Mastering React 19: Exploring the Latest Features of the New React Version
React 18 was a major milestone in the framework’s journey, primarily because of the introduction of an interruptible, cancelable, concurrent rendering engine. This feature improved UI rendering, improved the interactions with Server Side React (SSR), and paved the way for many new features to be built upon React’s shiny new innards.
React 19 fulfilled the promise set by React 18 by leveraging its interruptible and concurrent rendering engine to introduce Actions. These are a convention for handling Async data fetching within components. Building on the foundation of useTransition(), React 19 refines asynchronous interaction management and also introduces new hooks for Actions, form handling, and new features to React DOM’s <form> element.
Along with Actions, React 19 also introduced Server Components and Server Actions. This was a major milestone and an important improvement. It is a lot to cover in one article, though, so watch out for Part II that will explore Server Components and Server Actions in detail.
In this article, we’ll look at the major new features and functionality introduced in React 19. We’ll also discuss upgrading from React 18. With that, let’s dig in!
Table Of Contents
React 19 Actions
Let’s start with Actions, arguably the most significant update in React 19.
The React Blog defines Actions as follows:
By convention, functions that use async transitions are called 'Actions'.
An Action in React 19 is not in itself a hook or an API. Rather, it represents a convention for consolidating common code paths when handling async calls originating from within a component. React 19’s implementation of Actions improves the boilerplate code for handling pending states, optimistic updates, and error handling associated with async calls to a server.