minus 2 template field with javascript

[niloofar]

hi
i have 3 templatefield

 <telerik:GridTemplateColumn HeaderText="????">
                    <ItemTemplate>
                    <asp:Label ID="lblPrice" runat="server" Text='<%# CDS.Savin.WebUI.Generals.General.numberToMoney(Eval("Price").ToString()) %>' ></asp:Label>
                    </ItemTemplate>
                    </telerik:GridTemplateColumn>
                     <telerik:GridTemplateColumn HeaderText="?????">
                    <ItemTemplate>
                    <asp:TextBox runat="server" ID="txtDiscount" OnKeyUp="keyupHandler1();" ></asp:TextBox>
                    </ItemTemplate>
                    </telerik:GridTemplateColumn>
                       <telerik:GridTemplateColumn HeaderText="???? ??" >
                    <ItemTemplate>
                    <asp:Label runat="server" ID="lblTotalPrice"></asp:Label>
                    </ItemTemplate>
                    </telerik:GridTemplateColumn>
when user type number in to "txtDiscount " i want :lblTotalPrice.Text=lblPrice.text-txtDiscount.Text
please help to me
thanks

[Shinu]

 Hello Niloofar,

You can attach the 'onkeyup' event to the TextBox from code behind and pass the ID of txtDiscount, lblPrice, lblTotalPrice to the client event handler. Then you can do the required calculations from client side as shown below. 

C#:

protected void RadGrid1_ItemCreated(object sender, GridItemEventArgs e)
  {
      if (e.Item is GridDataItem)
      {
          GridDataItem item = (GridDataItem)e.Item;
          TextBox txtDiscount = (TextBox)item.FindControl("txtDiscount");
          Label lblPrice = (Label)item.FindControl("lblPrice");
          Label lblTotalPrice = (Label)item.FindControl("lblTotalPrice");
          txtDiscount.Attributes.Add("onkeyup", "return keyupHandler1('" + txtDiscount.ClientID + "','" + lblPrice.ClientID + "','" + lblTotalPrice.ClientID + "')");
      }
  }

JavaScript:

function keyupHandler1(txtBoxId1, lblID, txtBoxId2)
  {
      var txtDiscount = document.getElementById(txtBoxId1);
      var lblPrice = document.getElementById(lblID);
      var lblTotalPrice = document.getElementById(txtBoxId2);
      lblTotalPrice.innerHTML = parseInt(lblPrice.innerHTML) - parseInt(txtDiscount.value);

  }

Thanks,
Shinu.