CheckBoxList必选验证【转】

<script language="javascript" type="text/javascript">
    function checkIssueType(source,args) {         
        var chkListaTipoModificaciones= document.getElementById ('<%= checkFriendList.ClientID %>');
        var chkLista= chkListaTipoModificaciones.getElementsByTagName("input");
        for(var i=0;i<chkLista.length;i++)
        {   
            if(chkLista[i].checked)
            {
                args.IsValid = true;
                return;
            }
        }
        args.IsValid = false;
    }
</script>

 

<div style="width: 100%; height: 190px; overflow: auto;">
    <asp:CheckBoxList ID="checkFriendList" RepeatColumns="2" runat="server">
    </asp:CheckBoxList>
    <asp:CustomValidator ID="CustomValidator2" runat="server" ErrorMessage="不能为空" ClientValidationFunction="checkIssueType"
        ValidationGroup="CreatGroup">
    </asp:CustomValidator>
</div>