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Learn how to effectively use `AbortController` to cancel ongoing fetch requests in JavaScript, ensuring better user experience and optimized performance.
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This video is based on the question https://stackoverflow.com/q/73540312/ asked by the user 'deaponn' ( https://stackoverflow.com/u/17663717/ ) and on the answer https://stackoverflow.com/a/73540430/ provided by the user 'T.J. Crowder' ( https://stackoverflow.com/u/157247/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Properly Use AbortController to Manage Fetch Requests in JavaScript

Managing async operations in JavaScript can sometimes feel overwhelming, especially when it involves making network requests that can be aborted. If you're working with dynamic data, such as filters, you might encounter situations where initiating a new request should cancel a previous one. This is where the AbortController comes into play. In this post, we will explore how to effectively manage ongoing fetch requests and avoid premature terminations.

The Problem: Unwanted Request Abortions

Imagine you have a scenario where a user can change filters for product listings. The expectation is that when users change filters, any ongoing requests should be aborted to prevent outdated data from being shown. However, you might find that the request is being aborted immediately, or that there are multiple requests being initiated inadvertently.

Here’s an illustration of the original problem encountered:

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

Key Issue:

The request gets aborted prematurely, even on the first function call.

The Solution: Managing AbortController Efficiently

Proposed Code Adjustment

The solution lies in how you instantiate and manage your AbortController. Here’s an effective way to refactor the code:

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

Breakdown of the Solution

Initialization:

Start with an undefined controller.

Abort Previous Request:

Use optional chaining (controller?.abort()) to safely call abort() if there is an active controller.

New Controller for Current Request:

Immediately create a new AbortController instance each time fetchData() is called.

Fetch with Current Signal:

Always use the newly created controller's signal for the current fetch request.

Check Response Status:

Include a check to handle any errors returned from the fetch operation.

Why the Original Error Occurred

The original implementation made recursive calls to fetchData(filters) without properly ensuring that the request hadn't already been initiated, resulting in multiple requests firing. This led to logging "fetch fulfilled" multiple times. The revised approach ensures that any new fetch call will only execute after any previous requests have been aborted.

Conclusion

Using AbortController effectively can greatly enhance the way you handle network requests in dynamic applications. By ensuring that each request has a dedicated controller and aborting any previous requests, you can optimize data retrieval and improve user experience. As your applications grow, mastering patterns like this will not only streamline your code but also lead to more efficient data handling practices.

By following the steps outlined in this post, you should be well-equipped to manage fetch requests in your projects without unintended consequences. Happy coding!