Replace javascript ajax with jquery ajax

I am currently using Javascript + AJAX to request and return the data from a CKeditor instance to a PDF renderer. I need to change this to JQuery + AJAX. I am working in a GSP in Grails 2.4.3.

Here's my working Javascript:

function getCK(){
    return CKEDITOR.instances.thisInstance.getData();
}

function upDate(){

    var xhr = new XMLHttpRequest();

    xhr.open("POST", "https://someURL/app/someController/someAction", false);
    xhr.onreadystatechange = function () {
        if (xhr.status === 200 && xhr.readyState === 4) {

            document.getElementById("pdf").setAttribute("data", xhr.responseText);

        }
    };
    xhr.send(getCK());
}
upDate();

The code above works, but my employer wants JQuery.

Here's what I have so far that doesn't work:

function upDate(){

    $.ajax('${createLink(controller:'someController', action:'someAction')}',{
        type:'POST',
        data: CKEDITOR.instances.thisInstance.getData();
        },
        success: function (data) {
            $('#pdf').attr('data', data);
        },
        error: function(jqXHR, textStatus){ alert(jqXHR.responseText);}
    });
}
upDate();

Not sure why this isn't working, this exact code works throughout our gigantic application numerous times.

Thanks in advance!