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

Asset loading optimization – async, defer, preconnect, preload, and prefetch

When using script to load and execute JavaScript, there are HTML attributes of script we can use to control the loading and execution.

We can rely on the difference between external scripts and inline scripts; we can also use the async, defer, and type="module" attributes.

We’ll start by defining external and inline scripts, then the async and defer attributes. Finally, we’ll look at classic and module scripts via the type="module" attribute.

External scripts use the src attribute to point to a separate JavaScript file; for example, what follows is an external script that will load and evaluate ./script.js when it’s encountered:

<script src="./script.js"></script>

Contrast this with inline scripts, where there is no src attribute; instead, the JavaScript code is in the script tag contents: