Why Web Socket Behave Differently On Nodejs ?

I have a Nodejs Server.js code : first Concept : var http = require('http'); var express = require('express'); var app = express(); var path = require('path'); var conn= http.cr

Solution 1:

To specifically answer your question: why web socket behave differently on nodejs? the answer is: It shouldn't. In the second version of your code you are not serving any HTML or JS files to the client on the port 3000 so the browser can't download any HTML.

If you want it to work as expected then you need to serve some HTML and JS files to the browser that visits http://localhost:3000/ or otherwise it will not be able to connect.

I wrote some example code - both server-side and client-side - on how to use WebSocket to do exactly what you are trying to do here. It's available on GitHub and I originally wrote it for this answer: Differences between socket.io and websockets.

The relevant parts of the source code for your question here are:

WebSocket Server

WebSocket server example using Express.js:

var path = require('path');
var app = require('express')();
var ws = require('express-ws')(app);
app.get('/', (req, res) => {
  console.error('express connection');
  res.sendFile(path.join(__dirname, 'ws.html'));
});
app.ws('/', (s, req) => {
  console.error('websocket connection');
  for (var t = 0; t < 3; t++)
    setTimeout(() => s.send('message from server', ()=>{}), 1000*t);
});
app.listen(3001, () =>console.error('listening on http://localhost:3001/'));
console.error('websocket example');

Source: https://github.com/rsp/node-websocket-vs-socket.io/blob/master/ws.js

WebSocket Client

WebSocket client example using vanilla JavaScript:

var l = document.getElementById('l');
var log = function (m) {
    var i = document.createElement('li');
    i.innerText = newDate().toISOString()+' '+m;
    l.appendChild(i);
}
log('opening websocket connection');
var s = newWebSocket('ws://'+window.location.host+'/');
s.addEventListener('error', function (m) { log("error"); });
s.addEventListener('open', function (m) { log("websocket connection open"); });
s.addEventListener('message', function (m) { log(m.data); });

Source: https://github.com/rsp/node-websocket-vs-socket.io/blob/master/ws.html

Instead of debugging a code that it not working, sometimes it's better to start from something that works and go from there. Take a look at how it all works and feel free to change it and use it in your projects - it's released under MIT license.