This Week In React #296: React 19.3, DevTools, Next.js, cn, Maps | 0.88 RC, Expo Modules, Navigation Benchmarks

Hi everyone, Seb and Jan here 👋!

We could feel it was coming, and here it is, ~~delaying~~ just in time for the newsletter! 😇

React 19.3 is finally out, with View Transitions and Fragment Refs stable! And it looks like updated DevTools are also coming soon.

We also got a sneak peek of React Native 0.88 and Expo Modules 2.0.

Let's dive in!

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⚛️ React

React 19.3

The new minor version of React is finally out, and it’s a great one!

If you read us regularly, we already disclosed everything 😇, but here’s a reminder of the highlights:

View Transitions: now stable! Also including the addTransitionType API that lets you customize the animation directly from the code triggering it.
Fragment Refs: now stable! This lets you get a ref of a <Fragment> and manipulate its underlying children DOM nodes. A quite useful feature unlocking new composition patterns that were previously difficult or requiring a wrapper DOM node.
use(browser()): a first-class API to opt out a subtree of server-side rendering, replacing patterns based on typeof window and useEffect.
Trusted Types: security feature to use in conjunction with Content-Security-Policy to prevent XSS attacks.
RSC can render <Context>: no need to create a wrapper <ContextProvider> component anymore.

Make sure to read that blog post because it contains interactive examples worth taking a look at, in particular to understand View Transitions and Fragment Refs.

💸 Sentry - How to wire a custom metric into a Next.js app, chart it, and alert on it. Learn how.
👀 React DevTools 8.0 - Suspense Tab enabled, React Element panel, remove Timeline profiler in favor of Performance tracks, display dimmed Activity subtree - The v8 changelog is already merged and gives a sneak peek. Not published yet on npm or extension stores.
👀 React DevTools CDT MCP - Speaking of DevTools, the React team is also experimenting with a new package, recently published to npm. It’s not an MCP server, but lets Chrome DevTools discover/register/expose React tools useful for agents to understand and profile your app at runtime.
👀 React.dev PR - Document missing SSR and hydration options - Adding the missing API ref documentation for SSR options such as formState, importMap, maxHeadersLength.
👀 Next.js PR - Upgrade web-vitals to v6 and report soft navigations - useReportWebVitals() will soon report SPA soft navigations, recently included in Core Web Vitals.
📜 React Now Rusted All The Way Out - An overview of the React Compiler in Rust landing in Vite, reporting a 17x speedup over the Babel version, and giving an alternative solution for React Router framework mode users.
📜 Replacing Next.js with a vibe-coded "framework" - Replacing Next.js on a personal site with a 5k-line framework Claude architected. Still React/MDX on the server, Preact islands on the client, with 99% less JS shipped. This shows meta-frameworks could eventually die out: their knowledge can be distilled into skills instead, and custom frameworks can be created on demand.
📜 Next.js - How Turbopack chunks your JavaScript - Explains the trade-offs behind code splitting strategies and the heuristics used to minimize both download size and request count. Next.js 16.3 comes with experimental options to optimize chunking and fine-tune heuristics based on your site access patterns.
📜 Next.js- How we closed 1,500 GitHub issues in one month - No React lesson here: they built an agent to analyze backlog issues to help maintainers close thousands of issues with confidence.
💸 Prepathon by Cloudways - Virtual Event - Sep 22 & 23 - Two days of sessions and hands-on activities on AI-assisted building, modern deployment, and what's actually working for developers shipping fast right now. Free to join from anywhere in the world. Register now to save your spot.
📦 React Google Maps 1.10 - New new 3d components - The library completed its existing Google Maps 3D support with declarative components for GLB models, HTML markers, polylines, polygons, terrain flattening, and circular paths. A demo is worth a thousand words, so check this 3D Maps Markers demo to see fancy 3D markers, including an animated Model3D Balloon.
📦 cn - A new engine for Tailwind class merging and conflict resolution - Claims to be 30x faster than tailwind-merge + clsx with the same APIs. Already integrated in shadcn 4.21. Use npx shadcn migrate cn to migrate. Faster, but 26 KB minified; can be reduced with cn build.
📦 Effective RSC - An experimental, Effect-native React Server Components framework for Bun - Ideas are worth taking a look at. RSC pages are Effect.fn() functions with Schema-decoded route params. Effect unlocks various benefits for RSCs, such as type-safe dependency injection and error handling, or request abortion propagation.
📦 Vidact - Compiles React code to direct DOM operations - In beta, supporting a growing subset of React 19. Components run only once when they mount.
📦 uf - Unified Toolchain for Flow and React - A Rust-based toolchain comparable to Vite+, improving DX for React and Flow. The author’s arguments are worth reading: Flow is a more precise type system than TypeScript for describing React code.
📦 DevJar 1.0 - React live code playgrounds - An interesting alternative to CodeSandbox to embed interactive React-based experiences on your site.
📦 Bamboo CSS - Zero-runtime CSS-in-JS - A Vite compiler erases the runtime, prunes unused tokens, and fails the build on invalid tokens.
📦 Base UI 1.8 - Improves mount perf for Menu/Popover, Combobox.createItems() API, Avatar lazy-loading
📦 Rsbuild Plugin React Router 0.6 - Support React Router 8 and its RSC mode
📦 Storybook 10.6 - TanStack / NextJS-Vite framework fixes, CLI bindings for agent tools/skills, performance improvements
📦 React Window 2.3 - New optional rowKey/columnKey props
📦 Jotai 3.0 - Modernized ESM-only package, removing deprecated APIs

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