使用 puppeteer 遍历表

Question

我想从表格中的网站获取数据。首先，我尝试获取整个表，然后获取其中的tr 和td。我现在的代码只是返回空数组。

const puppeteer = require("puppeteer");

async function run() {
  const browser = await puppeteer.launch({ headless: false });
  const page = await browser.newPage();
  await page.goto(
    "https://www.basketball-reference.com/leagues/NBA_2021_standings.html" //Eastern Conference
  );

  var temp = [];
  const data = await page.evaluate(() => {
    const tableBody = document.querySelector(
      'table[id="confs_standings_E"] tbody'
    );

     for (var i = 0; i < tableBody.length; i++) {
      const tr = tableBody[i].querySelectorAll("tr");
      for (var j = 0; j < tr.length; j++) {
       const td = tr[j].querySelectorAll("td").innerText;
       temp.push(td);
  }
}
  });

  console.log(temp);
  //await browser.close();
}

run();

更新

我尝试了发布的解决方案，它确实有效，非常感谢，但我想尝试以另一种方式获得解决方案。下面的代码得到了正确数量的元素，但它们都是undefined 这是我在控制台中得到的：

0: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
1: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
2: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
3: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
4: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
5: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
6: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
7: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
8: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
9: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
10: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
11: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
12: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
13: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]
14: (7) [undefined, undefined, undefined, undefined, undefined, undefined, undefined]

这是新代码：

async function run() {
  const browser = await puppeteer.launch({ headless: false });
  const page = await browser.newPage();
  await page.goto(
    "https://www.basketball-reference.com/leagues/NBA_2021_standings.html" //Eastern Conference
  );

  seznamEkip = [];
  const ekipe = await page.$$("#confs_standings_E tbody tr");

  for (const ekipa of ekipe) {
    const podatki = await ekipa.$$("td");
    const spread = [...podatki].map((element) => element.innerText);
    seznamEkip.push(spread);
  }

  console.log(seznamEkip);
}

run();

感谢您的帮助

Answer 1

回想一下 document.querySelector 返回单个元素，而不是数组。因此，用 for 循环遍历它的长度是没有意义的，因为它没有长度——它只是一个元素。您可能会发现迭代 element's .children instead 很有用。

作为替代方案，请考虑使用 querySelectorAll 并改用稍微不同的选择器。例如，这将选择 tbody 中的每个 td，并返回其innerTexts 的数组：

const data = await page.evaluate(() => {
    const tableBody = document.querySelectorAll('#confs_standings_E tbody td');
    return Array.from(tableBody).map(element => element.innerText);
});
console.log(data);