Validate at least one checkbox checked Validation for CheckBox inside Repeater in ASP.Net

i want to check wheather checkbox is selected by user or not. where checkbox is inside gridview

What Data you are downloading.

where is your checkbox is it inside of GridView or Repeater

Thank you.

i hv check box inside repeater so through javascript i just want to check wheather atleast one checkbox is selected by user or not.

Try This

<asp:Repeater id="repeaterentry" runat="server">
    <HeaderTemplate>
        <table border="1" width="100%">
            <colgroup>
                <col style="width: 10px;" />
                <col />
                <col />
            </colgroup>
            <tr>
                <th align="left" class="allCheckbox">
                    <asp:CheckBox ID="allCheckbox1" runat="server" />
                </th>
                <th>
                    <asp:LinkButton ID="lnkbtn1" runat="server" CommandName="UserName">Name</asp:LinkButton>
                </th>
                <th>
                    Password
                </th>
            </tr>
    </HeaderTemplate>
    <ItemTemplate>
        <tr>
            <td class="singleCheckbox">
                <asp:CheckBox ID="chkContainer" runat="server" />
            </td>
            <td>
                <%#Eval("uname") %>
            </td>
            <td>
                <%#Eval("upass")%>
            </td>
        </tr>
    </ItemTemplate>
    <FooterTemplate>
    </table>
    </FooterTemplate>
</asp:Repeater

in js

<script type="text/javascript">
    $(function () {
        var $allCheckbox = $('.allCheckbox :checkbox');
        var $checkboxes = $('.singleCheckbox :checkbox');
        $allCheckbox.change(function () {
            if ($allCheckbox.is(':checked')) {
                $checkboxes.attr('checked', 'checked');
            }
            else {
                $checkboxes.removeAttr('checked');
            }
        });
        $checkboxes.change(function() {
            if ($checkboxes.not(':checked').length) {
                $allCheckbox.removeAttr('checked');
            }
            else {
                $allCheckbox.attr('checked', 'checked');
            }
        });
    });
</script>

working example available

Refer

http://forums.asp.net/t/1906476.aspx

http://dotnetmentors.com/aspnet/jquery-check-uncheck-all-checkboxes-in-gridview.aspx