Websocket Server in Node JS

index.js

'use strict';
const https = require('https');
const fs = require('fs');
const express = require('express');
const path = require('path');
const { createServer } = require('http');
const WebSocket = require('ws');
const app = express();

const port = 2222;

const server = https.createServer({
    // you need to change this, depends on your own SSL environment,
    // see - https://letsencrypt.org/getting-started/ and https://certbot.eff.org/
    // also - https://nginx.org/en/docs/http/configuring_https_servers.html
    // self signed cert for localhost and development
    /*
        openssl req -x509 -out localhost.crt -keyout localhost.key \
  -newkey rsa:2048 -nodes -sha256 \
  -subj '/CN=localhost' -extensions EXT -config <( \
   printf "[dn]\nCN=localhost\n[req]\ndistinguished_name = dn\n[EXT]\nsubjectAltName=DNS:localhost\nkeyUsage=digitalSignature\nextendedKeyUsage=serverAuth")
   
   */
    key: fs.readFileSync('../ssl/localhost.key'),
    cert: fs.readFileSync('../ssl/localhost.crt')
}, app);

function getmem() {
    const used = process.memoryUsage();
    let memstr = ''
    for (let key in used) {
        memstr += `${key} ${Math.round(used[key] / 1024 / 1024 * 100) / 100} MB\n`
    }
    return memstr;
}

function isJsonString(str) {
    try {
        JSON.parse(str);
    } catch (e) {
        return false;
    }
    return true;
}

function sendAllExcept(message, ids) {
    if (undefined === ids) throw new Error('ids must be specified');
    if (!Array.isArray(ids)) ids = [ids];
    for (var i = 0, cLength = CLIENTS.length; i < cLength; i++) {
        if (ids.indexOf(i) !== -1) continue;
        CLIENTS[i].send(message);
    }
}

var CLIENTS = [];
var id;

const wss = new WebSocket.Server({ server });

wss.on('connection', function(ws) {
    id = Math.random();
    console.log('connection is established : ' + id);
    CLIENTS[id] = ws;
    CLIENTS.push(ws);

    id = setInterval(function() {
        ws.send(JSON.stringify({ function: "showStats", args: { str: getmem() } }), function() {});
    }, 2000);

    console.log('started client interval');

    ws.on('close', function() {
        console.log('stopping client interval');
        clearInterval(id);
    });

    ws.on('message', function(message) {

        let messageType = typeof message;
        if (messageType == "object") {
            console.log("really object")
        }

        if (isJsonString(message)) {
            console.log("this is JSON");
            // if JSON, let's parse it
            let obj = JSON.parse(message);
            console.log("function:", obj.function)
            console.log("args:", obj.args)
            if (obj.function == "lightUp")
                for (let e = 0; e < CLIENTS.length; e++) {
                    CLIENTS[e].send(JSON.stringify({ function: "lightUp", args: obj.args }), function() {});
                }
        } else {
            console.log("not a JSON:", String("String: " + message));
        }

    });
});

server.listen(port, function() {
    console.log('Listening on:' + port);
});