The code is as follows:
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<div id="content"></div>
<script>
var el = document.createElement("div");
el.innerHTML = ' <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>titleValue</title> <meta name="description" content="It is a good way to learn science." /> <meta name="keywords" content="Symfony2,Redis,PHP" /> <meta name="author" content="CSDN.NET" /> <meta name="Copyright" content="CSDN.NET" /> </head> <body> hello</body> </html>';
var descElements = el.getElementsByTagName("head");
document.getElementById("content").innerHTML = descElements.length;
</script>
</body>
</html>1. If the script is placed in the head element, when the script is loaded, the div element has not been loaded, and "document.getElementById(...) is empty or not an object" will appear.
2. The above code works normally in chrome, and the output result is 5, but in IE, the output result is 0.
3. Note that you do not need to use [] when defining data in js, otherwise an error will occur.
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
