Why middleware is fundamental in Node.js - See It in Action

Why middleware is fundamental

📖 Scenario: You are building a simple web server using Node.js and Express. Middleware functions help your server handle requests step-by-step, like a helpful assistant passing tasks along.

🎯 Goal: Create a basic Express server that uses middleware to log requests and send a response. This will show how middleware works in a real server.

📋 What You'll Learn

Create an Express app instance

Add a middleware function that logs the HTTP method and URL of each request

Add a route handler for GET requests to '/' that sends a welcome message

Start the server listening on port 3000

💡 Why This Matters

🌍 Real World

Middleware is used in real web servers to handle tasks like logging, authentication, and error handling step-by-step.

💼 Career

Understanding middleware is essential for backend developers working with Node.js and Express to build scalable and maintainable web applications.

1

Set up Express app

Write import express from 'express' and create a variable called app by calling express().

Node.js

import express from 'express'

// Your code here

Need a hint?

Use import express from 'express' to bring in Express, then const app = express() to create your app.

2

Add logging middleware

Add a middleware function using app.use that takes req, res, and next parameters. Inside it, log the request method and URL using console.log, then call next().

Node.js

import express from 'express'

const app = express()

// Your code here

Need a hint?

Middleware functions get req, res, and next. Log the method and URL, then call next() to continue.

3

Add route handler

Add a GET route handler for path '/' using app.get. The handler should send the text 'Welcome to the middleware demo!' using res.send.

Node.js

import express from 'express'

const app = express()

app.use((req, res, next) => {
  console.log(`${req.method} ${req.url}`)
  next()
})

// Your code here

Need a hint?

Use app.get with path '/' and send the welcome message with res.send.

4

Start the server

Call app.listen with port 3000 and a callback function that logs 'Server running on port 3000'.

Node.js

import express from 'express'

const app = express()

app.use((req, res, next) => {
  console.log(`${req.method} ${req.url}`)
  next()
})

app.get('/', (req, res) => {
  res.send('Welcome to the middleware demo!')
})

// Your code here

Need a hint?

Use app.listen(3000, () => { ... }) to start the server and log a message.