为什么XPath选择上下文节点之外的节点? [英] Why does XPath select nodes outside of context node?
问题描述
我将XPath与Node.js一起使用，并且拥有以下HTML文档，在该文档中，我想选择所有文章节点，然后在第二步中选择所有具有"abc" 类的div:
I'm using XPath with Node.js and I have the following HTML document, where I want to select all article nodes and then in a second step all divs with class "abc":
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Test</title>
</head>
<body>
<article>
<div>123456</div>
<div class="abc">Hello0!</div>
</article>
<article>
<div>123456</div>
<div class="abc">Hello1!</div>
</article>
<article>
<div>123456</div>
<div class="abc">Hello2!</div>
</article>
<article>
<div>123456</div>
<div class="abc">Hello3!</div>
</article>
<article>
<div>123456</div>
<div class="abc">Hello4!</div>
</article>
<article>
<div>123456</div>
<div class="abc">Hello5!</div>
</article>
<article>
<div>123456</div>
<div class="abc">Hello6!</div>
</article>
<article>
<div>123456</div>
<div class="abc">Hello7!</div>
</article>
<article>
<div>123456</div>
<div class="abc">Hello8!</div>
</article>
<article>
<div>123456</div>
<div class="abc">Hello9!</div>
</article>
</body>
</html>
我使用以下代码选择节点:
I used following code to select the nodes:
var xpath = require('xpath');
var DOMParser = require('xmldom').DOMParser;
let parser: DOMParser = new DOMParser();
let doc = parser.parseFromString("HTML-document","text/xml");
let nodes: Node[] = xpath.select("//article", doc);
console.log("NODES: ", nodes.length);
let divs: Node[] = xpath.select("//div[@class='abc']", nodes[0]);
console.log("DIVS: ", divs.length);
我的问题是，在检查两个控制台日志时，第一个显示"NODES:10" .
My problem is, when checking the two console-logs, the first one says "NODES: 10".
到目前为止，我有十个文章节点.但是，当我在十个文章节点中的第一个节点上再次选择时，控制台会显示"DIVS:10" .因此，XPath从一篇文章中选择了所有10个div，我希望其中只有一个 div .
So far, I have ten article nodes. However, when I select again on the first of the ten article nodes, the console says "DIVS: 10". So XPath selected all 10 divs out of one article, where I expected just one div.
我在做什么错了?
推荐答案
您应注意，//表示在页面上的任何位置从 .//表示从当前节点开始在页面上的任何位置搜索.因此，如果您要从已经找到的 article 元素开始搜索，则需要替换
You should note that // means search wherever on the page starting from root element while .// means search wherever on the page starting from the current node. So if you want to start search from already found article element you need to replace
"//div[@class='abc']"
与
".//div[@class='abc']"
或
"./div[@class='abc']"
as div 是 article
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