If you're a JavaScript developer, you may have heard about the buzz around signals lately. Several popular JavaScript frameworks, such as Vue, Preact, Solid, Angular, and Quick, have recently implemented and supported the use of signals. But what exactly are signals? As web applications become more complex, managing the state of JavaScript applications becomes a challenge. This is where signals can be a valuable tool, allowing the application to respond to changes in the state, such as a variable change. In this article, we will explore the concept of signals and how they can be used in Vanilla JavaScript applications. We will use the Vue and Preact reactivity libraries and see how easy and similar these two approaches are to implement. For the demo project, we will use Vite. So let's get started by creating a Vite app.

Firebase is a great platform that offers a wide range of services to developers, making it easy to build, improve, and grow their apps. One of these services is Firebase Auth, which allows for easy user authentication using its JavaScript SDK. Despite Firebase Auth being an awesome service and abstracting a lot of the complex code needed to build user authentication, I recently found one limitation. Firebase Auth doesn't persist the session across multiple domains. This means that if we use the same Firebase Auth for two different domains, such as https://example1.com and https://example2.com, we have to sign in to both applications on both domains independently. Currently, Firebase doesn't have a built-in feature to handle this situation out of the box.