Refactoring an Async Function: The Promise Dilemma in JavaScript

Learn how to refactor an async function in JavaScript correctly by understanding when and why to use Promises. This comprehensive guide simplifies the process for developers of all levels.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to refactor an async function with Promise inside of it

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Refactoring an Async Function: The Promise Dilemma in JavaScript

In the world of JavaScript, async functions are a powerful tool to handle asynchronous operations more elegantly than traditional callbacks or Promises. However, developers often find themselves questioning the need for nested Promises within these functions. In this guide, we will dive into a common scenario that many JavaScript developers encounter: how to refactor an async function that invokes a Promise. We'll explore whether it is necessary to use new Promise in an async function and how to resolve common pitfalls with practical examples.

The Problem

Consider the following async function that returns a Promise:

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

In this example, the function doSomething(userId) unnecessarily wraps its logic inside new Promise(...). If we simply remove it, the return statement changes, but the function fails to work as expected, returning undefined due to the missing return value. This leads to errors when the function is called elsewhere, such as:

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

The Solution

To effectively refactor the function, we need to follow these steps:

1. Remove the Nested Promise

Firstly, it is essential to understand that you don’t need to explicitly return a Promise in an async function, as it automatically wraps the return value in a Promise. Therefore, we can simply refactor the function as follows:

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

2. Handle Errors Gracefully

Instead of throwing errors within the function, it's advisable to handle them gracefully to avoid unexpected termination. You can use try...catch blocks to capture errors instead of throwing them. Here's how:

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

3. Call the Function Correctly

When calling doSomething(userId), remember to properly handle the result and any potential errors, like this:

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

Conclusion

Refactoring async functions can significantly improve code readability and maintainability. By eliminating unnecessary Promises and gracefully handling errors, you enhance the quality of your code while simplifying its flow. Remember, the key is to leverage the power of async/await without complicating the structure with unwanted Promise wrappers. Happy coding!