Unhandled exception at line 133, column 5 in http://localhost:49647/Account/Login

0x800a1391 - JavaScript runtime error: '$' is undefined

using System;
using System.Data.SqlClient;
using System.Data;
using System.Configuration;

namespace Login.BL
{
    public class User
    {
        public int UserID { get; set; }
        //[Required]
        public int Username { get; set; }
        //[Required]
        public int UserPassword { get; set; }

    }
    public class UserBusinessLogic
    {
        string conStr = ConfigurationManager.ConnectionStrings["myTaylorWoodrowSQL"].ConnectionString;
        public int CheckUserLogin(User User)
        {
            //Check the user is valid!!!!
            using (SqlConnection conObj = new SqlConnection(conStr))
            {
                SqlCommand comObj = new SqlCommand("retrieveUserByNameAndPassword", conObj);
                comObj.CommandType = CommandType.StoredProcedure;
                comObj.Parameters.Add(new SqlParameter("@Username", User.Username));
                comObj.Parameters.Add(new SqlParameter("@Password", User.UserPassword));
                conObj.Open();
                return Convert.ToInt32(comObj.ExecuteScalar());
            }
        }
    }
}

<script>
    $("#Login").click(function ()
    {
        var dataObject = { UserName: $("#UserName").val(), Password: $("#Password").val() };
        $.ajax({
            url:'@Url.Action("Login","User")',
            type:"POST",
            data: dataObject,
            datatype: "json",
            success: function(result)
            {
                if(result.toString()=="Success")
                {
                    alert(result);
                }
                else
                {
                    alert(result);
                }
            },
            error: function (result)
            {
                alert("Error");
            }
        });
    })
</script>