Allow only Numeric values in ASP Text box control using JavaScript

Write the following code in .aspx head tag

<script language="Javascript">
       <!--
       function isNumberKey(evt)
       {
          var charCode = (evt.which) ? evt.which : event.keyCode
          if (charCode != 46 && charCode > 31
            && (charCode < 48 || charCode > 57))
             return false;

          return true;
       }
       //-->
</script>

Call this event on required textboxes

<asp:TextBox ID="Txt_Others" runat="server" onkeypress="return isNumberKey(event)"
                    CssClass="TextBox" required="" Text="0"></asp:TextBox>