NodeJS

Introduction

• Developed by Ryan Dahl.
  
• Created with the aim of creating real-time websites with push capabilities (websockets).
  
• NodeJS is an open source, cross platform runtime environment for server-side and networking applications.
  
• Build on V8 engine, Chrome’s JavaScript engine.
  
• Uses event-driven, non-blocking I/O model which makes NodeJS lightweight and efficient.
  
• Ideal for data-intensive real-time applications that run across distributed devices.
  
• NodeJS comes with several JavaScript libraries that help basic programming.
  
• NodeJS eco-system ‘npm’ is the largest in the world for open source libraries.

● Advantages

• Ability to use single programming language from one end of the application to the other end.
  
• NodeJS applications are easy to scale both horizontally and vertically.
  
• Delivers improved performance since V8 engine compile the JS code into machine code directly.
  
• Performance increased via caching modules into memory after the first use.
  
• Easily extensible.
  
• Support for common tools like unit testing.
  
• Well build ‘npm’ package manager and it’s large number of reusable modules.
  

● Disadvantages

• Even though there are number of libraries available, the actual number of robust libraries is comparatively low.
  
• Not suitable for computationally intensive tasks.
  
• Asynchronous programming model is complex than synchronous model.
  

● Node package manager

• Reusable NodeJS components easily available through online repository.
  
• Build in version and dependency management.
  
• Build in scripting mechanism.
  
• Performance increased via caching modules into memory after the first use.
  
• Global installations will be available throughout the system while local installations will only be available for that particular application.
  
• By default all the dependencies will get installed to ‘node_modules’ directory.
  
• ‘package.json’ contains all information related to the NodeJS application. The file be placed in the root directory of the application.
  
• ‘package.json’ will contain name, version, author, repository, required node version, scripts and dependencies etc.
  

● Node require

• NodeJS follows commonJS pattern when loading modules.
  
• Require modules get loaded synchronously and will be cached after the first use.
  
• If the file does not start with ./, ../, or / module is not a core module NodeJS will look the dependency on the node_modules directory.