The simplest Node.js server

nakadashi.js

const http = require('http');

let appOptions = {
    'localHostUrl': 'http://localhost:'
    //errorHandler
}

let routes = {}

const app = {

    route: function(route, action) {
        if (!routes[route]) {
            if (!route.startsWith('/')) {
                route = "/" + route
            }

            routes[route] = {route: route, action: action}
        }
    },

    option: function(optionName, optionValue) {
        appOptions[optionName] = optionValue
    },
    
    serve: function(port) {
        http.createServer(function (req, res) {
            const route = routeParser(req.url)
            if (routes[req.url]) {
                route.action(req, res)
            } else {
                if (routes['/404']) {
                    routeParser('/404').action(req, res)
                } else {
                    errorHandler(req, res)
                }
            }
        }).listen(port)
        console.log(`Website listening on port ${port} (${appOptions.localHostUrl + port})`);
    }
}

function routeParser(route) {
    return routes[route]
}

function errorHandler(req, res) {
    if (appOptions['errorHandler']) {
        appOptions['errorHandler'](req, res)
    } else {
        res.writeHead(502, { 'Content-Type': 'html' });
        res.write('An error has occured.')
        res.end()
    }
}

exports.app = app;

const {app} = require('./nakadashi.js')

app.route('/', (req, res) => {
    const random = Math.floor(Math.random() * 10)
    res.writeHead(200, { 'Content-Type': 'text' })
    res.write(`Hi! Your server is set up correctly. Here's a random number for you: ${random}`)
    res.end()
})

app.route('404', (req, res) => {
    res.writeHead(200, { 'Content-Type': 'text' })
    res.write('Page not found.')
    res.end()
})

app.serve(3000)

Nakadashi Hello World