The HTML onerror attribute is an event handler that triggers the execution of a script when an error occurs while loading an external resource
Definition and Usage
➔ It is typically used to handle broken links to images, scripts, or media files.
➔ The primary purpose is to provide a nice fallback or log errors when a resource fails to load, which improves the user experience.
➔ The window.onerror event handler can capture common, elusive JavaScript runtime errors throughout the page and provides error messages and the reason for the failure.
Example
<img src="notexist.jpg" onerror="this.onerror=null; this.src='fallback.jpg';">
<!-- This line shows a common practice that prevents
infinite loops even if the fallback image is not loaded. -->