ASP.NET使用CustomValidator空间和JavaScript验证至少选一项

<script language="javascript" type="text/javascript"> 
        <!--
        function  ClientValidate(sender, args)
        {
            var flag = false;
            var radioList=document.getElementById("CheckBoxList1"); 
            var inarr = radioList.getElementsByTagName('input'); 
            for (var i=0; i<inarr.length; i++)
            {
                if(inarr[i].type=="checkbox")
                 {
                    if(inarr[i].checked==true)    
                     {
                         flag = true;
                     }
                  }
             }
             if (flag)
             {
                args.IsValid = true;
             }
             else
             {
                args.IsValid = false;
             }
        }
        -->
</script>

放在checkboxlist后面
<asp:CustomValidator ID="CustomValidator1" runat="server" ClientValidationFunction="ClientValidate"
            Display="Dynamic" ErrorMessage="请选择机构类型"></asp:CustomValidator>