Fixing MultiEvent Listener in Zeppelin

There was an annoying bug in zeppelin:

After moving from one note to another, Running the whole note, or adding new paragraph in a note would be done X times.

There is a simple reason related to angularJs: We have overused $rootScope.$on.

When a $rootScope.$on (Event Listener) is registered, it is registered with the $rootScope. Which means that even if the Controller was flushed after a changing page, the $rootScope is not destroy and the event listener is still register for the old Controller.

How to Use Events in AngularJS/Zeppelin

• $rootScope.$on event listeners should only be used in MainCtrl which is the top of the App.
• Use $scope.$on for every other controllers to listen to Events
• Use $scope.$emit to send an event to a parent Controller (for example: paragraphCtrl to notebookCtrl)
• Use $scope.$broadcast to send an event to a child Controller (for example: notebookCtrl to paragraphCtrl)
• Use $rootScope.$emit to send an event to a controller that is not your parent (for example: paragraphCtrl to navCtrl), this event should be catch by the MainCtrl with a $rootScope.$on, then sent back to the rightful receiver using $scope.$broadcast.

Current ControllerStructure

MainCtrl: {
    NavCtrl,
    NotebookCtrl: [ paragraphCtrl, ...]
}