客户端验证函数，作用：例如判定复选框必须至少有一个被选中才可以提交

<script language="javascript" type="text/javascript">
       <!--
        function  ClientValidate(sender, args)
        {
       
            var flag = false;
            var  inarr=document.forms[0].all.tags("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>




   <asp:CustomValidator ID="CustomValidator1" runat="server" ClientValidationFunction="ClientValidate"
                        Display="Dynamic" ErrorMessage="请选择印章类型"></asp:CustomValidator>