Node.js is a platform built on Chrome's JavaScript runtime for easily building fast and scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.
What is Node.js?
In simple words Node.js is "Server-side Javascript"
Features
- Asynchronous and Event Driven - means the server never waits for an API to return data. The server moves to the next API after calling it and a notification mechanism of Events of Node.js helps the server to get a response from the previous API call. (non-blocking I/O)
- Very Fast - built on Google Chrome's V8 JavaScript Engine
- Command line tool
- Modular
- Javascript for both client and server side - works well with single page applications (React, Angular or simply jQuery)
- Has a very good package manager (npm)
Node.js - REPL Terminal
REPL stands for Read Eval Print Loop and it represents a computer environment like a window console or Unix/Linux shell where a command is entered and system responds with an output in interactive mode. You can perform the following tasks;
- Read - Reads user's input, parse the input into JavaScript data-structure and stores in memory.
- Eval - Takes and evaluates the data structure
- Print - Prints the result
- Loop - Loops the above command until user press ctrl-c twice.
REPL feature of Node is very useful in experimenting with Node.js codes and to debug JavaScript codes.
Node Package Manager - NPM
Node Package Manager (npm) provides following two main functionalities:
- Online repositories for node.js packages/modules which are searchable on search.nodejs.org
- Command line utility to install Node.js packages, do version management and dependency management of Node.js packages.
Mostly used NPM commands
-
npm install <Module Name>
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npm install binarysearch -g
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npm update binarysearch
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npm uninstall binarysearch
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npm init
package.json
package.json is present in the root directory of any Node application/module and is used to define the properties of a package.
npm comes bundled with Node.js
Installation
A Node.js application consists of following three important parts
- Import required modules − We use require directive to load a Node.js module.
- Create server − A server which will listen to client's request similar to Apache HTTP Server.
- Read request and return response − server created in earlier step will read HTTP request made by client which can be a browser or console and return the response.