Node server, Socket.io 'io is not defined'?

Question

I\'ve followed the exact same steps which have always previously worked for me, create application through express, place the module dependencies in the node_modules folder.

Answer 1

Node.js newbie here! I am pretty sure this has been answered. Yet I kept finding problems with the src for the socket. Apparently this :

(Edit: although this is obvious, this link may not work depending on when you are reading this answer. Please pick the latest link from: https://cdnjs.com/libraries/socket.io)

Here is a working client side code:

On the server side (handles only 1 socket)

var app  = require('express')();
var http = require('http').Server(app);
var io   = require('socket.io')(http);
var port = process.env.PORT || 8080;


app.get('/', function(req, res){
    console.log("app works");
});

io.on('connection', function(socket){
    socket.emit('notification', {message:"hi"});
});

http.listen(port, function(){
    console.log('listening on :' + port);
});