How to Reduce API Calls Using Promises in JavaScript

Discover an effective way to reduce redundant API calls by leveraging promises in JavaScript. Learn how to optimize your code for better performance.
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This video is based on the question https://stackoverflow.com/q/66319356/ asked by the user 'Varun Sukheja' ( https://stackoverflow.com/u/6715606/ ) and on the answer https://stackoverflow.com/a/66319946/ provided by the user 'Jonas Wilms' ( https://stackoverflow.com/u/5260024/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Reduce API Calls Using Promises in JavaScript

In today's fast-paced development environment, optimizing the number of API calls your application makes can significantly improve performance. Redundant API calls not only slow down your application but also may lead to throttling issues. This guide will introduce a solution for reducing such calls by utilizing promises effectively in JavaScript.

The Problem at Hand

Suppose you have a function that makes an API call to retrieve a token based on a provided ID and token. However, when multiple instances of this function run concurrently (for example, when you have 5-10 requests kicking off simultaneously), they each initiate their own individual API requests. This redundancy not only wastes resources but can lead to slower response times:

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

In the above code snippet, if the token is not present in the map, a new API request is sent each time the function is called. If 5-10 of these calls happen simultaneously, multiple identical requests to the token API are made, leading to unnecessary network load.

The Solution: Using Promises to Store Requests

To combat this issue, you can store the promise of the API call in the map object instead of just the result. Here's how it can be done:

Step-by-Step Implementation

Check if the ID exists in the map: Begin by checking if the map[id] is already populated. If it is, simply return the existing promise.

Make the API Call: If the ID does not exist, create a new API request, and store the promise in map[id].

Return the promise: Both the initial caller and subsequent calls will wait for the promise to resolve, thus avoiding redundant network calls.

Refactored Code Example

Here's an improved version of your API call function:

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

Benefits of This Approach

Reduced API Calls: By consolidating multiple requests into a single promise, you effectively reduce the number of calls made to the API server.

Improved Performance: Waiting for one API call to complete helps streamline your application's performance, avoiding unnecessary loading times.

Efficient Resource Usage: Your application makes fewer network requests, conserving bandwidth and server resources.

Conclusion

By utilizing promises effectively, you can drastically reduce the number of API calls in situations where multiple requests for the same data may be initiated. This not only enhances the user experience but also optimizes your application’s performance and resource usage. Implementing the solution above will help ensure that your API calls are made more judiciously, ultimately leading to a smoother and more efficient application.

By following this guide, you can take control of the way your web app interacts with external APIs—making it faster and more reliable in handling user requests.