Web-scraping - 如何在 Puppeteer JS 可用时导航 link

Question

我想对 url https://data.anbima.com.br/debentures/AGRU12/agenda 中主要 table 正文中的所有数据执行网络抓取 ...然而，由于它实现了分页，我无法轻松完成......我想出了以下不起作用的代码......我收到错误 ReferenceError: list is not defined，尽管我已经在while 循环...

const puppeteer = require('puppeteer');
const fs = require('fs');
(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto(`https://data.anbima.com.br/debentures/AGRU12/agenda`);
  await page.waitForSelector('.normal-text');
  var list = [];
  while (true) {
    let nextButton;
    await page.evaluate(async () => {
      const nodeList = document.querySelectorAll(
        '.anbima-ui-table > tbody > tr'
      );
      let nodeArray = [...nodeList];
      nextButton = document.querySelector('.anbima-ui-pagination__next-button');

      let listA = nodeArray
        .map((tbody) => [...tbody.children].map((td) => [...td.children]))
        .map((tr) =>
          tr.map((span) =>
            span[0].innerHTML
              .replace('<label class="flag__children">', '')
              .replace('</label>', '')
          )
        );
      list.push(listA);
    });

    if (!nextButton) {
      break;
    } else {
      await page.goto(nextButton.href);
    }
  }

  fs.writeFile('eventDates.json', JSON.stringify(list[0], null, 2), (err) => {
    if (err) throw new Error('Something went wrong');

    console.log('well done you got the dates');
  });
  await browser.close();
})();

Answer 1

List 在回调函数中未定义。您需要 return page.evaluate 中的数组，然后使用该 returned 数组将其推送到列表。

const list = [];
while (true) {
    let nextButton;
    const listA = await page.evaluate(async () => {
        const nodeList = document.querySelectorAll(
            '.anbima-ui-table > tbody > tr'
        );
        let nodeArray = [...nodeList];
        nextButton = document.querySelector('.anbima-ui-pagination__next-button');

        return nodeArray
            .map((tbody) => [...tbody.children].map((td) => [...td.children]))
            .map((tr) =>
                tr.map((span) =>
                    span[0].innerHTML
                        .replace('<label class="flag__children">', '')
                        .replace('</label>', '')
                )
            );
    });
    list.push(...listA);

编辑：更正了示例中的最后一行。

Web-scraping - 如何在 Puppeteer JS 可用时导航 link

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recurrence

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while-loop

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