After applying this code, I encountered an issue where the textbox does not accept input with a decimal point .
.
<asp:TextBox ID="txtDetAmount" runat="server" AutoPostBack="true"
OnTextChanged="OntxtDetAmountChanged"
style="width: 50%;" AutoComplete="off"
onkeydown = "return (!(event.keyCode>=65) && event.keyCode!=32);">
</asp:TextBox>