Socket.io (emit, on) not working - Node JS

Question

I am working on a node JS application, where I am trying to use socket.io following this tutorial. Until this tutorial everything is fine, even the client is connected to the server through the socket, as it display a message on connection. But I don't know why my code isn't working on emit, and on event, and event handler.

Below is my Code on server side :

const express = require("express"); const app = express(); const scrap = require("./algorithm"); const mysql = require("mysql"); const ms_connect = mysql.createConnection({ host:'localhost', user:'root', password:'', database:'scrapper_db' }); const server = app.listen(8000, function(){ console.log('Listening on 8000'); }); const io = require("socket.io").listen(server); app.use(express.static(__dirname + "/")); io.on("connection",function(socket){ console.log("Sockets Connection Made ! " + socket.id); socket.emit("testing",{data:"I am tested"}); io.on("disconnect",function(){ console.log("Client Disconnected !"); }) }) //mySQL Conection ms_connect.connect(function(err){ if(err) console.log(err); ms_connect.query("Select * FROM test",function(err,rows,fields){ if(err) console.log("Error Executing Query"); }) }) app.get("/scrap",function(req,res){ res.sendFile(__dirname+"/index.html"); })

Client side code :

var socket = io.connect('http://localhost:8000/scrap'); console.log(socket.connected); //returns false :( socket.on("testing", function(d) { console.log(d); });

In the client side, the socket.connected object returns false, but on server side it says connected. I don't know how , and I am using third link from this socket.io cdnjs server.

Why are you putting scrap on the client side? localhost:8000/scrap — Raphael Facredyn
– Raphael Facredyn, Commented Aug 8, 2018 at 19:59
This is the route for loading my index.html file from app.get("/scrap",func) @RaphaelFacredyn — Nadeem Ahmad
– Nadeem Ahmad, Commented Aug 8, 2018 at 20:02
You should try using socket.on('connect', () => { console.log(socket.connected); // true }); rather than just logging socket.connected Also what happens if you just use var socket = io.connect(); on your client side code — TommyBs
– TommyBs, Commented Aug 8, 2018 at 20:02

Raphael Facredyn · Accepted Answer · 2018-08-08 20:08:15Z

You are doing io.connect('http://localhost:8000/scrap') but the scrap is not mentioned anywhere on the server side. It should be io.connect('http://localhost:8000/'). Pointing to your HTML file is not needed because the socket.io server and your webserver are unrelated.

Also as pointed out by @TommyBs you should use

socket.on('connect', () => { console.log(socket.connected); });

to check if you are connected because connecting is asynchronous so it will not have connected yet by the time you do console.log(socket.connected);

The whole client code would be

var socket = io.connect('http://localhost:8000'); socket.on('connect', () => { console.log(socket.connected); }); socket.on("testing", function(d) { console.log(d); });

223seneca · Accepted Answer · 2018-08-08 20:00:44Z

Change http://localhost:8000/scrap to http://localhost:8000/ in the client code. You're connecting to the wrong route.

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