npm install --save express mongoose ejs dotenv

$ npm install --save express

$ npm install express

// npm install express

const express = require('express');

const app = express();

​

app.get('/', (req, res)=> {

  res.send('Hello World');

}) 

​

app.listen(3000,()=>{

 console.log("starting...");

});

 npm install express

const express = require('express');

const app = express();

​

app.get('/', (req, res)=> {

  res.send('Hello World');

}) 

​

app.listen(3000,()=>{

 console.log("starting...");

});

For npm users:

npm i express

​

For yarn users:

yarn add express 

npm install express@4

const express = require('express')

const app = express()

​

app.get('/', function (req, res) {

  res.send('Hello World')

})

​

app.listen(3000)