代码示例：（标识：xdom_nav_prevsibling）
<html>
<head>
<script type="text/javascript" src="/static/demo/html/js/loadxmldoc.js">
</script>
<script type="text/javascript">
//check if the first node is an element node
function get_previousSibling(n)
{
y=n.previousSibling;
while (y.nodeType!=1)
{
y=y.previousSibling;
}
return y;
}
</script>
</head>
<body>
<script type="text/javascript">
xmlDoc=loadXMLDoc("/static/demo/xdom/books.xml");
x=get_previousSibling(xmlDoc.getElementsByTagName("price")[0]);
document.write(x.nodeName);
</script>
</body>
</html>
