<html>
<body>
<p>点击按钮获取正文元素的节点类型。</p>
<button onclick="myFunction()">试一试</button>
<p id="demo"></p>
<script>
function myFunction() {
var x = document.body.nodeType;
document.getElementById("demo").innerHTML = x;
}
</script>
</body>
</html>