wekan/client/components/notifications/notifications.jade

template(name='notifications')
  #notifications.board-header-btns.right
    a.notifications-drawer-toggle.fa.fa-bell(class="{{#if $gt unreadNotifications 0}}alert{{/if}}" title="{{_ 'notifications'}}")
    if $.Session.get 'showNotificationsDrawer'
      +notificationsDrawer(unreadNotifications=unreadNotifications)