Puppeteer gives undefined with $$eval

October 30, 2022

So, I’m trying to scrape web in order to get their elements link as well as id. However, it throws me an undefined as a result. I know that these classes exist because I use page.evaluate, which gets specified class without hesitation. Cannot figure out why it is not working. Moreover, it looks like, that the console.log is not being printed too

  const flats = await page.$$eval(".result-item-v3", (elements) => {
    console.log(elements.length);
    return elements.forEach((element) => {
      return {
        link: element.querySelector(".object-image-link").getAttribute("href"),
        id: element.attributes.id.value,
      };
    });
  });

  console.log(flats);

This part works like a charm with exact same class:

        const flatsHashId = await newPage.evaluate(() =>
          [...document.querySelectorAll(".result-item-v3")].map(
            (elem) => elem.attributes.id.value
          )
        );

>Solution :

Just change forEach method to map method. forEach method doesn’t return a new transformed array, instead it returns undefined.

Like this:

const flats = await page.$$eval(".result-item-v3", (elements) => {
  console.log(elements.length);
  return elements.map((element) => {
    return {
      link: element.querySelector(".object-image-link").getAttribute("href"),
      id: element.attributes.id.value,
    };
  });
});

console.log(flats);