Node.js Introduction

What is Node.js?

  • Node.js is an open source server environment
  • Node.js is free
  • Node.js runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
  • Node.js uses JavaScript on the server

Why Node.js?

Node.js uses asynchronous programming!

A common task for a web server can be to open a file on the server and return the content to the client.

Here is how PHP or ASP handles a file request:

  1. Sends the task to the computer's file system.
  2. Waits while the file system opens and reads the file.
  3. Returns the content to the client.
  4. Ready to handle the next request.

Here is how Node.js handles a file request:

  1. Sends the task to the computer's file system.
  2. Ready to handle the next request.
  3. When the file system has opened and read the file, the server returns the content to the client.

Node.js eliminates the waiting, and simply continues with the next request.

Node.js runs single-threaded, non-blocking, asynchronous programming, which is very memory efficient.

What Can Node.js Do?

  • Node.js can generate dynamic page content
  • Node.js can create, open, read, write, delete, and close files on the server
  • Node.js can collect form data
  • Node.js can add, delete, modify data in your database

What is a Node.js File?

  • Node.js files contain tasks that will be executed on certain events
  • A typical event is someone trying to access a port on the server
  • Node.js files must be initiated on the server before having any effect
  • Node.js files have extension ".js"

Node.js is an open source server environment.

Node.js allows you to run JavaScript on the server.

Example

var http = require('http');

http.createServer(function (req, res) {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello World!');
}).listen(8080);
console.log('This example is different!');
console.log('The result is displayed in the Command Line Interface');

 

Node.js has a set of built-in modules.

Node.js has a set of built-in modules which you can use without any further installation.

Here is a list of the built-in modules of Node.js version 6.10.3:

Module Description
assert Provides a set of assertion tests
buffer To handle binary data
child_process To run a child process
cluster To split a single Node process into multiple processes
crypto To handle OpenSSL cryptographic functions
dgram Provides implementation of UDP datagram sockets
dns To do DNS lookups and name resolution functions
domain Deprecated. To handle unhandled errors
events To handle events
fs To handle the file system
http To make Node.js act as an HTTP server
https To make Node.js act as an HTTPS server.
net To create servers and clients
os Provides information about the operation system
path To handle file paths
punycode Deprecated. A character encoding scheme
querystring To handle URL query strings
readline To handle readable streams one line at the time
stream To handle streaming data
string_decoder To decode buffer objects into strings
timers To execute a function after a given number of milliseconds
tls To implement TLS and SSL protocols
tty Provides classes used by a text terminal
url To parse URL strings
util To access utility functions
v8 To access information about V8 (the JavaScript engine)
vm To compile JavaScript code in a virtual machine
zlib To compress or decompress files

Download Node.js

Download Node.js from the official Node.js web site: https://nodejs.org