js实现,获取同级别的某个结点

Question

<div>
                    <input type="hidden" id="personId" name="personId[]" value="0" />
                    <span>乘机人姓名:</span>
                    <input type="text" id="passgenerName" name="passgenerName[]" /><font color="red">(必填)</font>
                    <span>证件类型:</span>
                    <select id="certifyType" name="certifyType[]">
                        <option value="0" selected>身份证</option>
                        <option value="1">士兵证</option>
                        <option value="2">军官证</option>
                    </select><font color="red">(必填)</font>
                    <span>证件号码:</span>
                    <input type="text" id="certifyNo" name="certifyNo[]" onblur="javascript:return authDocument(this);" /><font color="red">(必填)</font>
                    <span>类型:</span>
                    <select id="personType" name="personType[]">
                        <option value="1" selected>成人</option>
                        <option value="2">儿童</option>
                    </select><font color="red">(必填)</font>
                    <span>购买保险:</span>
                    <select id="Insure" name="Insure[]">
                        <option value="0">0</option>
                        <option value="1" selected>1</option>
                    </select>(20元)/份<font color="red">(必填)</font><br/>
                    <span>生日:</span>
                    <input type="text" id="birthday" name="birthday[]" /><br/>
                </div>当证件号码的文本框失去焦点时,怎样获取到同级的证件类型的值?请高人帮忙看看！

Answer 1

可以用previousSibling找上面的同级元素 。
但是主要要排除文本节点 。

Answer 2

function authDocument(obj){
  var id = obj.id, tid = "certifyType"+id.substring("certifyNo".length);
  var ctype = document.getElementById(tid);
  
  alert(ctype.value);
  return ctype.value;
}用ID做手脚吧,同级别的证件号码ID和证件类型ID后面的数字做成一样的就可以了.