Book Image

JavaScript Design Patterns

By : Hugo Di Francesco
Book Image

JavaScript Design Patterns

By: Hugo Di Francesco

Overview of this book

Unlock the potential of JavaScript design patterns, the foundation for development teams seeking structured and reusable solutions to common software development challenges in this guide to improving code maintainability, scalability, and performance. Discover how these patterns equip businesses with cleaner and more maintainable code, promote team collaboration, reduce errors, and save time and costs. This book provides a comprehensive view of design patterns in modern (ES6+) JavaScript with real-world examples of their deployment in professional settings. You’ll start by learning how to use creational, structural, and behavioral design patterns in idiomatic JavaScript, and then shift focus to the architecture and UI patterns. Here, you’ll learn how to apply patterns for libraries such as React and extend them further to general web frontend and micro frontend approaches. The last section of the book introduces and illustrates sets of performance and security patterns, including messaging and events, asset and JavaScript loading strategies, and asynchronous programming performance patterns. Throughout the book, examples featuring React and Next.js, in addition to JavaScript and Web API examples, will help you choose and implement proven design patterns across diverse web ecosystems, transforming the way you approach development.
Table of Contents (16 chapters)
Part 1:Design Patterns
Part 2:Architecture and UI Patterns
Part 3:Performance and Security Patterns

Flyweight in JavaScript

The flyweight pattern is where the subset of object properties that have the same value are stored in shared “flyweight” objects.

The flyweight pattern is useful when generating large quantities of objects that share a subset of the same values.


One concept from domain-driven design by Eric Evans is “value objects”. These value objects have the property that their contents matter more than their identity. Let’s take the example of a value object being a “coin” where, for the purposes of payment, two 50-cent coins are interchangeable.

Value objects are interchangeable and immutable (a 50-cent coin can’t become a 10-cent coin). These types of objects are therefore a great fit for the Flyweight pattern.

Not all properties of a “coin” are “value”-driven, for example, certain coins are made from certain materials and coins tend to be issued in a certain...