x
 
<html>
<head>
<script type="text/javascript" src="/example/xdom/loadxmldoc.js"> 
</script>
</head>
<body>
<script type="text/javascript">
xmlDoc=loadXMLDoc("/example/xdom/books_ns.xml");
var x=xmlDoc.getElementsByTagName("book")[0];
document.write(x.lookupPrefix("https://www.w3school.org.cn/children/"));
</script>
</body>
</html>