Fallback image and timeout - External Content. Javascript

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.

Try to make use of the Image.complete property.

var img = new Image(w,h)
img.src = "http://...";

Now check periodically if img.complete is true and call some fallback mechanism shuold it still be false after n seconds.