在线运行代码 - 菜鸟教程

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程(cainiaoplay.com)</title>
</head>
<body>

<a id="cainiaoplay" hreflang="zh-cn" href="../index.html">菜鸟教程</a><br>
<script>
document.write("返回链接的hreflang: ");
document.write(document.getElementById('cainiaoplay').hreflang);
document.write("<br><br>");
</script>
<a id="google" href="http://www.google.com/">Google</a><br>
<script>
document.getElementById('google').hreflang="no";
document.write("设置链接的hreflang: ");
document.write(document.getElementById('google').hreflang);
</script>

</body>
</html>
源代码

动行结果
