Advanced Node.js Development

Updating the event emitter

To send acknowledgement d=from server to client, we're going to add a third argument which is going to be a callback function. This function is going to fire when the acknowledgement arrives at the client, and we can do anything we like. For now we'll just print using console.log('Got it'):

socket.emit('createMessage', { 
  from: 'Frank', 
  text: 'Hi' 
}, function () { 
  console.log('Got it'); 
}); 

Now this is all we need to do bare-bones style to add an acknowledgement to the client.