Expressjs Cheatsheet

December 21, 2022

Setup

mkdir app-name
cd myapp

npm init

entry point: (index.js)

npm install express

npm install express --no-save

In index.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}`)
})

Run app

node app.js

Express application generator

npx express-generator

or 

npm install -g express-generator
express

cd myapp
npm install

Basic routing

app.METHOD(PATH, HANDLER)

The following examples illustrate defining simple routes.

Respond with Hello World! on the homepage:

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

Respond to POST request on the root route (/), the application’s home page:

app.post('/', (req, res) => {
  res.send('Got a POST request')
})

Respond to a PUT request to the /user route:

app.put('/user', (req, res) => {
  res.send('Got a PUT request at /user')
})

Respond to a DELETE request to the /user route:

app.delete('/user', (req, res) => {
  res.send('Got a DELETE request at /user')
})

Serving static files in Express

express.static(root, [options])

app.use(express.static('public'))

// To use multiple static assets directories, call the express.static middleware function multiple times:

app.use(express.static('public'))
app.use(express.static('files'))

app.use('/static', express.static('public'))

const path = require('path')
app.use('/static', express.static(path.join(__dirname, 'public')))

Examples -

express/examples at master · expressjs/express