Question

What is the best way to set up a local fallback image if the external image does not load or takes too long to load.

Answer 1

You can add an onerror handler:

<img
  src="http://example.com/somejpg.jpg"
  onerror='this.onerror = null; this.src="./oops.gif"'
/>

Note: Setting onerror to null in the handler, so that the webpage doesn’t crash if oops.gif can’t be loaded for some reason.