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Blog postOpen source sustainability is a topic that is just starting to get the attention that it deserves. So much of the technology sector is run on software that can be used for free without any further obligation. However, as companies profit from using this software for free, the maintainers of the software often struggle to find enough time to work on the software while making enough money to survive. Many are forced to work full-time jobs to subsidize the development of these open source projec
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Blog postTraditionally, developers have created properties inside of JavaScript classes for any data that might be needed within an instance. This isn’t a problem for small pieces of data that are readily available inside of the constructor. However, if some data needs to be calculated before becoming available in the instance, you may not want to pay that cost upfront. For example, consider this class:
class MyClass { constructor() { this.data = someExpensiveComputation(); } } Here, t
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Blog postIf you’ve spent any time developing software professionally and then you are probably used to the spirited debates that take place between software engineers as well as between software engineers and management, design, and product. Software engineers are not known for being shy about their opinions on any particular subject, and especially when it comes to the company they work for or the software they work on. However, many software engineers are not good at convincing others of their posit
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Blog postIf 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 to figure out. When an error occurs reading an environment variable, you want to know immediately, and you don’t want to interpr
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Blog postWhen 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 this limitation. Eventually, a way to detect unhandled promise rejections was added to ECMA-262 and both Node.js and web browsers implemented console
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Blog postIn 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 Promise.any(). Each of these methods use the same basic algorithm so if you’re able to understand one of them then you can understand them all.
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Blog postIn 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 most part, all of the methods that work with multiple promises follow a similar algorithm, which makes it fairly easy to move from implementin
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Blog postWhen 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 as soon as they are created. These methods are helpful for wrapping known values in promises without going through the trouble of
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Blog postIn 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 one.
This post focuses on implementing then(), catch(), and finally() according to ECMA-262. This functionality is surprisingly involved and relies on a lot of hel -
Blog postIn 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 promise, which will trigger asynchronous operations.
As a reminder, this series is based on my promise library, Pledge. You can view and download all of the source co
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