Скачать или смотреть How to Resolve the First Element in an Array of Promises in JavaScript

Discover a scalable method to resolve the first fulfilled promise from an array of promises in JavaScript, avoiding unhandled rejections and improving API request efficiency.
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How to Resolve the First Element in an Array of Promises in JavaScript

When working with multiple asynchronous operations, such as requests to different APIs, it's common to want the first fulfilled promise, especially if one request is likely to provide the most accurate result. However, handling multiple promises can get tricky when it comes to speed and error management. In this post, we'll explore a more efficient and scalable way to resolve the first successful promise while avoiding potential pitfalls like unhandled rejections.

The Problem: Handling Multiple Promises

In many scenarios, you may have to perform multiple API requests simultaneously. Each request can take varying amounts of time to fulfill, and if one fails, you want to move on to the next until you find a successful response. The initial code shared in the problem is functional but has significant drawbacks:

Scalability Issues: The approach used in the provided code is not easily scalable for a varying number of promises.

Unhandled Rejections: If a promise fails and you aren't managing rejections correctly, it can lead to uncaught exceptions, crashing your application.

A Better Solution

To improve upon the initial implementation, we can simplify the process using the catch method of promises. This allows us to chain our promises more effectively and add scalability without sacrificing clarity.

Revised Code Example

Here's a streamlined version of the function that resolves the first fulfilled promise from an array:

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

Explanation of the Code

We define an array promises containing our delayed promises.

Each promise is attempted sequentially:

If the first promise (promises[0]) succeeds, it returns the result.

If it fails, we catch the error and move on to the second promise (promises[1]).

If that one fails as well, we catch the error from it and attempt the third (promises[2]).

This approach effectively ensures that as soon as one promise is fulfilled, the entire chain stops, resulting in a quick return of the successful value.

Making it Scalable

If you want to improve scalability and handle any number of promises, you can utilize the reduce method:

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

Avoiding Unhandled Rejections

To prevent rejections from going unhandled, you may also want to modify the reduce function as follows:

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

Conclusion

With this refactored approach, you can simplify the handling of multiple promises in JavaScript while effectively capturing the first successful response. This enhances both performance and reliability, helping prevent common pitfalls associated with unhandled promise rejections.

If you're working with promises frequently, it's essential to adopt strategies that foster clarity and scalability for larger projects. Feel free to adapt the examples above to suit your specific use case!