Not able to connect socket.io in nodejs - node.js

Question

Hi I am trying to setup a connection with socket.IO but not able to do so. At present I am not getting any error but the connection is not taking place.Please find below the relevant details :
app.js
const express = require('express');
require('./db/mongoose');
const functions = require("firebase-functions");
var bodyParser = require('body-parser');
const app = express();
const http = require('http').createServer(app);
var io = require('socket.io');
socket = io(http, {cors: {
origin: "http://localhost",
methods: ["GET", "POST"]
}
});
var cors = require("cors");
var cookieParser = require('cookie-parser');
var path = require('path');
app.use(cors());
const portCheck = process.env.PORT || 3001
socket.on('connection', function (socket) {
console.log('connected to socket');
socket.emit('greeting-from-server', {
greeting: 'Hello Client'
});
});
app.listen(portCheck, ()=> {
console.log('Server Listening to port:' + portCheck);
})

Answer 1

Changes should done for your code as follows:
Change app listen with server listen
wrap socket.on(//...) with io.on(//...)
replace this lines
const app = express();const http =
require('http').createServer(app);
with
var server = require('http').Server(app);
var io = require('socket.io')(server);
After the changes code is like follows.
const express = require('express');
require('./db/mongoose');
const functions = require("firebase-functions");
var bodyParser = require('body-parser');
const app = express();
var server = require('http').Server(app);
var io = require('socket.io')(server);
socket = io(http, {cors: {
origin: "http://localhost",
methods: ["GET", "POST"]
}
});
var cors = require("cors");
var cookieParser = require('cookie-parser');
var path = require('path');
app.use(cors());
const portCheck = process.env.PORT || 3001
server.listen(portCheck, ()=> {
console.log('Server Listening to port:' + portCheck);
})
io.on('connection', (socket)=> {
socket.on('connection', function (socket) {
console.log('connected to socket');
socket.emit('greeting-from-server', {
greeting: 'Hello Client'
});
});
});
follow more information through this link. https://socket.io/get-started/chat.