express app.listen code example

Example 1: app.listen express

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}`)
})

Example 2: 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 3: 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 4: sample express app

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}`))

Example 5: require express server.js

const express = require('express')const app = express() app.get('/', function (req, res) {  res.send('Hello World')}) app.listen(3000)

Example 6: http header express

app.get('/', (req, res) => {
  req.header('User-Agent')
})
// Use the Request.header() method to access
//one individual request header’s value