var app = require("express")();

​

//This is the middleware function which will be called before any routes get hit which are defined after this point, i.e. in your index.js

app.use(function (req, res, next) {

​

  var authorised = false;

  //Here you would check for the user being authenticated

​

  //Unsure how you're actually checking this, so some psuedo code below

  if (authorised) {

    //Stop the user progressing any further

    return res.status(403).send("Unauthorised!");

  }

  else {

    //Carry on with the request chain

    next();

  }

});

​

//Define/include your controllers

​

router.get('/route', middleware1, middleware2, ..., middlewareX)

​

1)Express app receives a request when someone hits a server for which it will create

request and response.

2)middleware is used to manipulate request.

3)It is middleware because it is a function that run between request and response cycle.

4) middleware stack. middleware that appear first will run first.

5)middleware is like pipeline which end with response object.

//Creating own middleware

//this middleware apply to each and every request

//so,  if we put in last then it will not work.

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

     console.log('Hello from middleware')

     next() 

})

//adding request time 

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

     req.requestTime= new Date().toISOString() //this is method and we need to call that

     next()

})

​

​

app.use('/user/:id', (req, res, next) => {

  console.log('Request Type:', req.method)

  next()

})