Chapter 5: Building an event bus

by billy roberts

HTML

<script src="https://code.angularjs.org/1.3.2/angular.min.js"></script>
<div ng-app="myApp">
    <div ng-controller="Ctrl">
        <button ng-click="generateEvent()">Generate event</button>
    </div>
    <div my-dir></div>
</div>

JavaScript

//TOTALLY CLEAN PUB/SUB - implicitly add the pub/sub util to all
// scopes by decorating rootScope

angular.module('myApp',[])
.config(function($provide){
    $provide.decorator('$rootScope', function($delegate){
        // adds to the constructor prototype to allow use in isolate scopes
        var proto = $delegate.constructor.prototype;
        
        proto.subscribe = function(event, listener) {
            var unsubscribe = $delegate.$on(event, listener);
            this.$on('$destroy', unsubscribe);
        };
        
        proto.publish = function(event, data) {
            $delegate.$emit(event, data);
        };
        
        return $delegate; 
    });
})
.controller('Ctrl',function($scope, $log) {
    $scope.generateEvent = function() {
        $scope.publish('busEvent');
    };
    
    $scope.subscribe('busEvent', function() {
        $log.log('Handler called!');
    });
})
.directive('myDir', function($log) {
    return {
        scope: {},
        link: function(scope, el, attrs) {
            scope.subscribe('busEvent', function() {
                $log.log('Handler called!');
            });
        }
    };
});