IE9 jQuery AJAX with CORS returns "Access is denied"

Question

The following works in all browsers except IE (I'm testing in IE 9).

jQuery.support.cors = true;
...
        $.ajax(
            url + "messages/postMessageReadByPersonEmail",
            {
                crossDomain: true,
                data: {
                    messageId       : messageId,
                    personEmail     : personEmail
                },
                success: function() {
                    alert('marked as read');
                },
                error: function(a,b,c) {
                    alert('failed');
                },
                type: 'post'
            }
        );

I have another function which uses dataType: 'jsonp', but I don't need any data returned on this AJAX call. My last resort will be to return some jibberish wrapped in JSONP just to make it work.

Any ideas why IE is screwing up with a CORS request that returns no data?

Answer 1

This is a known bug with jQuery. The jQuery team has "no plans to support this in core and is better suited as a plugin." (See this comment). IE does not use the XMLHttpRequest, but an alternative object named XDomainRequest.

There is a plugin available to support this in jQuery, which can be found here: https://github.com/jaubourg/ajaxHooks/blob/master/src/xdr.js

EDIT The function $.ajaxTransport registers a transporter factory. A transporter is used internally by $.ajax to perform requests. Therefore, I assume you should be able to call $.ajax as usual. Information on transporters and extending $.ajax can be found here.

Also, a perhaps better version of this plugin can be found here.

Two other notes:

1. The object XDomainRequest was introduced from IE8 and will not work in versions below.
2. From IE10 CORS will be supported using a normal XMLHttpRequest.

Edit 2: http to https problem

Requests must be targeted to the same scheme as the hosting page

This restriction means that if your AJAX page is at http://example.com, then your target URL must also begin with HTTP. Similarly, if your AJAX page is at https://example.com, then your target URL must also begin with HTTPS.

Source: http://blogs.msdn.com/b/ieinternals/archive/2010/05/13/xdomainrequest-restrictions-limitations-and-workarounds.aspx