//判斷起始日期與結束日期大小
        function ckdate() {
            var endtime = $('#txtStorageTimeEnd').val();
            var starttime = $('#txtStorageTimeStart').val();
            var start = new Date(starttime.replace("-", "/").replace("-", "/"));
            var end = new Date(endtime.replace("-", "/").replace("-", "/"));
            if (end < start) {
                alert('結束日期不能小於開始日期！');
                return false;
            }
            else {
                return true;
            }

        }

<asp:TextBox ID="txtStorageTimeStart" runat="server" onclick="setday(this,false)" ></asp:TextBox>
        到

<asp:TextBox ID="txtStorageTimeEnd" runat="server" onclick="setday(this,false)" ></asp:TextBox>

<asp:Button ID="btnSearch" runat="server"  Text="查詢" onclick="btnSearch_Click" OnClientClick="ckdate()" />