Pure WebSocket Node.js Server using Native HTTP Module

websocket-client.js

// make a request
const options = {
    port: 1337,
    host: 'localhost',
    headers: {
        'Connection': 'Upgrade',
        'Upgrade': 'websocket'
    }
};
const protocol = 'http'
// if your protocol is https you will need to require https module instead of http
const http = require(protocol)
const req = http.request(options);
req.end();

req.on('upgrade', (res, socket, upgradeHead) => {
    console.log('got upgraded!');
    socket.on('data', data => {
        console.log('client received', data.toString())
    })
    
    // keep sending messages
    setInterval(() => {
        socket.write('Hello!')
    }, 500)
    
});

websocket-server.js

const http = require('http');
const port = 1337


// when curl http:localhost://1337
const server = http.createServer((req, res) => {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('hey there');
});

server.on('upgrade', (req, socket, head) => {
    const id = Date.now()
    const headers = [
        'HTTP/1.1 101 Web Socket Protocol Handshake',
        'Upgrade: WebSocket',
        'Connection: Upgrade',
        ''
    ].map(line => line.concat('\r\n')).join('')

    socket.write(headers);
 
    socket.on('data', data => {
        console.log('server!', data.toString());
        socket.write(`replying ${data.toString()} ${new Date().toISOString()}`)
    });

    socket.on('end', _ => { console.log(`${id} disconnected!`) })

});

// Now that server is running
server.listen(port, () => console.log('server runnig at', port));

It should be borne in mind that several websocket frames may arrive in the buffer, and the last of them may be cut off and you need to wait for the next buffer to process it. You might be interested to take a look at my implementation:

• WebSocket Frame Buffer View
• Socket Event Handling Algorithm

Please note that I am pausing the websocket during processing to prevent asynchronous handlers from executing competitively.

Thanks!