Validating ASP.Net CheckBoxList using Custom Validator control.

<asp:CheckBoxList ID = "chk_emloyee" runat = "server">
    <asp:ListItem Text = "Vishal" />
    <asp:ListItem Text = "Manoj" />
    <asp:ListItem Text = "Kumar" />
    <asp:ListItem Text = "Neeraj" />
    <asp:ListItem Text = "Gautam" />
    <asp:ListItem Text = "Rajesh" />
    <asp:ListItem Text = "Pappi" />
</asp:CheckBoxList>

<asp:CustomValidator ID = "cstm_val_emp" ErrorMessage = "Please select at least one item."
    ForeColor = "Red" ClientValidationFunction = "Validate_Emp_Chkboxlist" runat = "server" />
<br />

<asp:Button ID = "btn_submit" Text = "Submit" runat = "server" /><br />

<script type="text/javascript">
        function Validate_Emp_Chkboxlist(sender, args)
        {
            var checkBoxList = document.getElementById("<%=chk_emloyee.ClientID %>");
            var checkboxes = checkBoxList.getElementsByTagName("input");
            var isValid = false;

            for (var i = 0; i < checkboxes.length; i++)
            {
                if (checkboxes[i].checked)
                {
                isValid = true;
                break;
            }
        }
        args.IsValid = isValid;
    }
</script>