How to Manage Dynamically Loaded File Input Fields in Puppeteer

Other Questions Puppeteer
1

I’m working on a project using Puppeteer and facing a challenge with interacting with multiple elements that are loaded dynamically after clicking an anchor link. I need to click on the second file upload input, but it’s not immediately visible after the click. Here’s what I’ve tried:

// Trigger content change by clicking the first anchor
await page.click('.file_pm a:first-of-type');

// Give the page some time to refresh
await page.waitForTimeout(2500); // Adjust time as necessary

// Confirm the file inputs are present
await page.waitForSelector('tbody input[type="file"]:nth-of-type(2)', { visible: true });

// Handle file selection for the first input
const uploadInput1 = await page.$('tbody input[type="file"]:nth-of-type(1)');
if (uploadInput1) {
    await uploadInput1.uploadFile(user.files[0].path);
} else {
    console.error('First file input not found.');
}

// Check again for the second input and upload
const uploadInput2 = await page.$('tbody input[type="file"]:nth-of-type(2)');
if (uploadInput2) {
    await uploadInput2.uploadFile(user.files[1].path);
} else {
    console.error('Second file input not found.');
}

// If needed, re-click the anchor tag
await page.click('.file_pm a:first-of-type');

Challenges:

After clicking the anchor, the second file input isn’t detected instantly. Even though I’ve put in longer wait times, the element seems active on-screen, yet my code fails to locate it. This situation appears to stem from the file inputs being loaded dynamically.

Inquiry:

  • How can I effectively manage Puppeteer to wait for elements that load dynamically post-action?
  • Is there a more dependable method to ascertain when new elements are ready for interaction?
  • What are the recommended practices for managing dynamic content updates with Puppeteer, especially concerning file inputs?

I would appreciate any guidance or recommendations!

2

Hi Grace, managing dynamic content with Puppeteer can be tricky, but there are strategies you can implement to handle these scenarios more effectively. Here’s a solution to help ensure your inputs are detected reliably:

Solution:

  • Use "waitForFunction": Instead of fixed timeout, leveraging Puppeteer’s page.waitForFunction can make your script more robust by explicitly checking if the element is visible and interactable.
    • 
  // Click to load new content
  await page.click('.file_pm a:first-of-type');

  // Wait for the second file input to be visible
  await page.waitForFunction(() => 
    document.querySelector('tbody input[type="file"]:nth-of-type(2)') && 
    document.querySelector('tbody input[type="file"]:nth-of-type(2)').offsetParent !== null,
    { timeout: 5000 } // Increase timeout if necessary
  );

  // Interact with the file inputs
  const uploadInput1 = await page.$('tbody input[type="file"]:nth-of-type(1)');
  const uploadInput2 = await page.$('tbody input[type="file"]:nth-of-type(2)');

  if (uploadInput1) {
    await uploadInput1.uploadFile(user.files[0].path);
  }

  if (uploadInput2) {
    await uploadInput2.uploadFile(user.files[1].path);
  }
  • Check for Loading States: If the content dynamically loads, check for any specific loading indicators on the page and wait for them to disappear before you proceed with interacting with the new elements.

    • By applying these methods, you can improve the reliability of your automation script in handling dynamic content updates.

    Hope this helps streamline your process!

3

Tackling dynamically loaded elements in Puppeteer requires a nuanced approach as loading times can vary. Here’s an alternate strategy to consider alongside the existing suggestions:

Advanced Strategies:

  • Implementation of Mutation Observers: Rather than relying solely on visibility checks, consider using Mutation Observers to detect changes in the DOM. This provides a more reactive approach to changes in dynamically loaded content.
    • 
  // Initialize mutation observer before interaction
  await page.evaluate(() => {
    const targetNode = document.querySelector('tbody');
    const config = { childList: true, subtree: true };

    // Callback function to execute when mutations are observed
    const callback = function(mutationsList) {
      for(let mutation of mutationsList) {
        if(mutation.type === 'childList') {
          console.log('A child node has been added or removed.');
        }
      }
    };
    
    const observer = new MutationObserver(callback);
    observer.observe(targetNode, config);
  });
  
  // Perform click to load content
  await page.click('.file_pm a:first-of-type');
  
  // Wait for the expected number of inputs indicating change
  await page.waitForFunction(() => {
    return document.querySelectorAll('tbody input[type="file"]').length >= 2;
  }, { timeout: 5000 });

  // Proceed to upload using the detected file inputs
  const inputs = await page.$$('tbody input[type="file"]');
  if(inputs[0] && inputs[1]) {
    await inputs[0].uploadFile(user.files[0].path);
    await inputs[1].uploadFile(user.files[1].path);
  }
  • Interaction Prioritization and Retry Logic: Implement a retry mechanism if initial interactions fail. This can help manage any sporadic loading behaviors by attempting the task again until the element is fully ready or a timeout is reached.

    • This combination of strategies allows you to manage script execution flow more effectively by leveraging real-time DOM event listening and retries, which enhance interaction consistency with dynamic elements.

    Let me know if you need further assistance or adjustments in your Puppeteer setup!