Javascript in update panel doesn't work after partial postback

Question

 <script type="text/javascript">
        $(function () {
            $('.datePicker').datetimepicker({ dateFormat: 'dd/mm/yy' });
        });
    </script>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="Server">
    <asp:ScriptManager ID="ScriptManager1" runat="server">
    </asp:ScriptManager>
    <asp:TextBox ID="TextBox1" class="datePicker" runat="server"></asp:TextBox>
    <asp:UpdatePanel ID="holder" runat="server" UpdateMode="Always" ChildrenAsTriggers="true">
        <ContentTemplate>
            <asp:DropDownList runat="server" ID="ddl_RespondBy" AutoPostBack="true" OnSelectedIndexChanged="ddl_SelectedIndexChanged">
                <asp:ListItem Selected="True">1 Hour</asp:ListItem>
                <asp:ListItem>Other</asp:ListItem>
            </asp:DropDownList>
            <asp:TextBox ID="txt_RespondBy" class="datePicker" Visible="true" runat="server" />
        </ContentTemplate>
        <Triggers>
            <asp:AsyncPostBackTrigger ControlID="ddl_RespondBy" EventName="SelectedIndexChanged" />
        </Triggers>
    </asp:UpdatePanel>
</asp:Content>

protected void ddl_SelectedIndexChanged(object sender, EventArgs e)
    {
        if (ddl_RespondBy.SelectedItem.Text == "Other")
        {
            txt_RespondBy.Visible = true;
        }
        else
        {

        }
    }

I do partial post back with the update panel, I have two text box one outside update panel and one inside, when I select other from the dropdown and try to open the calendar inside the txt_RespondBy text box it doesn't show, but the text box outside update panel shows the calendar. why is Javascript not working inside update panel after partial postback

Answer 1

Place your datetimepicker initialisation code in the pageLoad function, which is called whenever the page loads (asynchronously or synchronously).

<script type="text/javascript">
    function pageLoad(sender, args) {
        $('.datePicker').datetimepicker({ dateFormat: 'dd/mm/yy' });
    }      
</script>