How to call acknowledgment functions in SocketIO?

Server side

var io = require('socket.io')(8090);

io.on('connection', function (socket) {
  console.log('connected')
  socket.on('ferret', function (arg, ack) {
    console.log('ferret')
    ack('woot');
  });
});

Client side

const ioClient = require('socket.io-client');
var client = ioClient.connect('http://localhost:8090');
client.emit('ferret', 'tobu', (response) => {
  console.log(response)
  console.log('ack')
});

It will log the response of ack() and the 'ack' string. I got the reference socket.io acknowledge node.js sample.


Server

socket.on('foo', (arg) => {
//Do stuff with arg
    console.log('message from client : ' + data)
    socket.emit('bar','message acknowledge from server');
});

Client

socket.emit('foo', 'mymessage');
socket.on('bar', (data) => {
    console.log(data)
});

using socket.io in server side and socket.io-client in client side

Server side

var app = require('http').createServer();
var io = require('socket.io')(app);

app.listen(80);

io.on('connection', function (socket) {
    socket.emit('news', { hello: 'world' }, function(res) {
        console.log(res);
    });
});

Client side

var io = require('socket.io-client');

var socket = io('http://localhost');
socket.on('news', function (data, ack) {
    console.log(data);
    if(ack){
        ack("acknowledge from client");
    }
});

This issue usually occurs when you have a mismatch between the socket.io version and socket.io.js version. That is one scenario in which I was able to reproduce the ack being undefined.

Other I just tested it with Socket 2.04 and it works fine.

index.js

var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var port = process.env.PORT || 3000;
var host = process.env.HOST || "0.0.0.0";

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

app.get('*', function (req, res) {
  console.log(' request received ', req.headers.host);
  res.status(200).send();
});

io.on('connection', function(socket){
  socket.on('chat message', function(msg){
    io.emit('chat message', msg);
  });

socket.on('ferret', function (name, fn) {
    console.log('name', name, 'fn', fn);
    fn('tarun');
  });
});

http.listen(port,host, function(){
  console.log('listening on *:' + port);
  console.log('Env name is ' + process.env.name)
});

index.html

<!doctype html>
<html>
  <head>
    <title>Socket.IO chat</title>
    <style>
      * { margin: 0; padding: 0; box-sizing: border-box; }
      body { font: 13px Helvetica, Arial; }
      form { background: #000; padding: 3px; position: fixed; bottom: 0; width: 100%; }
      form input { border: 0; padding: 10px; width: 90%; margin-right: .5%; }
      form button { width: 9%; background: rgb(130, 224, 255); border: none; padding: 10px; }
      #messages { list-style-type: none; margin: 0; padding: 0; }
      #messages li { padding: 5px 10px; }
      #messages li:nth-child(odd) { background: #eee; }
      #messages { margin-bottom: 40px }
    </style>
  </head>
  <body>
    <ul id="messages"></ul>
    <form action="">
      <input id="m" autocomplete="off" /><button>Send</button>
    </form>
    <script src="/socket.io/socket.io.js"></script>
    <script src="https://code.jquery.com/jquery-1.11.1.js"></script>
    <script>
      $(function () {
        var socket = io();
socket.on('connect', function () { // TIP: you can avoid listening on `connect` and listen on events directly too!
    socket.emit('ferret', 'tobi', function (data) {
      console.log(data); // data will be 'woot'
    });
  });
        $('form').submit(function(){
          socket.emit('chat message', $('#m').val());
          $('#m').val('');
          return false;
        });
        socket.on('chat message', function(msg){
          $('#messages').append($('<li>').text(msg));
          window.scrollTo(0, document.body.scrollHeight);
        });

      });
    </script>
  </body>
</html>

package.json

{
  "name": "socket-chat-example",
  "version": "0.0.1",
  "description": "my first socket.io app",
  "dependencies": {
    "express": "^4.15.2",
    "socket.io": "^2.0.4"
  },
  "scripts": {
    "start": "node index.js"
  }
}

Working

Tags:

Javascript

Node.Js

Socket.Io

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