About React 19

(Optional lesson)

In December 2024, the long-awaited React 19 update became stable. 🎉

Lots of students have reached out to ask if this course has been updated for React 19 / Next.js 15. I’m pleased to share that this course has mostly been updated!

In this brief lesson, I’ll share exactly what I mean by “mostly”, but first, let me reassure you: this course is still 100% relevant for software developers using React today. I genuinely do not believe you need to be concerned about this.

To quickly summarize what has changed in React 19, I think there are 3 main buckets:

1. Minor improvements and tweaks
2. The stabilization of Server Components
3. The introduction of “Actions”

(There were also a bunch of under-the-hood changes, but those only really affect framework/library maintainers, so I’ve excluded them from this list.)

Let’s look at each bucket in turn.

React 19 introduces a handful of “quality of life” changes, tweaking things to be slightly more ergonomic.

The Joy of React has been updated to include these changes. I’ve added notes throughout the course to highlight and explain changes in React 19. I’ve also updated the playgrounds and projects to use React 19 as well, so you can experiment with these changes on this platform.

These changes are all pretty minor, but I’ve made sure that you won’t miss any of them as you go through the course!

Server Components is one of the two headline features for React 19. And good news: we already cover them in The Joy of React!

How is that possible? Well, Server Components were released in “beta” in React 18. They’ve been marked as stable in React 19, but their public API hasn’t changed at all.

So when it comes to this particular bleeding-edge feature, this course is already 100% up to date. 😄

The new Actions API is the other headline feature for React 19. They offer an alternative way to work with forms and perform mutations.

This is the biggest thing missing from The Joy of React right now: we don’t really cover Actions at all. It’s very possible that I’ll add some content in the future to fill this gap, but at least for now, I’m in “wait and see” mode. I want to see if the community adopts them or not.

I’ve done some experimenting with Actions, and truthfully, it isn’t clear to me that it’s really an improvement over the existing alternatives. I’ll be watching to see whether companies start using them, whether it becomes a thing you need to know as a React developer.

In Module 6 of this course, we cover full-stack React principles in the context of Next.js’ new App Router.

Next.js recently released a new major version, 15. This release was largely about bumping React from 18 to 19, though there were also some breaking changes.

I’m pleased to share that this course has been fully updated for Next 15. In Module 6, all of the code has been updated, and notes have been added that highlight recent changes.

Over the summer, I built a brand-new version of my blog, joshwcomeau.com (opens in new tab). I used React 19 (while it was still in beta), because I wanted to learn all the new stuff.

And honestly, React 19 feels exactly like React 18 most of the time. I was able to benefit from some of the quality-of-life improvements, and I had fun experimenting with Actions, but the overwhelming majority of things were completely identical.

As I mentioned above, the course now highlights the things that have changed in React 19 / Next 15, so you won’t miss out on any new goodies. But for the most part, React is still React, and the stuff you learn in this course will serve you in your career for years to come. 💖