Скачать или смотреть Mastering useState in React: How to Change Class Data Effectively

Learn how to manage class instances inside React's `useState`, understanding state immutability and optimal solutions for better performance in your app.
---
This video is based on the question https://stackoverflow.com/q/64685088/ asked by the user 'Thiago Viana' ( https://stackoverflow.com/u/8723205/ ) and on the answer https://stackoverflow.com/a/64685924/ provided by the user 'Alex Wayne' ( https://stackoverflow.com/u/62076/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Change a data of a class passed as parameter inside React Hooks useState()

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Mastering useState in React: How to Change Class Data Effectively

Managing state in React using Hooks like useState can be a challenge, especially when dealing with complex data structures like classes. If you've ever wondered why your changes to class instances in useState aren't reflecting as expected, you're not alone! Let's dive into the problem and explore a suitable solution.

Understanding the Problem

In React, we often need to collect and manipulate state within our components. However, when we pass objects, particularly class instances, to useState, we face a common issue — mutability. The core of the problem lies in how React determines if the state has changed:

React determines state changes by checking if the new state is strictly equal to the old state (using the === operator).

When you modify properties of an existing class instance that is stored in state, React doesn't recognize that as a change. This means your component will not re-render, and the UI won't update.

This creates confusion for developers who expect changes to their state to trigger re-renders, leading to what seems like "stuck" data.

Delving Deeper into State Management with Classes

Using a class for state is not inherently wrong, but you must manage immutability properly. Here’s how you can achieve that:

1. Understanding Immutable State

To ensure that React sees your updated state, class instances need to be immutable. This means that instead of changing an existing instance directly, you should create a new instance whenever you want to change a value. Here’s an example:

[[See Video to Reveal this Text or Code Snippet]]

2. Updating State

Using the method above, you can assign a new instance of your class to the state. Instead of trying to modify your foo instance directly, here’s how you can effectively change its properties:

[[See Video to Reveal this Text or Code Snippet]]

By creating a new instance (updatedFoo and updatedBar), React recognizes that the state has changed and will trigger a re-render.

Why Use Plain Objects Instead

While it's feasible to use classes with immutability in mind, it's often much simpler to work with plain objects. This keeps your code clean and easier to read. Here’s why many prefer plain objects:

Ease of Use: Objects are easier to manage when updating state, especially with the spread operator.

Less Overhead: There is no need to create methods for managing state changes.

Example of Using Plain Objects

Using plain objects with ... (spread operator) can simplify your code:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Navigating state management within React can sometimes feel overwhelming, especially when working with class instances. By understanding the importance of immutability and considering whether to use classes or plain objects, you can enhance your skills as a React developer. Embracing simpler solutions, like using plain objects, often leads to better performance and cleaner code.

Next time you're in a similar situation, remember to create new instances of your classes to maintain the integrity of your state management process. Happy coding!