JAVASCRIPT

Express Middleware Type

An Express application can use the following types of middleware:

Application-level middleware
Router-level middleware
Error-handling middleware
Built-in middleware
Third-party middleware

middleware in express

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()
})

middleware in express

app.use('/user/:id', (req, res, next) => {
  console.log('Request Type:', req.method)
  next()
})

Express Middleware

const express = require('express');
const app = express();

function middlewareFunction(request, response, next){
  ...
  next()
}

app.use(middlewareFunction)