code: function subscribeToChat () {
    console.tron.log('Subscribing to Chat')
    if (!subscriptions.hasOwnProperty('chat')) {
      subscriptions.chat = { subscribed: true }
      connection.then(() => {
        chatSubscriber = stompClient.subscribe('/topic/chat', onMessage.bind(this, 'chat'))
      })
    }
  }
docs: methods for subscribing