How to Properly Load Async Functions in React Native for User Login

Learn how to ensure all async functions complete before dispatching a sign-in action in your React Native app. Follow our step-by-step guide and improve your coding skills!
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How to Properly Load Async Functions in React Native for User Login

When building an application, especially in a framework like React Native, the challenges of handling asynchronous operations can be daunting, particularly when it comes to user authentication. One common issue developers face is ensuring that multiple async functions have completed before executing a subsequent action, such as navigating to a new screen. This is particularly important for actions like logging in a user, where user session details must be accurately retrieved and stored before allowing the user into the app.

In this guide, we will explore a real-world issue faced by a developer during user login handling in React Native and provide a well-structured solution.

The Problem

The core of the issue arises when multiple asynchronous operations—like API calls for logging in and retrieving user-specific data—must be completed before an application dispatches a "SIGN_IN" action or transitions to the next screen. The developer's initial code structure quickly leads to a race condition where the app may attempt to navigate away before all the required data is available, ultimately leading to a poor user experience.

Here's what the developer's initial code looked like:

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

The goal here is clear: the developer needs to ensure that all asynchronous operations complete successfully before dispatching "SIGN_IN." But how can we achieve that?

The Solution

To solve this issue, we can utilize JavaScript's async/await syntax, which allows us to write asynchronous code that is more readable and easier to follow. By refactoring the existing code, we can ensure that each asynchronous function completes before moving to the next instruction. Here’s how to restructure the code:

Step-by-step Refactoring

Change the .then() block to async/await: Instead of chaining promises, we'll use the await keyword to pause the execution until each async function returns.

Handle errors: The try...catch construct will allow us to handle and log any errors that may occur during asynchronous operations.

Here’s the updated code snippet:

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

Key Changes Explained

Await Operator: The use of the await operator in front of async function calls like saveUserInfo and getAppScreensFromAPI ensures that these operations fully complete before moving on to the dispatch call.

Error Handling: Utilizing a try...catch block allows us to gracefully handle errors, logging them appropriately without breaking the entire application flow.

Conclusion

By properly structuring our async calls in React Native, we can ensure that all required operations for user authentication are completed successfully before allowing the user to proceed. This enhances both the reliability of the app and the user experience. Asynchronous programming may seem challenging, but with structured practices like async/await, managing multiple async functions becomes a lot simpler.

So the next time you're working on user authentication or any other feature that relies on multiple async operations, remember to take full advantage of JavaScript's async/await syntax to keep your code clean and efficient.