A method for using $rootScope as a global events bus. Currently leaky: need to delete events after deregistration.

angular-event-bus.js

app.service('AppEvents', [
    '$rootScope', '$log',
    function ($rootScope, $log) {

        // Store for callback functions.
        this._events = {};

        // Deregister an event.
        var deregister = function (offFunc) {
            if (offFunc) {
                offFunc();
                return true;
            }
            return false;
        };

        // Store the deregistration function mapped to the handler and name.
        this.on = function (name, handler) {
            var offFunc = $rootScope.$on.apply($rootScope, arguments);
            if (!this._events[name]) {
                this._events[name] = {};
            }
            this._events[name][handler.toString()] = offFunc;
        };

        // Deregister a single event by its name and handler, all events for
        // a given name, or all events ever registered.
        this.off = function (name, handler) {
            var success = true;
            if (handler && name) {
                // Remove just one event by the handler.
                var handlerString = handler.toString();
                if (!this._events[name] || !this._events[name][handlerString]) {
                    success = false;
                } else {
                    var offFunc = this._events[name][handlerString];
                    success = deregister(offFunc);
                }
            } else if (name) {
                // Remove all events under a name.
                var hasLooped = false;
                angular.forEach(this._events[name], function (offFunc) {
                    hasLooped = true;
                    var removed = deregister(offFunc);
                    if (!removed) {
                        success = false;
                    }
                });
                if (!hasLooped) {
                    success = false;
                }
            } else {
                // Remove all events.
                angular.forEach(this._events, function (savedEventObj, name) {
                    angular.forEach(savedEventObj, function (offFunc) {
                        var removed = deregister(offFunc);
                        if (!removed) {
                            success = false;
                        }
                    });
                });
            }
            // Warn if event removal was unsuccessful.
            if (!success) {
                $log.warn('Cannot deregister ' + name);
            }
        };

        // Trigger an event. This passes straight through to $rootScope.
        this.trigger = function () {
            $rootScope.$emit.apply($rootScope, arguments);
        };

    }
]);

// Somewhere in an Angular thing with AppEvents injected.
AppEvents.on('whatHasHappened', function ($event, thing) {
    console.log(thing + ' has happened');
});
AppEvents.trigger('whatHasHappened', 'nothing');
// 'nothing has happened'

// Remove events.
AppEvents.off('whatHasHappened');
// Optionally pass the handler for greater specificity, or pass no
// parameters to remove all events.