<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>W3Cschool教程(w3cschool.cn)</title>
</head>
<body>
<p id="demo">单击“按钮”获取文档第一个子节点的节点名称。</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction(){
var x=document.getElementById("demo");
x.innerHTML=document.firstChild.nodeName;
}
</script>
</body>
</html>