Simple AngularJS service using HTML5 Notifications API

angular.notifications.js

(function() {
    'use strict';

    var module = angular.module('jrl.notifications', []);

    module.service('notify', [
        '$q', '$window',
        function($q, $window) {
            var svc = {
                send: function(){},
                requestPermission: function(){},
                permission: null
            };

            // Let's only define stuff to do if we're inside of a 
            // context that actually supports HTML5 Notifications
            if("Notification" in $window) {
                svc.send = send;
                svc.requestPermission = requestPermission;
            }

            return svc;

            /**
             * Sends a notification to the user's desktop
             *
             * @param string title - Title of notification
             * @param string body - Body of notification
             * @param string icon - Notification icon url
             * @param string direction - One of 'ltr' or 'rtl'
             * @return void
             */
            function send(title, body, icon, direction) {
                direction = direction || 'ltr';

                if(!svc.permission) {
                    requestPermission.then(go);
                } else if(svc.permission !== 'denied') {
                    go();
                }

                function go() {
                    return new $window.Notification(title, {
                        body: body,
                        icon: icon,
                        dir: direction
                    });
                }
            }

            /**
             * Requests permission from the user to display HTML5 notifications
             *
             * @return promise - Resolved only if permission is granted
             */
            function requestPermission() {
                var defer = $q.defer();

                $window.Notification.requestPermission(
                    function(permission) {
                        svc.permission = permission;

                        if(permission === 'granted') {
                            defer.resolve();
                            return;
                        }

                        defer.reject();
                    }
                );

                return defer.promise;
            }
        }
    ]);
})();