Originally published November 2018. Updated November 2022.

Modern JavaScript is amazing. There are so many features you might not have had a chance to use, and some that are probably being utilized by some of your favorite frameworks and tooling.

In the beginning was HTML, and our pages were fast. But they were boring, so we added JavaScript.  JavaScript ended up being so capable that we ended up creating entire applications with it, dynamically creating and destroying DOM interactively to users’ delight.

Feature toggles (sometimes referred to as feature flags) are an engineering practice aiming to control application behavior without the need to deploy a code change. The behaviors that toggles can affect range from hiding under development features, limited feature release (canary) to a subset of users, or used to switch to fallback implementation in the event of a system issue, and more.

Continuous integration, continuous delivery, and continuous deployment implementations cover a wide range of automation possibilities for your software. This article will provide an overview of these three principles, the benefits they can bring to your engineering efficiency, and potential challenges.

At some point when you build applications with a wide user base, you find that you need to support various combinations of languages and locales. This could be in the form of having to support a locale from the browser, or maybe a user has defined their preferred locale in their profile, so you need to display data in a different locale from the browser default.

Jest is one of the most popular testing frameworks, but it hasn’t really kept up with the growing support for native JavaScript modules (ESM) in the developer community. A fresh install of Jest will simply not work with native modules.

You may not need a monorepo, but it’s useful to know what they are and what they have to offer. You could have a monorepo that is a mix of frontend, backend, utilities, linters, or more, each with its own set of build tools, and various needs.

How often have you wanted to yell at your computer or phone? What if your device could save that tirade as a text in an email or note you could review in the future, a memento of your favorite outbursts? Or, maybe you want to provide your users a more hands-free experience, with alerts that also speak to you. Or you simply want to add a clean voice-to-text component to your application.