[AngularJS] Design Pattern: Simple Mediator

We're going to use rootScope emit here to send out events and then we're going to listen for them in the run block. We're going to use rootScope on down in the run block to listen for the same event that we sent out to the system.

angular
    .module('app', [])
    .controller('MainCtrl', function($scope, Order) {
        $scope.newOrder = function() { new Order(); };
    })
    .factory('Order', function($emit) {
        function Order() {
            this.email   = '[e-mail]';
            this.product = 'Macbook Pro';
            $emit('order:created', this);
        }
        return Order;
    })
    .factory('$emit', function($rootScope) {
        return function() { $rootScope.$emit.apply($rootScope, arguments); };
    })
    .factory('Email', function($window) {
        function Email(text) {
            $window.alert(text);
        }
        return Email;
    })
    .run(function($rootScope, Email) {
        $rootScope.$on('order:created', function(event, order) {
            new Email('Email sent to ' + order.email + ' for ' + order.product);
        });
    });

We don't want ot inject $rootscope into Order factry, so we use mediator to create a $emit() function, and each time we create a new order, it will send the create event to run block. isnide the run block we send the email. This is good because, the order doesn't know the Email event, it onlys emits a create event.