legacy server with logger, body-parser middlewares and connect runner

server.js

const http = require('http')

const logger = (req, res, next) => {
  const time = Date.now()
  res.on('finish', () => {
    const {method, url, headers, body} = req
    const {statusCode} = res
    console.log('%s %s %s %s %j %s', method, url, statusCode, Date.now() - time, headers, JSON.stringify(body))
  })
  next()
}

const bodyParser = (req, res, next) => {
  let body = ''
  req.on('data', c => {
    body += c.toString()
  })
  req.on('end', () => {
    req.body = body
    next()
  })
  req.on('error', (err) => {
    next(err)
  })
}

const connect = (...fns) => (req, res, done) => {
  let i = 0
  function run (err) {
    const fn = fns[i++]
    if (typeof fn === 'function') {
      if (err) {
        if (fn.length === 4) {
          fn(err, req, res, (err) => run(err))
        } else {
          run(err)
        }
      } else {
        if (fn.length === 4) {
          run()
        } else {
          fn(req, res, (err) => run(err))
        }
      }
    } else {
      done && done(err)
    }
  }
  run()
}

http.createServer(
  connect(
    logger,
    bodyParser,
    (req, res) => {
      const {method, url, body} = req
      console.log(method, url, body)
      res.end()
    },
    (err, req, res, next) => {
      console.error(err)
      res.statusCode = 500
      res.end()
    }
  )
).listen(3000)