express-ws: "ws.send is not a function" - node.js

Question

I'm creating an App using Node.js + Express + Express-ws, but I'm getting the following error when I try to send a message after connection:
const fs = require('fs');
const http = require('http');
const https = require('https');
const express = require('express');
const app = express();
/*
const key = fs.readFileSync('./security/server-key.pem', 'utf8');
const cert = fs.readFileSync('./security/server-crt.pem', 'utf8');
const ca = fs.readFileSync('./security/ca-crt.pem', 'utf8');
const credentials = {key: key, cert: cert, ca: ca};
var httpsServer = https.createServer(credentials, app);
*/
var httpServer = http.createServer(app);
httpServer.listen(8443, function(){
console.log('Listening on *:8443 \n');
});
httpServer.on('connection', function(ws) {
ws.on('message', function(message) {
console.log('received: ' + message);
ws.send(message);
});
ws.send('Hi there, I am a WebSocket server');
});
//ROUTES
app.get('/charger/:id', function(req, res){
res.send('<h1>Hello ' + req.params.id + '</h1>');
});
app.get('*', function(req, res){
res.status(404).send('404 — Not Found');
});
The commented part is to verify that I can use later HTPPS without changint too much stuff.
The error is the following:
TypeError: ws.send is not a function
at Server.<anonymous> (index.js:26:5)
at Server.emit (events.js:194:15)
at TCP.onconnection (net.js:1517:8)

Answer 1

From what I can tell, it's because you're not actually using the express-ws package anywhere. Additionally, the httpServer object is an instance of the http.Server class, and has no built-in knowledge of websockets. Even though you call the argument in the callback ws, it's not actually a websocket object -- it's an instance of the http.ClientRequest class, which has no send method, hence the ws.send is not a function error. So, to resolve this, I think you'll need to do something along these lines, per the docs:
const express = require('express');
const app = express();
const expressWs = require('express-ws')(app);
app.ws('/', function(ws, req) {
// Now you have a ws object available
})
Hope that helps, good luck!