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Learn the best practices for returning values from asynchronous functions in Node.js. Discover how to streamline your Express server logic for better performance and reliability.
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How to Properly Return Values from Async Functions in Node.js and Express

In the world of web development, managing asynchronous operations can often be challenging, especially when dealing with multiple scripts and functions. If you find yourself struggling to return values from a mix of async and synchronous functions, you're not alone. This guide will address common pitfalls and offer a clear solution to streamline your Node.js and Express application.

The Problem: Confusion between Async and Sync Code

In a typical Node.js application that uses Express to handle HTTP requests, you may have a setup where one script acts as your main server, while another script serves as a provider that manages background tasks—like interacting with a blockchain.

The challenge arises when you need to return values from the provider back to the Express server, especially if you use both async/await syntax and promises (via .then()), leading to confusion or undefined values.

Key Issues Explained:

Mixing Syntax: Combining await with .then() can lead to unexpected behavior and makes your code harder to read.

Undefined Responses: If asynchronous tasks aren’t properly awaited, you might end up with undefined values being sent back in your HTTP responses.

The Solution: Streamline Your Async Logic

To resolve these issues, let's focus on how to structure your code correctly, ensuring your async functions behave as expected. Here's a revised approach you can adopt:

Step 1: Modify Your Provider Function

Instead of mixing await and .then(), you should use await to handle the asynchronous operation cleanly. Here’s how to adjust your provider script:

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

Step 2: Simplify the Server Script

Next, structure your server request handler to await the result properly and handle potential errors:

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

Why Does This Work?

Clear Control Flow: By using await, you ensure that the response from getInfo is resolved before proceeding, which eliminates the chance of undefined values.

Error Handling: The try/catch structure ensures that any errors can be caught and handled in one place, making your code easier to manage.

Ease of Reading: Removing .then() makes it simpler to read and understand how your asynchronous workflow operates.

Conclusion

When working with asynchronous functions in Node.js and Express, it’s crucial to maintain a clear structure. Avoid mixing await with .then() to ensure your values get passed correctly without confusion. By following the steps outlined above, you'll enhance the reliability of your application and improve its performance.

With this approach, you’ll find it much easier to maintain your code base and help prevent common asynchronous pitfalls that can arise in complex applications. Happy coding!