What’s the best way for a frontend developer to switch to backend or fullstack?

Consider learning Ruby on Rails. It’s a very structured framework with established best practices, making it easier for beginners to learn how to do things the right way. Even if its popularity has cooled off a little, many big sites still rely on it, and picking up Ruby after JavaScript can be a breeze!

Don’t overlook REST APIs! Knowing how to build and interact with them is critical for backend roles. Also, a lot of job listings favor knowledge in PHP and Laravel if you're looking at the fullstack option, especially in web applications.

I suggest picking a backend language like Node.js since you already know JavaScript. Focus on user and session management, HTTP basics, and popular frameworks that come with those languages. Understanding Relational Database Management Systems (RDBMS) is essential too. This will give you a strong foundation for backend development.

If you're coming from a frontend background, a great starting point is to stick with JavaScript and dive into Node.js. Build a simple CRUD application that connects to your frontend through API calls. After that, get familiar with databases; start with Object-Relational Mappers (ORMs) which simplify database interactions, then gradually learn SQL for deeper understanding. Don't forget to containerize your app with Docker, and once you're comfortable, explore deploying it to a cloud service like AWS or Azure. This path can transform you into a fullstack developer in no time!