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

Decorator in JavaScript

The decorator pattern is similar to the proxy pattern in that it’s about “wrapping” an object. However, the decorator pattern is about adding functionality to an object at runtime. Different decorators can be applied to an object to add different functionalities to it.


Given the following HttpClient class based on the fetch API, we want to instrument the requests made through this client. HttpClient implements getJson and returns JSON output if the fetch request succeeds:

class HttpClient {
  async getJson(url) {
    const response = await fetch(url);
    if (response.ok) {
      return response.json();
    throw new Error(`Error loading ${url}`);

InstrumentedHttpClient, which is a decorator, might look like the following, where we expose the same getJson method but have the...