<asp:TextBox ID="txtDate" runat="server"></asp:TextBox>
<asp:RequiredFieldValidator ID="reqDate" runat="server" ControlToValidate="txtDate" ErrorMessage="*"></asp:RequiredFieldValidator>
<script type="text/javascript">$("#<%= txtDate.ClientID %>").datepicker();
</script>

$("#<%= txtDate.ClientID %>").datepicker({
onSelect: function(dateText, inst) {
// 不做任何處理
}
});