Widget causes browser warning: "Unload event listeners are deprecated" from fbevents.js

Hi everyone,

I'm using the Calendly inline widget on my website and I'm consistently seeing this deprecation warning in my browser's developer console:

Unload event listeners are deprecated and will be removed.

1 source

fbevents.js:196

🔍 Investigation

After investigating, I confirmed:

• The warning comes from Facebook Pixel (

  fbevents.js

  ) which is loaded by the Calendly widget
• My website has no Facebook Pixel code—this is entirely from Calendly's widget script (

  assets.calendly.com/assets/external/widget.js

  )

⚠️ Why This Matters

Modern browsers (Chrome, Edge, Firefox) are deprecating 

unload

 event listeners because they:

1. Block the back-forward cache (bfcache) → Slower navigation
2. Hurt Core Web Vitals / Lighthouse scores → Lower "Best Practices" rating
3. Are unreliable on mobile → May not fire at all

Google Chrome is planning to fully remove support for 

unload

 events in the near future.

✅ Suggested Fix

Facebook's 

fbevents.js

 should migrate to using:

• pagehide

   event

• visibilitychange

   event

These are the modern, recommended alternatives.

📋 My Setup

• Widget type: Inline widget
• Browser: Chrome (latest)
• Widget embed: Standard script from Calendly

🙏 Request

Could the Calendly team please update the Facebook Pixel integration to use modern event listeners? This would improve performance for all embedded widgets.

Has anyone else noticed this warning? Would love to know if there's a workaround or if this is already on the roadmap.

Thanks! 🚀