How to track the sending of a message to the Bitrix24 chat?

Question

Bitrix24

How to track when a user sends a message to the Bitrix Chat widget? Tried this code - doesn't work. Site on Joomla

window.addEventListener('onBitrixLiveChat', function(event)
{
  var widgets = event.detail.widget;

  // Обработка событий 
  widgets.subscribe({
    type: BX.LiveChatWidget.SubscriptionType.userMessage,
    callback: function(data) {
      
    // любая команда
                    alert(1);
    }
  });
});