deferred.catch() 3.0 A function that is called when the Deferred is rejected. Add handlers to be called when the Deferred object is rejected.

deferred.catch( fn ) is an alias to deferred.then( null, fn ). Read its page for more information.

 Since the jQuery.get method returns a jqXHR object, which is derived from a Deferred object, we can add rejection handlers using the .catch method.