If you write server-side JavaScript, chances are you’ve need to read information from environment variables. It’s considered a best practice to share sensitive information, such as access tokens, inside of environment variables to keep them secure. However, the way environment variables are read from JavaScript is error-prone in subtle ways that might take you hours... […]

When promises were introduced in ECMAScript 2015, they had an interesting flaw: if a promise didn’t have a rejection handler and was later rejected, you would have no idea. The rejection silently occurred behind the scenes and, therefore, could easily be missed. The best practice of always attaching rejection handlers to promises emerged due to... […]

In my last post, I walked you through the creation of the Promice.race() and Promise.any() methods, both of which work on multiple promises and return a single promise that indicates the result of the operation. This post continues on to discuss Promise.all() and Promise.allSettled(), two operations that are similar to one another as well as... […]

In the previous posts in this series, I discussed implementing a promise from scratch in JavaScript. Now that there’s a full promise implementation, it’s time to look at how you can monitor multiple promises at once using Promise.race() and Promise.any() (Promise.all() and Promise.allSettled() will be covered in the next post). You’ll see that, for the... […]

When you create a promise with the Promise constructor, you’re creating an unsettled promise, meaning the promise state is pending until either the resolve or reject function is called inside the constructor. You can also created promises by using the Promise.resolve() and Promise.reject() methods, in which case, the promises might already be fulfilled or rejected... […]

In my first post of this series, I explained how the Promise constructor works by recreating it as the Pledge constructor. In the second post in this series, I explained how asynchronous operations work in promises through jobs. If you haven’t already read those two posts, I’d suggest doing so before continuing on with this... […]

In my first post of this series, I explained how the Promise constructor works by recreating it as the Pledge constructor. I noted in that post that there is nothing asynchronous about the constructor, and that all of the asynchronous operations happen later. In this post, I’ll cover how to resolve one promise to another... […]

Early on in my career, I learned a lot by trying to recreate functionality I saw on websites. I found it helpful to investigate why something worked the way that it worked, and that lesson has stuck with me for decades. The best way to know if you really understand something is to take it... […]

GitHub Actions1 are programs designed to run inside of workflows2, triggered by specific events inside a GitHub repository. To date, people use GitHub Actions to do things like run continuous integration (CI) tests, publish releases, respond to issues, and more. Because the workflows are executed inside a fresh virtual machine that is deleted after the... […]