Скачать или смотреть Solving the Issue of Canceling Fetch Requests in Custom Hooks with React

Learn how to properly manage fetch calls in custom React hooks using `useRef` to ensure efficient state handling and cancellation.
---
This video is based on the question https://stackoverflow.com/q/75024108/ asked by the user 'Simon B. Nielsen' ( https://stackoverflow.com/u/20940028/ ) and on the answer https://stackoverflow.com/a/75024240/ provided by the user 'Live bug help - www.dialect.so' ( https://stackoverflow.com/u/19461620/ ) 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: Cancel fetch with continue request in a custom hook

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.
---
Solving the Issue of Canceling Fetch Requests in Custom Hooks with React

When building applications in React, managing asynchronous operations such as data fetching is crucial for maintaining a responsive user experience. Often, developers implement custom hooks to abstract data fetching logic. However, a common issue arises when trying to cancel ongoing fetch requests due to component state changes. In this post, we'll explore a real-world scenario of fetching data with a custom hook and how to effectively handle cancellations.

The Problem

Imagine you have created a custom hook to fetch data, which operates correctly under normal conditions. However, you encounter a problem when trying to cancel a fetch request after a state update.

Here’s a simplified snippet of the current implementation:

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

What's Going Wrong?

When you set enabled to false through setEnabled(false), it reflects in the useEffect hook, but this change does not propagate to the fetchData function. As a result, your fetch continues to run even after you expect it to be canceled. This happens because of a concept in React known as stale closures: the function captures the variables in its scope at the time it was called, meaning it doesn't see later updates to those variables.

The Solution

To solve the issue of stale closures and properly manage fetch cancellations, we can utilize the useRef hook. This hook allows us to keep a mutable reference that persists for the full lifetime of the component, instead of the function closure that is recreated on every render.

Revised Implementation

Here's how you can modify your hook to use useRef for handling the cancellation of fetch requests:

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

Breakdown of Changes

useRef Hook: We introduced isCancelled using the useRef hook, which allows us to maintain a reference that doesn't change across re-renders.

Cancellation Logic: Within the fetchData function, we check !isCancelled.current instead of relying on the enabled state. This ensures that we can break the fetching loop if the component is unmounted or if the user decides to stop fetching.

Update isCancelled State: The useEffect hook updates isCancelled.current based on the enabled state. This way, once setEnabled(false) is called, the next time fetchData checks the condition, it will find isCancelled.current set to true, thus stopping further fetch requests.

Conclusion

By understanding the implications of stale closures in asynchronous operations and effectively using the useRef hook, you can manage fetch requests in React custom hooks more reliably. This adjustment helps you avoid ongoing network requests that could lead to performance issues and unexpected behaviors in your application.

Implementing these changes not only improves your hook’s functionality but also enhances the overall user experience by providing a responsive and efficient data loading mechanism. Happy coding!