Websocket server: TypeError ws.send() not a function

Question

I'm starting to use node js. So far everything was good. Untill today. I was playing with websockets, i'm able to establish a connection between the server and the browser. However, I cannot send messages from the server to the client using ws.send('something'); In almost every example I can find the methode is used, and in my situation it doest not seem to work. Can somebody explain me why?

const express = require('express');
const path = require('path');
const WebSocket = require('ws').Server;
const router = express.Router();
const SerialPort = require('serialport');
const barCode = new SerialPort('COM50', {
    baudRate: 57600
  });

// --------- SETUP WS ---------
var wsport = 8085;
var ws = new WebSocket({port: wsport});

ws.on('connection', function open() {
  console.log('ws connection has been established.');
  // ws.send('something'); this line is not working!

});

// !!-- BarCode:: Log errors to console when they occur.
barCode.on('error', function(err) {
  console.log('Error: ', err.message); 
});

  barCode.on('data', function (data) {
    console.log('Barcode received:', data);
    ws.send('received barcode');
  });

// --------- SETUP EXPRESS ---------
var app = express();    // Define the application object
var port = 4000;        // Specify the port to listen to

router.get('/',function(req,res){
  res.sendFile(path.join(__dirname+'/public/index.html'));
  //__dirname : It will resolve to your project folder.
});

router.get('/offline',function(req,res){
  res.sendFile(path.join(__dirname+'/public/offline.html'));
  //__dirname : It will resolve to your project folder.
});

app.use(express.static('public'));
app.use('/', router);
app.listen(process.env.port || port);
console.log('Webserver running at port ' + port);

module.exports = app;

Answer 1

This is a very common mistake The thing here is the

var ws = new WebSocket({port: wsport});

ws.on('connection', function open() {
  console.log('ws connection has been established.');
  // ws.send('something'); this line is not working!
});

the variable created as an new Websocket, isn't valid inside the function

ws.on()

So as ws isn't a valid variable inside the function

ws.send() isn't a function, hence the error

Try calling another function inside ws.on(), that has the access to the variable ws where the object of the socket was created.

Answer 2

var ws_server = new WebSocket({ port: wsport });
ws_server.on('connection', (ws_socket) => {
    ws_socket.send('something'); 
});