Book Image

Designing React Hooks the Right Way

By : Fang Jin
Book Image

Designing React Hooks the Right Way

By: Fang Jin

Overview of this book

React hook creates a unique solution for using states in function components to orchestrate UI communication. They provide you with an easy interface to write custom data management solutions with low development and maintenance costs. Understanding how Hooks are designed enables you to use them more effectively, and this book helps you to do just that. This book starts with a custom-crafted solution to reveal why Hooks are needed in the first place. You will learn about the React engine and discover how each built-in Hook can manage a persistent value by hooking into it. You will walk through the design and implementation of each hook with code so that you gain a solid understanding. Finally, you'll get to grips with each Hook's pitfalls and find out how to effectively overcome them. By the end of this React book, you'll have gained the confidence to build and write Hooks for developing functional and efficient web applications at scale.
Table of Contents (12 chapters)

Reusing a last assignment

Reusing a value and memorizing a value sometimes refer to similar behavior. However, it's worth noting that the useMemo hook can only remember one value from the past, the last value.

A single JavaScript variable, by default, serves a purpose that, unless overwritten by a new assignment, holds the previously assigned value. So, take caution when reading the word "memo" here. If you take the word "memo" as a single value instead of memorizing all values, it could help you visualize it the right way as React designed it. If you are interested in classical memorization, check out the Appendix A – Not a classical memorization section at the end of this chapter.

How useMemo reuses the previous assignment is controlled by a deps dependency array, and it uses the areDepsEqual utility function to compare two dependency arrays between the previous and current update. We have already examined this function in Chapter 5, Use Effect...