Understanding How to Properly Use async-await with Fetch in JavaScript

Discover how to execute functions after a fetch request using `async-await` in JavaScript to avoid premature execution.
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Understanding How to Properly Use async-await with Fetch in JavaScript

JavaScript can sometimes be tricky, especially when dealing with asynchronous operations such as fetching data from an API. One common confusion arises when trying to get a function to execute after a fetch operation. In this post, we’ll explore this issue and provide a clear solution to ensure that your functions run in the correct order.

The Problem: Functions Running Out of Order

You may have encountered a scenario where you attempt to call a function that relies on the result of a fetch operation, but it appears to run before the fetch completes. This can lead to unexpected behaviors in your application, resulting in functions executing prematurely.

For instance, consider this code snippet:

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

Root Cause: forEach and Its Behavior

TL;DR:

Instead, you can utilize a for...of loop, which does respect the async-await pattern, making it easier to manage asynchronous tasks one at a time.

Solution: Switching to a for...of Loop

Step-by-Step Breakdown

To ensure your asynchronous functions execute in the correct order, follow these steps:

Change the Loop Type: Switch from forEach to for...of so that each iteration can await the completion of the async tasks.

Await Fetch Responses: Make sure you await not just the fetch call, but also the subsequent processing of the response.

Here’s an updated version of the show_name function that encapsulates these changes:

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

Call the Function Properly: Finally, call the show_name() function and chain it with a .then() to ensure everything works smoothly post-fetch.

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

Summary of Key Changes

Utilized for...of: Ensured that we can await inside the loop.

Awaited Fetch: Made sure we wait for the fetch response before proceeding.

Conclusion

Incorporating proper structure in your asynchronous JavaScript functions is crucial to avoid unexpected results. By switching to a for...of loop and ensuring that you await your fetch calls, you can have complete control over the order of execution. This approach will enhance the reliability of your asynchronous code and improve your overall programming efficiency in JavaScript.

By following these guidelines, you'll prevent functions from running prematurely and ensure that your data is fetched and processed correctly before any subsequent operations.