how to run node application code example

Example 1: node run command

// Run a command asynchronously
const { spawn } = require('child_process');
const dir = spawn('cmd', ['/c', 'dir']);

dir.stdout.on('data', data => console.log(`Stdout: ${data}`));
dir.stderr.on('data', data => console.log(`Stderr: ${data}`));
dir.on('close', code => console.log(`Exit code: ${code}`));

// Run a command synchronously
const { spawnSync } = require( 'child_process' );
const dir = spawnSync('cmd', ['/c', 'dir']);

console.log(`Stdout: ${dir.stdout.toString()}`);
console.log(`Stderr: ${dir.stderr.toString()}`);

Example 2: create node project

#1. server.js
var express = require('express');
var app = express();

app.get('/', function (req, res) {
  res.status(200).send('Hello World!');
});

var port = process.env.PORT || 3000;

var server = app.listen(port, function() {
  console.log('Express server listening on port ' + port);
});

open cmd run server.js
"node server.js"
log:Express server listening on port 3000

& then

open link "http://localhost:3000/" in your browser and show result.

Example 3: srart server js

require('dotenv').config();

const express = require('express');
const server = express();
const cors = require('cors');
const ejs = require('ejs');
const methodOverride = require('method-override');
const pg = require('pg');
const agent = require('superagent');

const client = new pg.Client(process.env.DATABASE_URL);

server.use(methodOverride('_method'));
server.use(express.static('./public'));
server.use(cors());
server.use(express.urlencoded({extended :true}));
server.set('view engine','ejs');

Example 4: run node app locally

// Run this command in your terminal to start your node application.
// Replace the tag with your applications main file name (ex index.js, main.js etc). 
// Add alternative a relative or absolute path before the name.

node <filename>.js

Example 5: javascript running at node

const inNode = new Function('try{return this===global;}catch(err){return false;}')();