Create a simple node.js backend framework

app.js

import http from 'http'

function App () {
  this.plugins = []
}

App.prototype.use = function (middleware) {
  this.plugins.push(middleware)
}

App.prototype.handle = function (req, res, callback) {
  let idx = 0

  const next = () => {
    if (idx >= this.plugins.length) {
      return setImmediate(() => callback())
    }

    const layer = this.plugins[idx++]
    setImmediate(() => {
      layer(req, res, next)
    })
  }
  next()
}

App.prototype.listen = function (port) {
  const handler = (req, res) => {
    return this.handle(req, res, () => {})
  }
  return http.createServer(handler).listen({ port })
}

export { App }

logger.js

function Logger (format) {
  this.format = format || ':method ":url"'
}

Logger.prototype.log = function (req, res) {
  const str = this.format
    .replace(':method', req.method)
    .replace(':url', req.url)

  console.log(str)
}

export { Logger }

main.js

import { Router } from './router.js'
import { Logger } from './logger.js'
import { App } from './app.js'

const logger = new Logger()
const router = new Router()
const app = new App()

app.use((req, res, next) => {
  logger.log(req, res)
  next()
})

router.get('/favicon.ico', (req, res) => {
  res.writeHead(200, {'Content-Type': 'image/x-icon'})
  res.end()
})

router.get('/static/index.css', (req, res) => {
  res.writeHead(200, {'Content-Type': 'text/stylesheet'})
  res.end()
})

router.use('GET', '/home', (req, res) => {
  res.writeHead(200, {'Content-Type': 'text/html'})
  res.write('home page')
  res.end()
})

router.use('GET', '/posts', (req, res) => {
  res.writeHead(200, {'Content-Type': 'text/html'})
  res.write('posts page')
  res.end()
})

app.use((req, res, next) => {
  router.route(req, res)
  next()
})

const server = app.listen(3000)

router.js

import http from 'http'

function Router () {
  this.routes = {}

  http.METHODS.forEach((method) => {
    this.routes[method] = {}
  })
}

Router.prototype.use = function (method, url, callback) {
  this.routes[method][url] = callback
}

Router.prototype.get = function (url, callback) {
  this.use('GET', url, callback)
}

Router.prototype.post = function (url, callback) {
  this.use('POST', url, callback)
}

Router.prototype.put = function (url, callback) {
  this.use('PUT', url, callback)
}

Router.prototype.delete = function (url, callback) {
  this.use('DELETE', url, callback)
}

Router.prototype.route = function (req, res) {
  const callback = this.routes[req.method][req.url]
  callback(req, res)
}

export { Router }