请教用JS检测UpdatePanel 中的DataList 中的 CheckBoxList 是否有被选中，无选中则弹出提示框？

Question

请教！用JS检测UpdatePanel  中的DataList 中的 CheckBoxList 是否有被选中，无选中则弹出提示框
页面代码如下：<div style="height: 100%">
                        <asp:HiddenField ID="hfUserid" runat="server" />
                        <asp:HiddenField ID="hfMesid" runat="server" />
                        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                            <ContentTemplate>
                                <asp:DataList ID="dlt" runat="server" DataKeyField="autoid" OnItemDataBound="dlt_ItemDataBound"
                                    RepeatDirection="Vertical">
                                    <ItemTemplate>
                                        <asp:CheckBox ID="cb" runat="server" OnCheckedChanged="cb_CheckedChanged" AutoPostBack="true" /><%#Eval("MenuName") %>
                                        <asp:CheckBoxList ID="cbl" AutoPostBack="true" runat="server" RepeatDirection="Horizontal"
                                            RepeatColumns="6">
                                        </asp:CheckBoxList>
                                    </ItemTemplate>
                                </asp:DataList>
                            </ContentTemplate>
                        </asp:UpdatePanel>
                    </div>

Answer 1

你得看这些控件在客户端生成的html，然后就简单了。

Answer 2

var els = document.getElementById('<%=dlt.ClientID%>').getElementByTagName('input');
var flag=true;for(var i=0,len=els.length;i<len;i++)
{
     if(els[i].type=='checkbox'&&els[i].checked)
     {
           flag=false;
           break;
      }
}if(flag)
{
    alert('必须选中一项');
}

Answer 3

getElementByTagName('input');=>getElementsByTagName('input');

Answer 4

但是执行不到if(els[i].type=='checkbox'&&els[i].checked)
这里，总是提示选择一项，但已经选了

Answer 5

对了，我现在是判断一棵树，页面代码如下：
<form id="form1" runat="server">
    <div style="width: 500px; text-align: center; margin-left: 20%">
        <table style="width: 100%; border: 0; background-color: #b5d6e6" cellpadding="0"
            cellspacing="1">
            <tr>
                <td colspan="2" style="height: 22px; background-image: url(../images/bg.gif)">
                    &nbsp;&nbsp;&nbsp;&nbsp;角色信息
                </td>
            </tr>
            <tr>
                <td style="width: 7%; height: 25px; text-align: center; background-color: #FFFFFF">
                    角色名
                </td>
                <td style="text-align: center; background-color: #FFFFFF; width: 36%">
                    <asp:TextBox ID="txtRoleName" runat="server" onblur="this.style.background='#FFFFFF'"
                        onfocus="this.style.background='#e4f8f0';" Width="95%" />
                    <asp:HiddenField ID="hfNewid" runat="server" />
                    <asp:HiddenField ID="hfTypeID" runat="server" />
                    <asp:HiddenField ID="hfRoleID" runat="server" />
                </td>
            </tr>
            <tr>
                <td style="height: 25px; text-align: center; background-color: #FFFFFF">
                    权限
                </td>
                <td style="text-align: left; background-color: #FFFFFF;">
                    <asp:TreeView ID="TreeMenu" runat="server" ShowLines="True" ShowCheckBoxes="All">
                    </asp:TreeView>
                </td>
            </tr>
            <tr>
                <td style="height: 25px; text-align: center; background-color: #FFFFFF">
                    备注
                </td>
                <td style="text-align: center; background-color: #FFFFFF">
                    <asp:TextBox ID="txtRe" runat="server" onblur="this.style.background='#FFFFFF'"
                        onfocus="this.style.background='#e4f8f0';" Width="95%"></asp:TextBox>
                </td>
            </tr>
            <tr>
                <td style="text-align: center; background-color: #FFFFFF; height: 25" colspan="2">
                    <asp:Button ID="btnSubmit" runat="server" CssClass="button60F" Text="确认" OnClientClick="return DataCheck()"
                        OnClick="btnSubmit_Click" />
                    <asp:Button ID="btnBack" runat="server" CssClass="button60" Text="返回" OnClick="btnBack_Click" />
                </td>
            </tr>
        </table>
    </div>
    </form>

Answer 6

你用div 将树包裹eg:<div id='div'>
<asp:TreeView ID="TreeMenu" runat="server" ShowLines="True" ShowCheckBoxes="All">
  </asp:TreeView>
</div>然后var els = document.getElementById('<%=dlt.ClientID%>').getElementByTagName('input');=》var els = document.getElementById('div').getElementByTagName('input');

Answer 7

再这里弹的错var els = document.getElementById('div').getElementByTagName('input');

Answer 8

var els = document.getElementById('div').getElementsByTagName('input');