Headless browser not triggering onBeforeUnload event

Other Questions Headless Browser
1

I’m working on a web scraping project using Puppeteer with headless Chrome in Node.js. The issue I’m facing is that the onBeforeUnload event isn’t firing when navigating through pages in the headless browser, but it works fine in a regular browser.

Here’s what I’m doing:

  1. Navigating to a local website
  2. Scraping content and saving URLs
  3. Visiting each URL and processing the content

In my local website, I have an AJAX call set up on the onBeforeUnload event for every page:

$(window).on('beforeunload', function() {
  // AJAX call here
});

This works when browsing normally, but not in the headless browser. I’ve tested by moving the AJAX call to the DOMContentLoaded event, and it worked in the headless browser.

I’m wondering if there’s a way to ensure the AJAX call happens before leaving each page in both headless and normal browsers. Any ideas on how to achieve this or what event I could use instead?

2

I’ve encountered this issue before in my web scraping projects. One effective workaround is to intercept and handle navigation events directly in Puppeteer. You can use the page.on('beforeunload') method to execute your AJAX call before navigating away. This approach ensures consistency across both headless and regular browsers.

Another option is to implement a custom navigation method that triggers your AJAX call before moving to the next page. This gives you more control over the process and allows you to handle any potential errors or timeouts.

Remember to set a reasonable timeout for your AJAX calls to prevent hanging during navigation. These techniques have served me well in similar scenarios, providing reliable data collection while respecting the site’s intended behavior.

3

hey Alice, i had a similar issue. try using the unload event instead of beforeunload. it worked for me in both headless and regular browsers. also, make sure ur ajax call is synchronous to ensure it completes b4 the page unloads. hope this helps!

4

I’ve run into this headache before, mate. What worked for me was using the visibilitychange event instead. It’s more reliable across different browser setups, headless or not.

Here’s the gist:

document.addEventListener('visibilitychange', function() {
  if (document.visibilityState === 'hidden') {
    // Your AJAX call here
  }
});

This approach captures the moment right before the page is about to be hidden, ensuring your AJAX call gets executed. If you’re working with Puppeteer, consider using page.evaluate() to inject your script, which gives you additional control over the browser context. This method has consistently worked for me in similar scenarios, easing the scraping process.