Understanding Why await Doesn’t Wait: How to Properly Handle Asynchronous Code in Node.js

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The Problem

You’re trying to acquire a lease on a blob in Azure Blob storage and then download the blob, using the lease ID obtained in the previous step. Your initial approach looked like this:

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

However, your acquireLease function was not behaving as expected. Rather than waiting for the lease acquisition to finish before executing the download, your code was moving too quickly, causing the download to execute prematurely.

Analysis of the Original Code

Let's break down your acquireLease function:

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

The Solution: Using Promises Correctly

You were on the right track with your intention to use Promises. Here’s a refined version of your acquireLease function that correctly implements Promises to handle the asynchronous call:

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Key Changes Explained

Return a Promise: The function now explicitly returns a Promise object. This is crucial because it allows the calling code to wait for the async operation to resolve or reject.

Using resolve and reject:

If error is truthy, we call reject(error), passing the error back to the caller.

Updating the Usage of await

With the updated promise-based function, you can now utilize the await keyword effectively like so:

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

Conclusion