通过 x-ray/node 抓取黑客新闻

Question

如何通过 x-ray/nodejs 抓取黑客新闻 (https://news.ycombinator.com/)？

我想从中得到这样的东西：

[
  {title1, comment1},
  {title2, comment2},
  ...
  {"‘Minimal’ cell raises stakes in race to harness synthetic life", 48}
  ...
  {title 30, comment 30}
]

有个新闻table但是我不知道怎么抓取它... 网站上的每个故事都由三栏组成。它们没有它们独有的 parent。所以结构看起来像这样

<tbody>
  <tr class="spacer"> //Markup 1
  <tr class="athing"> //Headline 1 ('.deadmark+ a' contains title)
  <tr class>          //Meta Information 1 (.age+ a contains comments)
  <tr class="spacer"> //Markup 2
  <tr class="athing"> //Headline 2 ('.deadmark+ a' contains title)
  <tr class>          //Meta Information 2 (.age+ a contains comments)
  ...
  <tr class="spacer"> //Markup 30
  <tr class="athing"> //Headline 30 ('.deadmark+ a' contains title)
  <tr class>          //Meta Information 30 (.age+ a contains comments)

到目前为止我已经尝试过：

x("https://news.ycombinator.com/", "tr", [{
  title: [".deadmark+ a"],
  comments: ".age+ a"
}])

和

x("https://news.ycombinator.com/", {
  title: [".deadmark+ a"],
  comments: [".age+ a"]
})

第二种方法 returns 30 个名称和 29 个 comment-couts... 我看不出有任何可能将它们映射到一起，因为没有信息表明 30 个标题中的哪个缺少评论。 ..

任何帮助都适用

Answer 1

标记不容易用 X-ray 包抓取，因为有 no way to reference the current context in a CSS selector。这对于获取 tr.thing 行之后的下一个 tr 兄弟以获取评论很有用。

我们仍然可以使用 "next sibling" notation（+）进入下一行，但是，我们不再针对可选注释 link，而是获取完整的行文本，然后使用正则表达式提取评论值。如果没有评论，则将值设置为 0.

完整的工作代码：

var Xray = require('x-ray');
var x = Xray();

x("https://news.ycombinator.com/", {
    title: ["tr.athing .deadmark+ a"],
    comments: ["tr.athing + tr"]
})(function (err, obj) {
    // extracting comments and mapping into an array of objects
    var result = obj.comments.map(function (elm, index) {
        var match = elm.match(/(\d+) comments?/);
        return {
            title: obj.title[index],
            comments: match ? match[1]: "0"
        };
    });
    console.log(result);
});

当前打印：

[ { title: 'Follow the money: what Apple vs. the FBI is really about',
    comments: '85' },
  { title: 'Unable to open links in Safari, Mail or Messages on iOS 9.3',
    comments: '12' },
  { title: 'Gogs – Go Git Service', comments: '13' },
  { title: 'Ubuntu Tablet now available for pre-order',
    comments: '56' },
  ...
  { title: 'American Tech Giants Face Fight in Europe Over Encrypted Data',
    comments: '7' },
  { title: 'Moving Beyond the OOP Obsession', comments: '34' } ]

通过 x-ray/node 抓取黑客新闻

scrape hacker news via x-ray/node

node.js

web-scraping

x-ray