Socket.io doesn't work with on event ("connection") - node.js

Question

i want to use socket-io in my project and i established it on the server (node-js) and
the client (react) but it seems doesn't work fine and in console on the server i can't see user connected when user connected.
app.js (server):
const express = require("express");
const app = express();
const PORT = process.env.PORT || 5000;
(async () => {
await mongoConnect(error => {
if (error) {
console.log(error);
} else {
const server = app.listen(PORT, () =>
console.log(`server is running on ${PORT} port`)
);
const io = require("./utils/socket-io/socket-io").initialSocket(server);
io.on("connection", socket => {
console.log("user connected");
});
}
});
})();
socket-io.js (server):
const socketIo = require("socket.io");
let io;
module.exports = {
initialSocket: server => {
io = socketIo(server);
return io;
},
getIo: () => {
if (!io) {
throw new Error("no connection to socket-io");
}
return io;
}
};
posts.js (client):
import socketIo from "socket.io-client";
useEffect(() => {
socketIo("http://localhost:5000");
}, [socketIo]);

Answer 1

Edit your app.js to this
const http = require('http');
const socketio = require('socket.io');
const app = express();
const server = http.createServer(app); // This is going to allow us to create a new web server for express and we're going to it to our express application
const io = socketio(server); // Configure socketio to work with a given server
// Now the server supports websockets
(async () => {
await mongoConnect(error => {
...
else {
io.on("connection", socket => {
console.log("user connected");
});
server.listen(port, () => console.log(`Server is up on port ${port}`));
}
});
})();