The core of the Ng-Busy module is an $http interceptor that keeps a tally of open HTTP requests, and fires an event when each request begins and ends. These events can be observed by your application or directives to determine whether or not the application busy.

busyInterceptor

Ng-Busy also provides a busy directive that observes these events from the interceptor and can modify the element when it transitions to busy, and then back again. A simple example is a Submit button that becomes disabled (to prevent repeat submissions) and the text changes to "Submitting..." while an HTTP request is issued, and then changes back to Submit when it completes.

busy directive