NodeJS script for a simple TCP server

tcp_server.js

var net = require('net');

var PORT = 6969;

net.createServer(function(sock) {
    console.log('CONNECTED: ' + sock.remoteAddress +':'+ sock.remotePort);
    
    sock.on('data', function(data) {
        //console.log('RAW DATA RCVD: ' + sock.remoteAddress + ': ' + data);
        var readData = data + '';
        
        if (readData[readData.length -1] == '\0') { // check if end of msg (if last char is null)
            var msg = readData.split('\0'); // split data at null
            for (var i = 0, len = msg.length; i < len; i++) {
                if (msg[i].length > 0) { // if not dead end, echo msg
                    console.log('MSG RCVD: ' + msg[i]);
                    sock.write(msg[i] + '\0');
                }
            }
        } else {
            readData += readData; // append to new data and wait for null char
        }
    });

    sock.on('close', function(data) {
        console.log('CLOSED: ' + sock.remoteAddress +' '+ sock.remotePort);
    });
    
    sock.on('end', function(data) {
        console.log('CLOSED: ' + sock.remoteAddress +' '+ sock.remotePort);
    });

    sock.on('error', (err) => {
        console.log('TCP error', err)
    })
    
}).listen(PORT);

console.log('Server listening on port ' + PORT);