Puppeteer selector failing to find elements on certain websites

Other Questions Puppeteer
1

I’m having trouble with Puppeteer when scraping data from some websites. The querySelector method keeps returning null for specific sites and I can’t figure out why. I’ve looked at similar issues online but none of the solutions worked for me. Here’s a sample of my code that doesn’t work as expected:

const puppeteer = require('puppeteer');

async function scrapePage() {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();

  await page.goto('https://example-store.com/product/cool-shirt');

  const priceElement = await page.evaluate(() => {
    return document.querySelector('.product-price');
  });

  console.log(priceElement);

  await browser.close();
}

scrapePage();

Can anyone help me understand why the selector might be failing on certain sites? Are there any tricks or alternative methods I should try?

2

I’ve been in your shoes, Claire. Sometimes websites can be tricky beasts when it comes to scraping. Have you considered that the element might be inside an iframe? I once spent hours debugging a similar issue only to realize the content was in a nested frame.

Another thing to watch out for is JavaScript-rendered content. Some sites load data asynchronously after the initial page load. In these cases, you might need to wait for the network to be idle or for a specific element to appear before trying to select it.

Also, double-check your selector. I’ve embarrassingly spent way too much time troubleshooting only to realize I had a typo in my class name. It might be worth using the browser’s dev tools to verify the selector is correct and present when the page loads.

If all else fails, you could try using XPath instead of CSS selectors. Sometimes they can be more reliable for complex page structures. Just a thought from my own scraping adventures!

3

I’ve encountered similar issues with Puppeteer selectors. One possibility is that the site you’re scraping uses dynamic content loading or has a complex DOM structure. Try adding a wait before querying the element:

await page.waitForSelector('.product-price', { timeout: 5000 });
const priceElement = await page.$('.product-price');

If that doesn’t work, the site might be using shadow DOM or iframes. In those cases, you might need to use more advanced selectors or even switch to using page.evaluate() with vanilla JavaScript to navigate the DOM structure.

Another thing to check is if the site is detecting and blocking scraping attempts. You could try setting a user agent string to mimic a regular browser:

await page.setUserAgent('Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.124 Safari/537.36');

Hope this helps point you in the right direction!