By default, Knockout's enable (and hence disable binding, since they share identical but opposite logic) simply set/remove the disabled attribute. While this work's great with Bootstrap 3's <button />-type elements, it doesn't go so well when using the alternative <a role='button' /> syntax.

The problem is that Bootsrap expects an additional disabled class when disabling <a/> elements, which Knockout doesn't add by default. We can remedy this by enhancing the core enable binding like so:

This additional logic will toggle the appropriate disabled class on all elements with a btn class when bound with the enable or disable bindingHandler.