Socket.io counter acknowledgement example

app.js

const app = require('express')();
const http = require('http').Server(app);
const io = require('socket.io')(http);

let counter = 0;

app.get('/', function(req, res){
  res.sendFile(__dirname + '/index.html');
});

io.on('connection', function(socket){
  socket.on('getCounter', function(callback) {
    // Increment the counter
    counter++;
  
    console.log(`Returning getCounter with counter ${counter}`);
    
    // Use a Node style callback (error, value)
    callback(null, counter);
  });
});

http.listen(3000, function(){
  console.log('listening on *:3000');
});

index.html

<script src="/socket.io/socket.io.js"></script>
<script>
  var socket = io();

  socket.emit('getCounter', function(error, counter) {
    console.log('Counter is', counter);
  });
</script>

hey

Hey,
Can I do the same in reverse order?. I mean, send emmit from server and execute callback on client?

Hey,
Can I do the same in reverse order?. I mean, send emmit from server and execute callback on client?

Yes you can