Get Logged In User Manager in Look Field

function GetCurrentUserRole()
{
    var userid = Xrm.Page.context.getUserId();

   //Get user Manager    
   GetManager(userid);
}

// get manager id

function GetManager(userid) {
//alert(userid);
    var serverUrl = Xrm.Page.context.getClientUrl();
    var oDataSelect = serverUrl + "/XRMServices/2011/OrganizationData.svc/SystemUserSet?$select=ParentSystemUserId &$filter=SystemUserId eq guid'" + userid + "'";

    var retrieveReq = new XMLHttpRequest();
    retrieveReq.open("GET", oDataSelect, false);
    retrieveReq.setRequestHeader("Accept", "application/json");
    retrieveReq.setRequestHeader("Content-Type", "application/json;charset=utf-8");
    retrieveReq.onreadystatechange = function () {
    GetManagerId(this);
};
    retrieveReq.send();
}

function GetManagerId(retrieveReq) {
    if (retrieveReq.readyState == 4) {
        if (retrieveReq.status == 200) {
            var retrieved = JSON.parse(retrieveReq.responseText).d;
            var managerGuid = retrieved.results[0].ParentSystemUserId.Id;
            var managername = retrieved.results[0].ParentSystemUserId.Name;
            var entityType = 'systemuser';
           if(managerGuid!=null)
           {
                Xrm.Page.getAttribute("new_manager").setValue([{ id: managerGuid, name:  managername , entityType: entityType}]);
                Xrm.Page.getControl("new_manager").setDisabled(true);
          }
    else
        {
              Xrm.Page.getControl("new_manager").setDisabled(false);
         }
      }
    }
}