xdomainrequest.js

// override default jQuery transport for IE
if(window['XDomainRequest']) {
    // save default xhr
    jQuery.ajaxSettings.xhr_back = jQuery.ajaxSettings.xhr;
    jQuery.ajaxSettings.xhr = function() {
        if(this.crossDomain) {
            try {
                // IE sucs
                var xhr = new window.XDomainRequest();
                xhr.onload = function() {
                    setTimeout(function(a,b,c) {
                        xhr.readyState = 4;
                        xhr.status = 200;
                        xhr.getAllResponseHeaders = function(){return '';}
                        xhr.onreadystatechange.apply(this, arguments);
                    }, 22);
                };
                return xhr;
            } catch(e) {}
        }
        // return original xhr
        return jQuery.ajaxSettings.xhr_back.apply(this, arguments);
    };

    // also, override the support check
    jQuery.support.cors = true;
}