public class JsonpResult : System.Web.Mvc.JsonResult
    {
        object data = null;

        public JsonpResult()
        {
        }

        public JsonpResult(object data)
        {
            this.data = data;
        }

        public override void ExecuteResult(ControllerContext controllerContext)
        {
            if (controllerContext != null)
            {
                HttpResponseBase Response = controllerContext.HttpContext.Response;
                HttpRequestBase Request = controllerContext.HttpContext.Request;

                string callbackfunction = Request["callback"];
                if (string.IsNullOrEmpty(callbackfunction))
                {
                    throw new Exception("Callback function name must be provided in the request!");
                }
                Response.ContentType = "application/x-javascript";
                if (data != null)
                {
                    JavaScriptSerializer serializer = new JavaScriptSerializer();
                    Response.Write(string.Format("{0}({1});",callbackfunction,serializer.Serialize(data)));
                }
            }
        }

    }