<html>
<body>
<h1>Document 对象</h1>
<h2>scripts 属性</h2>
<script>
document.write("Hello World!");
</script>
<p>文档中脚本元素的数量:</p>
<p id="demo"></p>
<script>
document.getElementById("demo").innerHTML = document.scripts.length;
</script>
</body>
</html>