Update/Delete in GridView using JQuery without page post back

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
    <Columns>
        <asp:BoundField DataField="ProductID" HeaderText="ProductID" />
        <asp:BoundField DataField="ProductName" HeaderText="Product Name" />
        <asp:BoundField DataField="UnitPrice" HeaderText="UnitPrice" />
        <asp:TemplateField HeaderText="Units In Stock">
            <ItemTemplate>
                <asp:TextBox ID="TextBox1" runat="server" Text='<%# Eval("UnitsInStock") %>' 
                   CssClass="stock">
                </asp:TextBox>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField>
            <ItemTemplate>
                <a href="#" id='<%# Eval("ProductID") %>' class="updatebutton">
                <img  border="0" src="Images/update.png" alt="Delete" />
                </a>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

<script src="Scripts/jquery-1.4.1.js" type="text/javascript" > </script >
<script src="Scripts/jquery-1.4.1.min.js" type="text/javascript" > </script>
<script language="javascript" type="text/javascript">
    $(document).ready(function () {
        $(".updatebutton").click(function () {
            var row = $(this).closest("tr");
            //Getting the ID of the record and the data from textbox to update
            var pID = $(this).attr("id");
            var update_data = $(".stock", row).val(); //stock is the CssClass name of the textbox.
            // If you are updating  more than one column, retrieve the value of all the
            //textboxes similarly and then add them in single variable
            //(see below)
            update_data = pID + "," + update_data; //adding both the value in single variable
            //with ',' separator                                
            // Confirming the operation from the user
            if (confirm("Do you want to update this record?")) {
                $.ajax({
                    type: "POST",
                    //UpdateRecordInGridViewUsingJQuery.aspx is the page name and UpdateProduct 
                    // is the server side web method which actually does the updation
                    url: "UpdateRecordInGridViewUsingJQuery.aspx/UpdateProduct",
                    //Passing the record id and data to be updated which is in the variable record_id
                    data: "{'args': '" + update_data + "'}",
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    //Giving message to user on successful updation
                    success: function () {
                        alert("Record successfully updated!!!");
                        //location.reload();
                    }
               });
            }
            return false;
        });
    });
</script>

[System.Web.Services.WebMethod]

public static void UpdateProduct(string args)
{
    string[] data = args.Trim().Split(',');
    try
    {
        SqlConnection conn;
        SqlCommand cmd;

        conn = new SqlConnection();
        conn.ConnectionString = ConfigurationManager.ConnectionStrings["NWConnectionString"].ConnectionString;

        cmd = new SqlCommand();
        cmd.CommandText = "UPDATE Products SET UnitsInStock = @unitsinstock WHERE ProductID = @productid";
        cmd.CommandType = CommandType.Text;
        cmd.Connection = conn;

        cmd.Parameters.AddWithValue("@unitsinstock", data[1]);
        cmd.Parameters.AddWithValue("@productid", Convert.ToInt32(data[0]));

        conn.Open();
        cmd.ExecuteNonQuery();
        conn.Close();
    }
    catch (Exception ex)
    {
        throw ex;
    }
}

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        LoadData(); 
    }
}

protected void LoadData()
{
    SqlConnection conn;
    SqlCommand cmd;
    SqlDataAdapter sda;
    DataTable dt;

    conn = new SqlConnection();
    conn.ConnectionString = ConfigurationManager.ConnectionStrings["NWConnectionString"].ConnectionString;

    cmd = new SqlCommand();
    cmd.CommandText = "SELECT top 5 ProductID, ProductName, UnitPrice, UnitsInStock FROM Products";
    cmd.CommandType = CommandType.Text;
    cmd.Connection = conn;

    dt = new DataTable();
    sda = new SqlDataAdapter();
    sda.SelectCommand = cmd;
    sda.Fill(dt);

    GridView1.DataSource = dt.DefaultView;
    GridView1.DataBind();

    sda.Dispose();
    cmd.Dispose();
    conn.Dispose();            
}