jQuery CORS Plugin - transparently add CORS support for IE8+ in jQuery using XDomainRequest. Support cookies.

jquery.xdomain.js

(function($) {
    var urlParseRE = /^(((([^:\/#\?]+:)?(?:\/\/((?:(([^:@\/#\?]+)(?:\:([^:@\/#\?]+))?)@)?(([^:\/#\?]+)(?:\:([0-9]+))?))?)?)?((\/?(?:[^\/\?#]+\/+)*)([^\?#]*)))?(\?[^#]+)?)(#.*)?/;

    function parseUrl(url) {
        if (typeof url === "object") {
            return url;
        }
        var u = url || "", matches = urlParseRE.exec(url), results;
        if (matches) {
            results = {
                href: matches[0] || "",
                hrefNoHash: matches[1] || "",
                hrefNoSearch: matches[2] || "",
                domain: matches[3] || "",
                protocol: matches[4] || "",
                authority: matches[5] || "",
                username: matches[7] || "",
                password: matches[8] || "",
                host: matches[9] || "",
                hostname: matches[10] || "",
                port: matches[11] || "",
                pathname: matches[12] || "",
                directory: matches[13] || "",
                filename: matches[14] || "",
                search: matches[15] || "",
                hash: matches[16] || ""
            };
        }
        return results || {};
    }

    function createXDR() {
        try {
            var xdr = new window.XDomainRequest();
            if (!xdr.setRequestHeader) {
                xdr.setRequestHeader = $.noop;
            }
            if (!xdr.getAllResponseHeaders) {
                xdr.getAllResponseHeaders = $.noop;
            }
			xdr.onload = function() {
				setTimeout(function(){
                if (typeof xdr.onreadystatechange === 'function') {
						xdr.readyState = 4;
						xdr.status = 200;
						xdr.onreadystatechange.call(xdr, null, false);
					}
				}, 0);
			};
            xdr.onerror = xdr.ontimeout = function() {
				setTimeout(function(){
                if (typeof xdr.onreadystatechange === 'function') {
						xdr.readyState = 4;
						xdr.status = 500;
						xdr.onreadystatechange.call(xdr, null, false);
					}
				}, 0);
			};
            return xdr;
        } catch(e) {
        }
    }

    if(!$.ajaxSettings.oldXhr) {
        $.ajaxSettings.oldXhr = $.ajaxSettings.xhr;
    }
    
    if ($.browser.msie && window.XDomainRequest) {
        $.support.cors = true;
        $.ajaxSettings.xhr = function() {
            var domain = parseUrl(this.url).domain;
            return domain === "" || domain === parseUrl(document.location.href).domain ?
                $.ajaxSettings.oldXhr() :
                createXDR();
        };
    }

})(jQuery);