Скачать или смотреть Converting Class Components to Functional Components in React: Avoiding undefined props Errors

Learn how to effectively convert React class components to functional components without encountering `undefined props` errors. This guide provides a detailed breakdown of the solution.
---
This video is based on the question https://stackoverflow.com/q/69228057/ asked by the user 'micogg' ( https://stackoverflow.com/u/8431182/ ) and on the answer https://stackoverflow.com/a/69228105/ provided by the user 'silencedogood' ( https://stackoverflow.com/u/9040866/ ) 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: React - undefined props error when rendering functional component

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.
---
Understanding the undefined props Error in React

If you're new to React and recently attempted to convert a working class component into a functional component, you might have encountered a frustrating error: Uncaught TypeError: Cannot read properties of undefined (reading 'props'). This problem typically arises when the props are not being correctly passed or accessed within the functional component. In this guide, we'll tackle this issue head-on and guide you through the solution step-by-step.

The Problem

You had a functional component that was working well in a class format. After switching to a functional version, the rendering broke, and you faced the undefined props error. This often occurs due to two main issues:

Not passing props properly.

Misusing this context in functional components.

Let’s dive into the solution to resolve this issue effectively.

Solution: Correctly Setting Up Your Functional Component

Step 1: Passing Props

In a functional component, you do not need to use this to access the props. Instead, you should pass props directly as a parameter. This allows you to access the props easily without referencing this. Here’s how to do it correctly:

Original Component Snippet:

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

Corrected Code:

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

Step 2: Simplifying the Component Definition

When converting to a functional component, you also want to avoid multiple exports. Simply declare your component and export it in one step. For example:

Before:

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

After:

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

Final Code Example

Combining both steps, your final component should look like this:

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

Conclusion

Switching from class components to functional components in React can be a smooth transition if you properly manage the way you handle props. By following the tips and examples outlined in this guide, you can effectively resolve undefined props errors and enhance your knowledge of React's functional components. Keep practicing, and you'll soon be proficient in navigating the challenges of React development!