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

The observer pattern in JavaScript

The observer pattern allows an object (the observable or subject) to maintain a list of other objects that depend on it (observers). When a state update occurs in the subject, such as an entity object being created or updated, it notifies the observers.


A sample use case for the observer pattern is an in-memory queue. The Queue instance will have the subscribe, unsubscribe, and notify methods.

subscribe will add an additional “handler” function, unsubscribe will remove a particular “handler” function if it has been registered, and finally, notify will call each handler with a “message” payload. This is the “notification of the observers” piece, where the observable or subject ensures that each registered observer is notified.

subscribe and unsubscribe turn “observer” functionality on and off, respectively. subscribe has to be used to become an “...