var adServingCookieURL = "//wlkwiff.adsrv.eacdn.com/AdServingData/CookieData.ashx?Priority=last&Check=Clicks";

CrossDomainServiceCaller(adServingCookieURL, {}, true, SetAdServingReferralCookie);

function SetAdServingReferralCookie(data) {
    jQuery("#AdServingReferralBTAG").appendTo("#registrationform");
    jQuery("#AdServingReferralBTAG").val(data.btag);
}

function CrossDomainServiceCaller(URL, PostData, Async, AsyncCallback) {
    var xmlHttp = null;

    if (window.XMLHttpRequest) {
        // FireFox, Safari, etc.
        xmlHttp = new XMLHttpRequest();

        try {
            xmlHttp.overrideMimeType('text/plain'); // Or anything else
        } catch (err) { }
    }
    else if (window.ActiveXObject) {
        // MSIE
        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
    }
    else {
        xmlHttp = new XMLHttpRequest();
    }

    //do not let it be async if redirect is triggered.
    if (Async == null) {
        Async = false;
    }

    xmlHttp.withCredentials = true;

    if (Async) {
        xmlHttp.onreadystatechange = function () {
            if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {
                AsyncCallback(jQuery.parseJSON(xmlHttp.responseText));
            }
        }
    }

    xmlHttp.open('POST', URL, Async);

    if (PostData != null) {
        var formString = "";

        for (var key in PostData) {
            if (PostData.hasOwnProperty(key)) {
                formString += key + "=" + encodeURIComp(PostData[key]) + "&";
            }
        }

        xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
        xmlHttp.send(formString);
    }
    else {
        xmlHttp.send();
    }

    if (!Async && xmlHttp.status == 200) {
        return xmlHttp.responseText;
    }
}