app.on express code example

Example 1: express.js server

/* ====== create node.js server with express.js framework ====== */
// dependencies
const express = require("express");

const app = express();

app.get("/", (req, res) => {
   res.send("This is home page.");
});

app.post("/", (req, res) => {
   res.send("This is home page with post request.");
});

// PORT
const PORT = 3000;

app.listen(PORT, () => {
   console.log(`Server is running on PORT: ${PORT}`);
});


// ======== Instructions ========
// save this as index.js
// you have to download and install node.js on your machine
// open terminal or command prompt
// type node index.js
// find your server at http://localhost:3000

Example 2: express hello world

//to run : node filename.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 at http://localhost:${port}`))

//visit localhost:3000
// assuming you have done 1) npm init 2) npm install express

Example 3: express redirect

res.redirect('/foo/bar')
res.redirect('http://example.com')
res.redirect(301, 'http://example.com')
res.redirect('../login')

Example 4: express render

// send the rendered view to the client
res.render('index')

// if a callback is specified, the rendered HTML string has to be sent explicitly
res.render('index', function (err, html) {
  res.send(html)
})

// pass a local variable to the view
res.render('user', { name: 'Tobi' }, function (err, html) {
  // ...
})