Express.js is a web application framework for Node.js. It is designed for building web applications and APIs. It has been called the de facto standard server framework for Node.js.


You need to have node.js installed

Quick set-up

Run the below command to quickly create an application skeleton

npx express-generator

And then run

npm i

to install all necessary modules

Start the server

add this code in app.js

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.send('Hello World!')

app.listen(port, () => {
  console.log(`Example app listening on port ${port}`)

and run app.js to start the serve. Go to localhost:port to see the response


Route definition

The routing definition syntax is


Here, METHOD is an HTTP request method, and HANDLER is the function executed when the route is matched.

Serve an HTML file

app.get('/', (req, res) => {
      res.sendFile(__dirname +'/views/index.html') ;

Serve Static assets

Static assets include things like css files app.use(‘/public’,express.static(__dirname + ‘/public’));

Serve JSON

Serve a JSON response app.get(‘/json’,myFunction2); function myFunction2(req, res) { res.json({“message”: “Hello json”}) ; }