我知道绝对 XPath 会从 XML 树中的根节点返回检查过的节点.
但我无法理解 XPath 中用于检查/查找节点的 .// 的含义.
. 是当前节点；它是 self::node() 的缩写.
// 是descendant-or-self 轴；它是 /descendant-or-self::node()/ 的缩写.
一起，.// 将从当前节点开始沿descendent-or-self 轴进行选择.将此与从文档根开始的 // 对比.
考虑以下 HTML:
<身体><div id="id1"><p>第一段</p><div><p>第二段</p><p>第三段</p>
//p 将选择所有段落:
第一段
<p>第二段</p><p>第三段</p>另一方面，如果当前节点位于 div 元素(具有 "id1" 的 @id)，则 .//p 将只选择当前节点下的段落:
第一段
<p>第二段</p>注意当当前节点为id1 div时.//p没有选中第三段，因为第三段是不在那个 div 元素之下.
I know absolute XPath will return the inspected node from root node in XML tree.
But I am not able to understand the meaning of .// used in XPath to inspect/find a node.
. is the current node; it is short for self::node().
// is the descendant-or-self axis; it is short for /descendant-or-self::node()/.
Together, .// will select along the descendent-or-self axis starting from the current node. Contrast this with // which starts at the document root.
Consider the following HTML:
<html>
<body>
<div id="id1">
<p>First paragraph</p>
<div>
<p>Second paragraph</p>
</div>
</div>
<p>Third paragraph</p>
</body>
</html>
//p will select all paragraphs:
<p>First paragraph</p>
<p>Second paragraph</p>
<p>Third paragraph</p>
On the other hand, if the current node is at the div element (with @id of "id1"), then .//p will select only the paragraphs under the current node:
<p>First paragraph</p>
<p>Second paragraph</p>
Notice that the third paragraph is not selected by .//p when the current node is the id1 div because the third paragraph is not under that div element.
这篇关于XPath 中 .//的含义是什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！