Detect if the iframe content has loaded successfully

Question

I have a widget that contains an iframe. The user can configure the url of this iframe, but if the url could not be loaded (it does not exists or the user does not have acce

Answer 1

I found the following link via Google: http://wordpressapi.com/2010/01/28/check-iframes-loaded-completely-browser/

Don't know if it solves the 'Page Not Found' issue.

I haven't tried it myself, so I don't know if it works. Good luck!