​x
 
<!DOCTYPE html>
<html>
<body><p id="demo">点击按钮来获得 body 元素首个子节点的名称。</p>
​
<button onclick="myFunction()">试一下</button>
​
<script>
function myFunction()
{
var x=document.getElementById("demo");  
x.innerHTML=document.body.childNodes.item(0).nodeName;
}
</script>
​
</body>
</html>
​