headers from the redirected page, but it doesn't appear to contain the URL information:

$.ajax({
  url: "http://www.thislinkredirects.com",
  success: function(data, status, xhr) {
    var response = $(data);
  },
  complete: function(xhr) {
    console.log(xhr.getAllResponseHeaders());
  }
});

Result:

Date: Tue, 23 Jun 2015 03:22:07 GMT
Allow: POST, GET, OPTIONS, PUT, DELETE
Server: lighttpd/1.4.35
X-Powered-By: PHP/5.3.3
Transfer-Encoding: chunked
Access-Control-Allow-Methods: POST, GET, OPTIONS, PUT, DELETE
Content-type: text/html
Access-Control-Allow-Origin: *
Access-Control-Allow-Headers: accept, authorization

I do not have control of the server making the get request.

Answer 1

As I answered a similar question here: https://stackoverflow.com/a/48445360/1398908

A better solution is to supply jQuery's ajax with a custom xhr object like this:

var xhr = new XMLHttpRequest();

$.ajax({
    url: '/url',
    type: 'post',
    data: '...',
    xhr: function() {
         return xhr;
    }
});

Then you can access the current URL in any callback

success: function () {
    console.log(xhr.responseURL);
}

Note: IE doesn't support the responseURL property. (See docs)