discourse/app/assets/javascripts/discourse/initializers/subscribe_user_notifications.js

/**
  Updates the relative ages of dates on the screen.

**/
Discourse.addInitializer(function() {

  var user = Discourse.User.current();
  if (user) {
    var bus = Discourse.MessageBus;
    bus.callbackInterval = Discourse.SiteSettings.polling_interval;
    bus.enableLongPolling = true;
    bus.baseUrl = Discourse.getURL("/");

    if (user.admin || user.moderator) {
      bus.subscribe("/flagged_counts", function(data) {
        user.set('site_flagged_posts_count', data.total);
      });
    }
    bus.subscribe("/notification/" + user.get('id'), (function(data) {
      user.set('unread_notifications', data.unread_notifications);
      user.set('unread_private_messages', data.unread_private_messages);
    }), user.notification_channel_position);

    bus.subscribe("/categories", function(data){
      var site = Discourse.Site.current();
      _.each(data.categories,function(c){
        site.updateCategory(c);
      });
    });
  }

}, true);