Book Image

Node.js Design Patterns

By : Mario Casciaro
Book Image

Node.js Design Patterns

By: 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 fundamental principles and components that define the platform. It then shows you how to master asynchronous programming and how to design elegant and reusable components using well-known patterns and techniques. The book rounds off by teaching you the various approaches to scale, distribute, and integrate your Node.js application.
Table of Contents (16 chapters)
Node.js Design Patterns
Credits
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Index

Promises


We already mentioned at the beginning of the chapter that CPS is not the only way to write asynchronous code. In fact, the JavaScript ecosystem provides alternatives to the traditional callback pattern. One of these in particular is receiving a lot of momentum, especially now that it is going to be part of the ECMAScript 6 specification (also known as ES6 or Harmony), the upcoming version of the JavaScript language. We are talking, of course, about promises, and in particular about those implementations that follow the Promises/A+ specification (https://promisesaplus.com).

Note

There are other promises implementations that are not compliant to the Promises/A+ specification, and among those, the most popular is the one provided by JQuery. Most of the topics discussed in this section do not apply to those noncompliant implementations.

What is a promise?

In very simple terms, promises are an abstraction that allow an asynchronous function to return an object called a promise, which represents...