问题
Is there a difference between the following two xpath expressions?
child::*child::node()
I tried both expressions on this playground page and got the same result.
W3schools says
child::*Selects all element children of the current node
child::node()Selects all children of the current node
but I do not get the difference.
回答1:
Both child::* and child::node() refer to the children of the current node, so the difference is really in the difference between that of an element and a node.
An element is a type of node.
XPath has the following node types in its model of XML:
- element
- attribute
- text
- namespace
- processing instruction (PI)
- comment
- root
For your example XML / HTML,
<html>
<head>
<title>My page</title>
</head>
<body>
<h2>Welcome to my <a href="#">page</a></h2>
<p>This is the first paragraph</p>.
<!-- this is the end -->
</body>
</html>
there are count(//*) = 7 elements and count(//node()) = 21 nodes.
Your playground XPath is //h2/a, which doesn't really illustrate child::* vs child::node().
If instead you consider //h2/* vs //h2/node(), then
//h2/*selects a single node, an element:<a href="#">page</a>//h2/node()selects two nodes, a text node and an element:Welcome to my <a href="#">page</a>
来源：https://stackoverflow.com/questions/52045856/xpath-difference-between-child-and-childnode