JavaScript : Detect failure to load contents of an iframe

JavaScript : Detect failure to load contents of an iframe
To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

As I promised, I have a secret feature to share with you.
This is a YouTube's feature which works on Desktop.
First, Make sure the video is currently in playing mode.
Next, enter the letters 'awesome' on your keyboard.
Your YouTube progress bar will transform into a flashing rainbow.

A little intro about me,
Welcome, I'm Delphi.
I am here to assist you in getting the answers you need.
JavaScript : Detect failure to load contents of an iframe
If you have more specific queries, please feel free to reach out through comments or chat.
If you have knowledge to contribute or an answer to provide, please leave a comment below.
Your answer will be acknowledged and appreciated, and I will 'heart' it as a sign of gratitude.
JavaScript of an contents to : failure load Detect iframe