Q: socket.io client making 2 connections I've tried using the options mentioned on socketio's website to increase the time before reconnection, disabling connection upgrade from http to websocket, enabling the forceNew option. But there's always 2 connections whenever the client page loads.
Anyone has any idea on what is going on. I'm eager to give more information if required. Thank you for reading this.
Client Code( React.js + TailwindCSS )
import "./App.css";
import { io } from "socket.io-client";
import Home from "./pages/Home/Home";

function App() {
  const socket = io("http://localhost:3000/");
  socket.on("connect", () => {
    console.log(socket.id);
    console.log(socket.connected);
  });
  return (
    <div className="App">
      <Home />
    </div>
  );
}

Server Code (Node.js)
import http from "http";
import { Server } from "socket.io";
import express from "express";

const app = express();
const server = http.createServer(app);
const io = new Server(server, {
  cors: {
    origin: "http://localhost:3001",
    methods: ["GET", "POST"],
  },
});

io.on("connection", (client) => {
  console.log("client connected", client.id);
  client.on("event", (data) => {});
  client.on("disconnect", () => {});
});

server.listen(3000);
server.on("listening", () => console.log("listening"));


Client Console
2zcCMTkpbDtW-R5jAAA-
true
KdzGTWRxUIhlk0bKAAA_
true

Server Console
listening
client connected zh1zj5dnUb55zUdrAAAB
client connected rQexCoY7B6Es_r_RAAAD



A: You need to initiate the socket inside a useEffect hook, otherwise, it will run each time your component rerenders.
In this case, io function will trigger only once, since the useEffect has no dependencies, it will run one time only. Also, make sure to close the connection once your App is unmounted
function App() {
  const [socket, setSocket] = useState(null);

  useEffect(() => {
    const s = io("http://localhost:3000/");
    setSocket(s);

    return () => s.disconnect();
  }, [setSocket]);

  return (
    <div className="App">
      <Home />
    </div>
  );
}

