What’s happening is that your onError implementation in a Subscriber is throwing an unchecked exception which is against the Observable contract and this aborts the observable processing throwing an OnErrorFailedException in the observeOn scheduler.
In case myimage.gif isn’t transparent, you could use multiple backgrounds: background: url(‘myimage.gif’), url(‘fallback.gif’); This way fallback.gif will only be visible if myimage.gif isn’t available. Note that fallback.gif may be downloaded even if myimage.gif is available. Alternatively, even though not widely supported, CSS Images 3 introduces the image() notation: background: image(‘myimage.gif’, ‘fallback.gif’); Multiple <image-decl>s can be …
this is now possible in some browsers. The spec was updated to include the actual error with stacktrace as the 5th parameter. the problem is that not every browser supports this yet, so you could do something like this: window.onerror = function(message, filename, lineno, colno, error) { if(error != null) { //handle the error with …
window.onerror is not triggered when the console directly generates an error. It can be triggered via setTimeout though, e.g., setTimeout(function() { notThere(); }, 0); Possible duplicate: Chrome: Will an error in code invoked from the dev console trigger window.onerror?
This works: <img src=”https://stackoverflow.com/questions/8124866/invalid_link” onerror=”this.onerror=null;this.src=”https://placeimg.com/200/300/animals”;” > Live demo: http://jsfiddle.net/oLqfxjoz/ As Nikola pointed out in the comment below, in case the backup URL is invalid as well, some browsers will trigger the “error” event again which will result in an infinite loop. We can guard against this by simply nullifying the “error” handler via this.onerror=null;.
UPDATE 2021: All browsers today support onerror=”” on script tags, examples: Building script tag in js on MDN Html example by @Rudey in comments: <script src=”nonexistent.js” onerror=”alert(‘error!’)”></script> Original comment from 2010: If you only care about html5 browsers you can use error event. From the spec: If the src attribute’s value is the empty string …