js 取得CheckBoxList的选中项的值

父页面：(TextBox1用来接收子页面（user_code.aspx）传回来的值)

<script language="javascript" type="text/javascript">
function show_win()
{    
    var var_win = 0;
    showModalDialog('user_code.aspx',[window,document.getElementById("TextBox1").id],'status:Modeless;edge:raised;unadorned:no;scroll=no;resizable:yes;center:yes;help:no;dialog520px;dialogheight:420px');
    
}
</script>

子页面（user_code.aspx）：

 <script language="javascript" type="text/javascript">
    function selected_info(str)
    {
       
          var CheckBoxList=document.all.CheckBoxList1;             
          var textbox=document.all.hid_user_code;   
          textbox.value="";   
          var objCheckBox ;
          for(i=0;i<CheckBoxList.rows.length;i++)   
          {   
                objCheckBox   =   document.getElementById("CheckBoxList1_"   +   i); 
                
                if(objCheckBox.checked == true)
                {
                    textbox.value += CheckBoxList.rows[i].cells[0].childNodes(1).innerText + ",";   
                }
          }   
          
           
          window.dialogArguments[0].document.getElementById(window.dialogArguments[1]).value = textbox.value;
          window.close();
    }

    </script>


<form>
 <div>
        &nbsp;
<table style=" 403px; height: 282px">
            <tr>
                <td style=" 100px">
                     <asp:Label ID="Label1" runat="server" Text="用户编号:" Width="72px"></asp:Label>
                </td>
            </tr>
            <tr>
                <td style=" 100px">
                    <asp:CheckBoxList ID="CheckBoxList1" runat="server" >  </asp:CheckBoxList>
                </td>
            </tr>
        </table>
        <hr />
        <asp:Button ID="btn_confirm" runat="server" Text="确定"  />
       </div>
       <input id="hid_user_code" runat="server" type="text" />
    </form>