jquery AJAX stopped working with iOS 5.0.1

Question

The following piece of logic used to work with both jquery 1.4.4 and 1.7.1 on all mobile devices that we're supporting:

$.ajax({
  url: 'http://www.example.com/someurl',
  type: 'GET',
  dataType: 'text',
  timeout: 60000,
  success: function(data) {
    alert(data);
  },
  error: function(jqXHR) {
    alert(jqXHR.state());
  }
});

But with iOS 5.0.1, the above enters the error function alerting rejected without any actual HTTP requests. It seems that exactly one AJAX request will work before I need to restart my iPhone. Is this a known jquery / iOS 5.0 problem? How can I debug it? Is there any workaround? I don't know where to start looking.

NOTE : I've noticed on the server side, that instead of GET requests, OPTIONS requests are issued. This seems to be a related issue:

http://spin.atomicobject.com/2012/01/20/mobile-safari-on-ios-5-1-unexpectedly-making-cross-origin-resource-sharing-requests/

Answer 1

The link that I provided in the question is actually pointing to the solution. Some of my ajax requests are used to fetch URL's of PDFs which are streamed using

Content-Disposition: attachment; filename="somename.pdf"

Apparently, that causes major issues in iOS 5.0's Safari, breaking the XMLHttpRequest object (it is not related with jquery). Crazy. Here's the link again:

http://spin.atomicobject.com/2012/01/20/mobile-safari-on-ios-5-1-unexpectedly-making-cross-origin-resource-sharing-requests/

Answer 2

Thank you for the investigation. I am having the same problem. After receiving a file as 'attachment' Mobile Safari sends OPTIONS request when calling:

$.ajax('/url')

BUT, if I run the following code from the same file, it generates a valid GET request:

http = new XMLHttpRequest()     
http.open("GET", "/url")
http.send()

Why jQuery is not working but XMLHttpRequest works here?

Answer 3

The reason for the error is the same origin policy. It only allows you to do XMLHTTPRequests to your own domain. See if you can use JSON instead.

References and recommended resources;
https://stackoverflow.com/a/1109261/896341
http://api.jquery.com/jQuery.getJSON/
http://www.w3.org/Security/wiki/Same_Origin_Policy
https://developer.mozilla.org/En/Same_origin_policy_for_JavaScript