How to Properly Chain Async Functions in Node.js for Image Processing

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The Problem

Here’s a snippet of how your code looks initially:

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

In this code, you have a problem: the remove function gets executed before the convert function has finished processing the image. This results in errors because the image is deleted before the conversion is completed.

The Solution: Chaining Async Functions

To effectively chain async functions so that one completes before the next begins, you need to return promises appropriately. Let’s break down how to do this step-by-step.

Step 1: Understanding Promises

The convert function is asynchronous and returns a promise. You need to ensure that the promise resolves before calling the remove function. Here’s how to modify your code:

Step 2: Use .then()

Replace this part of your code:

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

With this:

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

Step 3: Confirm That All Worker Methods are Promises

Ensure that all methods invoked within the convert function return a promise. The modified convert function should look something like this:

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

Step 4: Handle Potential Errors in the Remove Function

It’s always a good idea to handle potential errors gracefully. Update your remove function to ensure it deals with errors correctly:

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

Final Code Structure

After implementing these changes, your complete endpoint should look like this:

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

Conclusion

By appropriately chaining your async functions using .then(), or await, you can ensure that each asynchronous operation completes before starting the next. This method not only prevents errors but also makes your code cleaner and more readable. Next time you find yourself working with multiple asynchronous tasks, remember to enforce the order of execution using promises effectively.