Resolving Undefined in React Native API Requests with async/await

Learn how to effectively loop through an array in React Native and make API requests using `async/await` without encountering `undefined` responses.
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Resolving Undefined in React Native API Requests with async/await

When working with React Native, you may find yourself needing to loop through an array and make API calls for each item. However, users sometimes encounter issues when integrating async/await with array methods like map. A common scenario is logging undefined responses to the console, even when the API requests seem configured correctly. In this guide, we’ll break down the problem and provide a clear solution.

Understanding the Problem

In the example provided below, the user is attempting to retrieve movie images based on a list of liked movies stored in the application state. The core challenge arises when calling the getMovieImages function inside the asynchronous map function. Here's a simplified version of the code they shared:

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

What’s Going Wrong?

Returning Promises: The map function does not wait for the API calls to resolve. Each iteration creates a promise, but since map returns an array of promises, these promises aren’t handled collectively.

Console Logs Undefined: As a result, the data variable may resolve to undefined for each console log action since the promises are not resolved when logging occurs.

Step-by-Step Implementation

Return the Results: This method will return an array filled with the results once all the API calls are finished, rather than dealing with individual undefined values.

Here’s the updated code snippet:

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

Efficiency: It handles multiple requests in parallel, improving performance compared to awaiting each one individually in a loop.

Conclusion

Feel free to leave your thoughts or questions in the comments below. Happy coding!