AngularJS Factory and Observer Pattern

HTML

<div ng-app="app" ng-controller="testController">
    <div ng-repeat="notification in notifications">{{notification}}</div>
</div>

JavaScript

angular.module('app', [])
    .factory('TestService', function () {
    var _subscribers = [];

    setInterval(function () {
        // every 1 second, notify all subscribers
        console.log(_subscribers);
        angular.forEach(_subscribers, function (cb) {
            cb('tester special @ ' + new Date());
        });
    }, 5500);

    return {
        subscribe: function (cb) {
            _subscribers.push(cb);
        }
    };
})
    .controller('testController', function ($scope, TestService) {
    $scope.notifications = ['nothing yet'];

    TestService.subscribe(function (notification) {
        $scope.$apply(function () {
            $scope.notifications.push('got  ' + notification);
        });
    });
});