js 获取checkbox的值出现undefined

html代码如下：
<td><div id="xuanxiang">  
                                        <%
                                            String str = list.get(0).getquestioncontent();
                                            String[] contents = str.split("\\|");
                                            for (int i = 0; i < contents.length; i++) {
                                        %>
                                        <br/>
                                        <input type="checkbox" />
                                        <input type="text" value="<%=contents[i]%>"/>
                                        <input type="button" value="删除"/>
                                        <%
                                            }
                                        %>
                                    </div></td>

JS代码如下：
function xuanxiang()
{
    var inputdiv = document.getElementById("xuanxiang");  
  &nbs