express (Javascript Library) Cheatsheet

Express is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.

Installation

npm install express

Hello World server

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

app.set('port', (process.env.PORT || config.port));

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

app.listen(app.get('port'), () => console.log(`Server started on ${app.get('port')} port`))

Basic routing

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

//POST 
app.post('/', function (req, res) {
  res.send('POST request. body:', req.body)
})

//DELETE
app.delete('/:id', function (req, res) {
  res.send('DELETE request for id:'. req.params.id)
})

Static files serving

app.use(express.static(__dirname + '/public'));

logging all routes

app._router.stack.forEach(function(r) {
    if (r.route && r.route.path) {
      console.log(r.route.path)
    }
  });

defining routes in a different file

/routes/users.js file

// File Path: /routes/users.js

var express = require('express');
var router = express.Router();

router.get('/', (req, res) => {
    const users = []; // get from db
    res.send(users);
});

router.get('/:id', (req, res)=> {
    const user = {}; // get from db
    res.send(user);
});

router.post('/', (req, res) => {
    const user = req.body; // save user to db
    res.send({status: 'success'});
});

module.exports = router;

adding routes from /routes/users.js

app.use('/user', require('./routes/user'));

Redirects

router.get('/old-path', function(req, res) {
  res.redirect('/temp-new-path'); // sends a 302
});

router.get('/old-path', function(req, res) {
  res.redirect(301, '/permanent-new-path'); // sends a 301
});