what is node.js

JavaScript
Javascript was always a client side language until node.js.
Common server side languages include PHP, Python, Perl, Ruby
and several more. Node enables you to use Javascript server side.
This now means you can have a consistent language both ends
which could not be done prior to Node.//Author: Mohammad Arman Khan
//How To Install Node.js on Ubuntu

1: sudo apt-get update
2: sudo apt-get install nodejs
3: sudo apt-get install npm
4: nodejs -vNodeJs is Runtime environment for executing Js code, Outside Of Browser.
it is build upon Chrome v8 engine using c++.

Uses of Node:

-can build back-end services like API which can be used as backend for 
diferent platform Apps(Website, MobileApp, Desktop App).

-is Asynchronous by default means Single thread handle all the request
and response, thereby providing more speed, highly scalable, built time half 
compare to other tech in market, 33% few line of code, 40% fewer files,
can handle 2times more requests/secs, 35% fast response time.
// Hope you like the short Description.npm install http then write a webserver...
const http = require('http');
const PORT = 3000;

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World');
});

server.listen(port, () => {
  console.log(`Server running at PORT:${port}/`);
});Node js allows you to run javascript outside of your browser
ex: you are able to run it on your terminalExpress is a minimal and flexible Node.js web application framework
that provides a robust set of features for web and mobile
applications.

Source

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