[javascript] how to get session id of socket.io client in Client

I want to get session id of client in my socket.io client.

here is my socket.io client :

var socket = new io.Socket(config.host, {port: config.port, rememberTransport: false});
    // when connected, clear out display
    socket.on('connect',function() {
        console.log('dummy user connected');
    });
    socket.on('disconnect',function() {
        console.log('disconnected');
    });
    socket.connect();
    return socket;

I want to get session id of this client , how can i get that ?

For some reason

socket.on('connect', function() {
    console.log(socket.io.engine.id);
}); 

did not work for me. However

socket.on('connect', function() {
    console.log(io().id);
}); 

did work for me. Hopefully this is helpful for people who also had issues with getting the id. I use Socket IO >= 1.0, by the way.

Try this way.

                var socket = io.connect('http://...');
                console.log(socket.Socket.sessionid);

Try from your code socket.socket.sessionid ie.

    var socket = io.connect('http://localhost');
alert(socket.socket.sessionid);
  var sendBtn= document.getElementById('btnSend');
  sendBtn.onclick= function(){
var userId=document.getElementById('txt1').value;
var userMsg = document.getElementById('txt2').value;
socket.emit('sendto',{username: userId, message: userMsg});
};

  socket.on('news', function (data) {
    console.log(data);
    socket.emit('my other event', { my: 'data' });
  });
  socket.on('message',function(data){ console.log(data);});

On Server side

io.on('connection', socket => {
    console.log(socket.id)
})

On Client side

import io from 'socket.io-client';

socket = io.connect('http://localhost:5000');
socket.on('connect', () => {
    console.log(socket.id, socket.io.engine.id, socket.json.id)
})

If socket.id, doesn't work, make sure you call it in on('connect') or after the connection.

On socket.io >=1.0, after the connect event has triggered:

var socket = io('localhost');
var id = socket.io.engine.id

I just had the same problem/question and solved it like this (only client code):

var io = io.connect('localhost');

io.on('connect', function () {
    console.log(this.socket.sessionid);
});

* Please Note: as of v0.9 the set and get API has been deprecated *

The following code should only be used for version socket.io < 0.9
See: http://socket.io/docs/migrating-from-0-9/

It can be done through the handshake/authorization mechanism.

var cookie = require('cookie');
io.set('authorization', function (data, accept) {
    // check if there's a cookie header
    if (data.headers.cookie) {
        // if there is, parse the cookie
        data.cookie = cookie.parse(data.headers.cookie);
        // note that you will need to use the same key to grad the
        // session id, as you specified in the Express setup.
        data.sessionID = data.cookie['express.sid'];
    } else {
       // if there isn't, turn down the connection with a message
       // and leave the function.
       return accept('No cookie transmitted.', false);
    }
    // accept the incoming connection
    accept(null, true);
});

All the attributes, that are assigned to the data object are now accessible through the handshake attribute of the socket.io connection object.

io.sockets.on('connection', function (socket) {
    console.log('sessionID ' + socket.handshake.sessionID);
});

Have a look at my primer on exactly this topic.

UPDATE:

var sio = require('socket.io'),
    app = require('express').createServer();

app.listen(8080);
sio = sio.listen(app);

sio.on('connection', function (client) {
  console.log('client connected');

  // send the clients id to the client itself.
  client.send(client.id);

  client.on('disconnect', function () {
    console.log('client disconnected');
  });
});