React 18 Released: New Features Including Automatic Batching, Transitions, and Enhanced Suspense Support

React 18 is now officially released, bringing out‑of‑the‑box improvements such as automatic batching, a new API (e.g., startTransition ) and support for server‑side rendering with Suspense.

The announcement explains that many of the new features rely on a new concurrent renderer, an optional behind‑the‑scenes change that the React team believes will significantly impact how applications are built.

Developers can now use Suspense to fetch data in frameworks like Relay, Next.js, Hydrogen, or Remix. While technically feasible, using Suspense for data fetching is not yet recommended as a general strategy, though more primitives may be exposed in the future.

Key new features include:

Automatic Batching : React now groups multiple state updates into a single render, even when they occur inside promises, setTimeout , native event handlers, or other asynchronous contexts. The code example shows the difference before and after automatic batching.

Transitions : A new concept that separates urgent updates (e.g., typing) from non‑urgent UI transitions. The example demonstrates importing startTransition and using it to mark state updates as transitions.

Suspense Enhancements : Suspense can now declaratively specify loading states for any asynchronous operation, not just code loading. The provided JSX example shows a <Suspense fallback={<Spinner />}><Comments /></Suspense> pattern.

New Client and Server Rendering APIs : These changes allow developers to adopt the new APIs while still using the older React 17 APIs during migration.

Strict Mode Behaviors : React 18 introduces a development‑only check that mounts, unmounts, and remounts components to ensure they can handle multiple mount cycles gracefully.

The article also includes a visual illustration of the strict mode mounting sequence and an image summarizing the release.