How to check the lack of Internet and show a stub?

Question

React

Hello. I have an iframe in my project, when I turn off the Internet and go to the page with the iframe, I just get the error "Failed to open the web page (see
screenshot)

Answer 1

https://www.npmjs.com/package/react-detect-offline
try this

Answer 2

Presumably like this:
https://developer.mozilla.org/en-US/docs/Web/API/N...

if (navigator.onLine) {
  console.log('online');
} else {
  console.log('offline');
}

Answer 3

Google towards onLoad and onError in the JS reference .