Book Image

Node.js Design Patterns - Third Edition

By : Mario Casciaro, Luciano Mammino
5 (1)
Book Image

Node.js Design Patterns - Third Edition

5 (1)
By: Mario Casciaro, Luciano Mammino

Overview of this book

In this book, we will show you how to implement a series of best practices and design patterns to help you create efficient and robust Node.js applications with ease. We kick off by exploring the basics of Node.js, analyzing its asynchronous event driven architecture and its fundamental design patterns. We then show you how to build asynchronous control flow patterns with callbacks, promises and async/await. Next, we dive into Node.js streams, unveiling their power and showing you how to use them at their full capacity. Following streams is an analysis of different creational, structural, and behavioral design patterns that take full advantage of JavaScript and Node.js. Lastly, the book dives into more advanced concepts such as Universal JavaScript, scalability and messaging patterns to help you build enterprise-grade distributed applications. Throughout the book, you’ll see Node.js in action with the help of several real-life examples leveraging technologies such as LevelDB, Redis, RabbitMQ, ZeroMQ, and many others. They will be used to demonstrate a pattern or technique, but they will also give you a great introduction to the Node.js ecosystem and its set of solutions.

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Table of Contents (16 chapters)
Preface
Preface
What you need for this book
Who this book is for
What this book covers
To get the most out of this book
Get in touch
1
The Node.js Platform
The Node.js Platform
The Node.js philosophy
How Node.js works
JavaScript in Node.js
Summary
Free Chapter
2
The Module System
The Module System
The need for modules
Module systems in JavaScript and Node.js
The module system and its patterns
CommonJS modules
Module definition patterns
ESM: ECMAScript modules
ESM and CommonJS differences and interoperability
Summary
3
Callbacks and Events
Callbacks and Events
The Callback pattern
The Observer pattern
Summary
Exercises
4
Asynchronous Control Flow Patterns with Callbacks
Asynchronous Control Flow Patterns with Callbacks
The difficulties of asynchronous programming
Callback best practices and control flow patterns
The async library
Summary
Exercises
5
Asynchronous Control Flow Patterns with Promises and Async/Await
Asynchronous Control Flow Patterns with Promises and Async/Await
Promises
Async/await
The problem with infinite recursive promise resolution chains
Summary
Exercises
6
Coding with Streams
Coding with Streams
Discovering the importance of streams
Getting started with streams
Asynchronous control flow patterns with streams
Piping patterns
Summary
Exercises
7
Creational Design Patterns
Creational Design Patterns
Factory
Builder
Revealing Constructor
Singleton
Wiring modules
Summary
Exercises
8
Structural Design Patterns
Structural Design Patterns
Proxy
Decorator
The line between proxy and decorator
Adapter
Summary
Exercises
9
Behavioral Design Patterns
Behavioral Design Patterns
Strategy
State
Template
Iterator
Middleware
Command
Summary
Exercises
10
Universal JavaScript for Web Applications
Universal JavaScript for Web Applications
Sharing code with the browser
Fundamentals of cross-platform development
A brief introduction to React
Creating a Universal JavaScript app
Summary
Exercises
11
Advanced Recipes
Advanced Recipes
Dealing with asynchronously initialized components
Asynchronous request batching and caching
Canceling asynchronous operations
Running CPU-bound tasks
Summary
Exercises
12
Scalability and Architectural Patterns
Scalability and Architectural Patterns
An introduction to application scaling
Cloning and load balancing
Decomposing complex applications
Summary
Exercises
13
Messaging and Integration Patterns
Messaging and Integration Patterns
Fundamentals of a messaging system
Publish/Subscribe pattern
Task distribution patterns
Request/Reply patterns
Summary
Exercises
14
Other Books You May Enjoy
Other Books You May Enjoy
15
Index
Index

Decorator

Decorator is a structural design pattern that consists in dynamically augmenting the behavior of an existing object. It's different from classical inheritance, because the behavior is not added to all the objects of the same class, but only to the instances that are explicitly decorated.

Implementation-wise, it is very similar to the Proxy pattern, but instead of enhancing or modifying the behavior of the existing interface of an object, it augments it with new functionalities, as described in Figure 8.2:

Figure 8.2: Decorator pattern schematic

In Figure 8.2, the Decorator object is extending the Component object by adding the methodC() operation. The existing methods are usually delegated to the decorated object without further processing but, in some cases, they might also be intercepted and augmented with extra behaviors.

Techniques for implementing decorators

Although proxy and decorator are conceptually two different patterns with different...

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