var mylist = document.getElementById("tcon");
var lis = mylist.parentNode.parentNode.parentNode;
document.write(lis.lastChild.innerHTML);
var mylist = document.getElementById("tcon");
document.write(mylist.parentNode.parentNode.parentNode.lastChild.innerHTML);
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
</head>
<body>
<ul id="con">
<li id="lesson1">javascript
<ul>
<li id="tcon"> 基础语法</li>
<li>流程控制语句</li>
<li>函数</li>
<li>事件</li>
<li>DOM</li>
</ul>
</li>
<li id="lesson2">das</li>
<li id="lesson3">dadf</li>
<li id="lesson4">HTML/CSS
<ul>
<li>文字</li>
<li>段落</li>
<li>表单</li>
<li>表格</li>
</ul>
</li></ul>
<script type="text/javascript">
var mylist = document.getElementById("tcon");
var lis = mylist.parentNode.parentNode.parentNode;
document.write(lis.lastChild.innerHTML);
</script>
</body>
</html>
<!DOCTYPE HTML><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>无标题文档</title></head><body><ul id="con"><li id="lesson1">javascript <ul> <li id="tcon"> 基础语法</li> <li>流程控制语句</li> <li>函数</li> <li>事件</li> <li>DOM</li> </ul></li><li id="lesson2">das</li><li id="lesson3">dadf</li><li id="lesson4">HTML/CSS <ul> <li>文字</li> <li>段落</li> <li>表单</li> <li>表格</li> </ul> </li></ul> <script type="text/javascript"> var mylist = document.getElementById("tcon"); var lis = mylist.parentNode.parentNode.parentNode; document.write(lis.lastChild.innerHTML);</script> </body></html>
我试了是undefinded
输出来了吗