Book Image

Node.js Design Patterns - Second Edition

By : Joel Purra, Luciano Mammino, Mario Casciaro
Book Image

Node.js Design Patterns - Second Edition

By: Joel Purra, Luciano Mammino, Mario Casciaro

Overview of this book

Node.js is a massively popular software platform that lets you use JavaScript to easily create scalable server-side applications. It allows you to create efficient code, enabling a more sustainable way of writing software made of only one language across the full stack, along with extreme levels of reusability, pragmatism, simplicity, and collaboration. Node.js is revolutionizing the web and the way people and companies create their software. In this book, we will take you on a journey across various ideas and components, and the challenges you would commonly encounter while designing and developing software using the Node.js platform. You will also discover the "Node.js way" of dealing with design and coding decisions. The book kicks off by exploring the basics of Node.js describing it's asynchronous single-threaded architecture and the main design patterns. It then shows you how to master the asynchronous control flow patterns,and the stream component and it culminates into a detailed list of Node.js implementations of the most common design patterns as well as some specific design patterns that are exclusive to the Node.js world.Lastly, it dives into more advanced concepts such as Universal Javascript, and scalability' and it's meant to conclude the journey by giving the reader all the necessary concepts to be able to build an enterprise grade application using Node.js.
Table of Contents (20 chapters)
Node.js Design Patterns - Second Edition
Credits
About the Authors
Acknowledgments
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface

Command


Another design pattern with huge importance in Node.js is Command. In its most generic definition, we can consider a Command as any object that encapsulates all the information necessary to perform an action at a later time. So, instead of invoking a method or a function directly, we create an object representing the intention to perform such an invocation; it will then be the responsibility of another component to materialize the intent, transforming it into an actual action. Traditionally, this pattern is built around four major components, as shown in the following figure:

The typical organization of the Command pattern can be described as follows:

  • Command: This is the object encapsulating the information necessary to invoke a method or function.

  • Client: This creates the command and provides it to the Invoker.

  • Invoker: This is responsible for executing the command on the target.

  • Target (or Receiver): This is the subject of the invocation. It can be a lone function or the method...