simple-router.js

import Rx from 'rx'


// sources$
const request$ = new Rx.Subject()

const http = require('http')
const fs = require('fs')
const hostname = '127.0.0.1'
const port = 1337

http.createServer(
    (req, res) => {
      request$.onNext({
        body: req,
        res
      })
    })
  .listen(port, hostname, () => {
    console.log(`Server running at http://${hostname}:${port}/`)
  });

// helpers
const mapRequest = (f) => (request) => ({
  ...request,
  body: f(request.body),
})

const flatMapRequest = (f) => (request) => {
  return Rx.Observable.of(request.body)
    .flatMap(f)
    .map(
      body => ({
        ...request,
        body,
      })
    )
}

function readFile(fileName) {
  return new Promise((resolve, reject) => {
    fs.readFile(
      './public/' + fileName,
      (error, data) => error ? reject(error) : resolve(data)
    )
  })
}

//main
const response$ = request$
  .map(mapRequest(x => 'index.html'))
  .flatMap(flatMapRequest(readFile)

//sink$
response$.subscribe(
  ({
    body,
    res
  }) => {
    res.end(body)
  }
)