Puppeteer $.eval 选择嵌套元素

Question

假设我给出的情况类似于此页面

<div id="details-container" class="style-scope ytd-channel-about-metadata-renderer">
         <yt-formatted-string class="subheadline style-scope ytd-channel-about-metadata-renderer">Details</yt-formatted-string>
        <table class="style-scope ytd-channel-about-metadata-renderer">
          <tbody class="style-scope ytd-channel-about-metadata-renderer"><tr class="style-scope ytd-channel-about-metadata-renderer">
            <td class="label style-scope ytd-channel-about-metadata-renderer">
              <yt-formatted-string class="style-scope ytd-channel-about-metadata-renderer"></yt-formatted-string>
            </td>
            <td class="style-scope ytd-channel-about-metadata-renderer">
              <ytd-button-renderer align-by-text="" class="style-scope ytd-channel-about-metadata-renderer" button-renderer=""></ytd-button-renderer>
              <div id="captcha-container" class="style-scope ytd-channel-about-metadata-renderer"></div>
              <div id="email-container" class="style-scope ytd-channel-about-metadata-renderer"></div>
              <a id="email" target="_blank" class="style-scope ytd-channel-about-metadata-renderer" href="mailto:undefined" hidden=""></a>
            </td>
          </tr>
          <tr class="style-scope ytd-channel-about-metadata-renderer">
            <td class="label style-scope ytd-channel-about-metadata-renderer">
              <yt-formatted-string class="style-scope ytd-channel-about-metadata-renderer"><span class="deemphasize style-scope yt-formatted-string"> Location:   </span></yt-formatted-string>
            </td>
            <td class="style-scope ytd-channel-about-metadata-renderer">
              <yt-formatted-string class="style-scope ytd-channel-about-metadata-renderer">YourCountry</yt-formatted-string>
            </td>
          </tr>
        </tbody></table>
      </div>

假设我需要获取 "YourCountry" 我实际上如何获取该元素？

到目前为止我试过：

  const location = await page.$$eval(
    "#details-container > table > tbody:nth-child(1) > tr:nth-child(1) > yt-formatted-string",
    locationEl => locationEl.innerHTML
  );
console.log(location) // Undefined

不知道该怎么做，尝试 return 只是 tr 然后再次评估 tr[1] 不起作用，因为它说 tr 没有函数 .$$eval。

请注意，我正在使用 apify 获取页面。

Answer 1

在您提供的 HTML 中，您想要的 yt-formatted-string 元素是第二个 td 下第二个 tr 的直接子元素，但您尝试来匹配它 yt-formatted-string，它是第二个 tr 的直接子代。您需要修复选择器。例如：

console.log("HTML:", document.querySelector("#details-container > table > tbody > tr:nth-child(2) > td:nth-child(2) > yt-formatted-string").innerHTML)

<div id="details-container" class="style-scope ytd-channel-about-metadata-renderer">
  <yt-formatted-string class="subheadline style-scope ytd-channel-about-metadata-renderer">Details</yt-formatted-string>
  <table class="style-scope ytd-channel-about-metadata-renderer">
    <tbody class="style-scope ytd-channel-about-metadata-renderer">
      <tr class="style-scope ytd-channel-about-metadata-renderer">
        <td class="label style-scope ytd-channel-about-metadata-renderer">
          <yt-formatted-string class="style-scope ytd-channel-about-metadata-renderer"></yt-formatted-string>
        </td>
        <td class="style-scope ytd-channel-about-metadata-renderer">
          <ytd-button-renderer align-by-text="" class="style-scope ytd-channel-about-metadata-renderer" button-renderer=""></ytd-button-renderer>
          <div id="captcha-container" class="style-scope ytd-channel-about-metadata-renderer"></div>
          <div id="email-container" class="style-scope ytd-channel-about-metadata-renderer"></div>
          <a id="email" target="_blank" class="style-scope ytd-channel-about-metadata-renderer" href="mailto:undefined" hidden=""></a>
        </td>
      </tr>
      <tr class="style-scope ytd-channel-about-metadata-renderer">
        <td class="label style-scope ytd-channel-about-metadata-renderer">
          <yt-formatted-string class="style-scope ytd-channel-about-metadata-renderer"><span class="deemphasize style-scope yt-formatted-string"> Location:   </span></yt-formatted-string>
        </td>
        <td class="style-scope ytd-channel-about-metadata-renderer">
          <yt-formatted-string class="style-scope ytd-channel-about-metadata-renderer">YourCountry</yt-formatted-string>
        </td>
      </tr>
    </tbody>
  </table>
</div>

和you should be able to call $$eval &c. if you have an ElementHandle。问题是你的选择器不匹配，所以你没有。

Answer 2

我更喜欢使用 jQuery。这是查询元素的最佳方式。例如，您可以从 Apify utils 注入 jQuery。

const { puppeteer } = Apify.utils;

await puppeteer.injectJQuery(page);
const location = await page. evaluate(() => {
  return $('#details-container yt-formatted-string').last().text();
});
console.log(location);

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