I think that was a mistake. WHATWG still mention onerror in their HTML living standard specification. Also, onerror attribute on img elements is not included in their obsolete features list.
The way I solved this problem, is introducing a pure CSS fall-back, that older browsers that don’t support CSS calc would only read. figure.left { width: 48%; width: -webkit-calc(50% – 20px); width: -moz-calc(50% – 20px); width: calc(50% – 20px); } The left and right panels, get a width of 48% if the browser cannot read … Read more
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.
I set in config/application.rb usually config.i18n.fallbacks = [:de, :fr, :en] So you can declare the order of the fallback. But keep attention in some environments/*.rb the configuration is overwritten.
What you are looking for is something called PriorityBinding (#6 on this list) (from the article) The point to PriorityBinding is to name multiple data bindings in order of most desirable to least desirable. This way if the first binding fails, is empty and/or default, another binding can take it’s place. e.g. <TextBox> <TextBox.Text> <PriorityBinding> … Read more
Using except by itself will catch any exception short of a segfault. try: something() except: fallback() You might want to handle KeyboardInterrupt separately in case you need to use it to exit your script: try: something() except KeyboardInterrupt: return except: fallback() There’s a nice list of basic exceptions you can catch here. I also quite … Read more
To confirm that cdn script loaded you can check for existence any variable/function this script defines, if it is undefined – then cdn failed and you need to load local script copy. On this principle are based solutions like that: <script src=”https://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js”></script> <script>window.jQuery || document.write(‘<script src=”js/libs/jquery-1.5.1.min.js”>\x3C/script>’)</script> (if there is no window.jQuery property defined cdn script … Read more
A polyfill is a browser fallback, made in JavaScript, that allows functionality you expect to work in modern browsers to work in older browsers, e.g., to support canvas (an HTML5 feature) in older browsers. It’s sort of an HTML5 technique, since it is used in conjunction with HTML5, but it’s not part of HTML5, and … Read more