Writing an Express middleware

var express = require('express')
var app = express()

var myLogger = function (req, res, next) {
  console.log('LOGGED')
  next()
}

app.use(myLogger)

app.get('/', function (req, res) {
  res.send('Hello World!')
})

app.listen(3000

var express = require('express')
var app = express()

var requestTime = function (req, res, next) {
  req.requestTime = Date.now()
  next()
}

app.use(requestTime)

app.get('/', function (req, res) {
  var responseText = 'Hello World!<br>'
  responseText += '<small>Requested at: ' + req.requestTime + '</small>'
  res.send(responseText)
})

app.listen(3000)

var express = require('express')
var cookieParser = require('cookie-parser')
var cookieValidator = require('./cookieValidator')

var app = express()

async function validateCookies (req, res, next) {
  await cookieValidator(req.cookies)
  next()
}

app.use(cookieParser())

app.use(validateCookies)

// error handler
app.use(function (err, req, res, next) {
  res.status(400).send(err.message)
})

app.listen(3000)