server.js

// import -> require
const http = require('http');
const debug = require("debug")("node-angular");
const app = require('./backend/app');
// const { debug } = require('console');

const normalizePort = val=>{
    let port = parseInt(val,10);

    if(isNaN(port)){
        return val;
    }

    if(port => 0){
        return port;
    }
    return false;
};

const onError = error=>{
    if(error.syscall != "listen"){
        throw error;
    }

    const bind = typeof addr === "string" ? "pipe " + addr : "port" + port;
    
    switch(error.code){
        case "EACCESS":
            console.error(bind + " requires elevated privileges");
            process.exit(1);
            break;
        case "EADDRINUSE":
            console.error(bind + " is already in use!");
            process.exit(1);
            break;
        
        default:
            throw error;
    }
};

const onListening = ()=>{
    const addr = server.address();
    const bind = typeof addr === "string" ? "pipe" + addr : "port " + port;
    debug("Listen on " + bind);
};


const port = normalizePort(process.env.PORT || "3000");
app.set('port', port);

const server = http.createServer(app);
server.on("error", onError);
server.on("listening", onListening);
server.listen(port);