discourse/app/assets/javascripts/discourse/initializers/subscribe-user-notifications.js.es6

// Subscribes to user events on the message bus
import { init as initDesktopNotifications, onNotification } from 'discourse/lib/desktop-notifications';

export default {
  name: 'subscribe-user-notifications',
  after: 'message-bus',
  initialize(container) {
    const user = container.lookup('current-user:main'),
          site = container.lookup('site:main'),
          siteSettings = container.lookup('site-settings:main'),
          bus = container.lookup('message-bus:main');

    bus.callbackInterval = siteSettings.anon_polling_interval;
    bus.backgroundCallbackInterval = siteSettings.background_polling_interval;
    bus.baseUrl = siteSettings.long_polling_base_url;

    if (bus.baseUrl !== '/') {
      // zepto compatible, 1 param only
      bus.ajax = function(opts) {
        opts.headers = opts.headers || {};
        opts.headers['X-Shared-Session-Key'] = $('meta[name=shared_session_key]').attr('content');
        return $.ajax(opts);
      };
    } else {
      bus.baseUrl = Discourse.getURL('/');
    }

    if (user) {
      bus.callbackInterval = siteSettings.polling_interval;
      bus.enableLongPolling = true;

      if (user.get('staff')) {
        bus.subscribe('/flagged_counts', (data) => {
          user.set('site_flagged_posts_count', data.total);
        });
        bus.subscribe('/queue_counts', (data) => {
          user.set('post_queue_new_count', data.post_queue_new_count);
        });
      }

      bus.subscribe("/notification-alert/" + user.get('id'), function(data){
        onNotification(data, user);
      });

      bus.subscribe("/notification/" + user.get('id'), function(data) {
        const oldUnread = user.get('unread_notifications');
        const oldPM = user.get('unread_private_messages');

        user.set('unread_notifications', data.unread_notifications);
        user.set('unread_private_messages', data.unread_private_messages);

        if (oldUnread !== data.unread_notifications || oldPM !== data.unread_private_messages) {
          user.set('lastNotificationChange', new Date());
        }
      }, user.notification_channel_position);

      bus.subscribe("/categories", function(data) {
        _.each(data.categories,function(c) {
          site.updateCategory(c);
        });
      });

      if (!Ember.testing) {
        initDesktopNotifications(bus);
      }
    }
  }
};