📨 #296: React 19.3, DevTools, Next.js, cn, Maps, Effective-RSC, Vidact, uf | 0.88 RC, Expo Modules, Navigation Benchmarks, QuickJS, Goldie, ContinuedTask | Rslib, Vitest, gpu-lexer, Ata, Interop

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!

As always, thanks for supporting us on your favorite platform:

• 🦋 Bluesky
• ✖️ X / Twitter
• 👔 LinkedIn
• 👽 Reddit

Ne manque pas le prochain email !

I'm constantly finding interesting things to learn in there.

Dominik DorfmeisterWeb Developer - React-Query maintainer

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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

Ne manque pas le prochain email !

It's exceptionally well curated, offers great insights and is well worth subscribing to!

Addy OsmaniHead of Chrome DX - Google

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📱 React-Native

• 💸 build mode - Stop being the code review bottleneck
• 👀 RN 0.88 RC - SwiftPM tooling, DevTools screenshots, ArrayBuffer in TurboModules, Babel Platform inlining improvement, iOS SceneDelegate lifecycle - A sneak peek of the upcoming version from its changelog. Set up SwiftPM via npx react-native spm. Opt-in flags to drop legacy module/component interop will become the default later. Improved Platform.OS/select() inlining unlocks more platform-specific dead code elimination, around 𝕏 17.7KB on iOS and 19.6KB on Android.
• 📣 Expo Go - Login is now required to run projects - iOS-only for now. Will also be applied to Android later.
• 📊 React Native Navigation Benchmarks - Benchmarks the same app rebuilt 4x with different routers, covering cold start, RAM, FPS, and JS measurements. Android tests highlight the most common RN bottleneck.
• 📜 An early look at Expo Modules 2.0 - Modules become plain annotated Swift/Kotlin with no definition() DSL to learn. Sync calls run 2.5-5.6x faster than 1.0 on the same SDK and beat TurboModules in the Expo chart. Experimental, iOS-only. Android in progress.
• 💸 Codemagic Patch - The easiest way to run your own OTA update server, including dashboard and fingerprinting
• 📦 RN QuickJS alpha - Hermes-compatible JSI runtime - An alternative to Hermes. A tiny (~1.5MB) JavaScript engine that compiles to small bytecode bundles for faster startup, with a compatibility layer so most Hermes-dependent libs like Reanimated keep working without changes.
• 📦 Goldie - App Store screenshot generator for coding agents and humans - Useful framework-agnostic mobile tool. Argent replays flows; Goldie prepares store-compliant screenshots and preview videos.
• 📦 RN Continued Task - Background tasks that keep running after your app is backgrounded - One typed API over iOS 26 BGContinuedProcessingTask (Live Activity) + Android WorkManager foreground service, via Nitro. Useful for long-running user-initiated tasks like large exports, uploads, or encoding.
• 📦 Boost 1.7 - Image optimizer now default, RN 0.86 support
• 📦 Rozenite 2.4 - Auto-inject Lynx runtime, one endpoint for debug targets
• 📦 Sentry 8.25 - Feature flag info on native crashes, app.start vitals propagation
• 📦 Argent 0.24 - Physical iOS device support
• 📦 Uniwind 1.12 - Drop-shadow filter
• 📦 Streamdown 0.3 - Worklets 0.10 support
• 📦 Metro MCP 0.15 - MCP SDK v2, safer CDP reconnects pinned to same app, Hermes eval, Appium test gen
• 📦 Agent-Device 0.21 - Human takeovers in remote sessions, faster iOS Simulator opens, install size halved
• 📦 ReactLynx 0.126 - Now on Preact 11, 14% faster background renders, use() support
• 📦 Screen Choreography 0.4 - Shared-element transitions for Expo Router
• 🎙️ React Universe on Air - Running AI in the Browser With Transformers.js

🔀 Other

• 🗳️ Interop 2027 - Submit and vote for your favorite proposals
• 📜 Running zod Schemas on simdjson - Combining zod with ata, a JSON Schema engine using simdjson native core, and the benefits this brings.
• 📜 Half Past Fetch - await fetch() only waits for the headers, not the actual body, and other interesting details.
• 📜 Async Solid - 3-part series: reads, writes, and network
• 📦 gpu-lexer - Language-agnostic WebGPU syntax highlighter - Crazy idea! Highlighting is not based on language grammars but on a small AI model trained for this purpose.
• 📦 Rslib 1.0 - Multiple output formats, multi-framework support, bundled or bundleless, style/asset support, and more - Looks like an interesting tool, in particular for publishing a component library across many frameworks.
• 📦 Vitest 5.0 - Perf improvements, vi.when, Trace View in Browser Mode, benchmarking API, better defaults, and more
• 📦 htmx 4.0 - fetch() replaces XHR, explicit inheritance, swaps all HTTP responses, and other breaking changes
• 📦 NestJS 12.0 - ESM-first, Rspack replacing webpack, Standard Schema validation, observability SDK
• 📦 Playwright 1.63 - Test locks, Locator improvements, aria/screen snapshots in traces, and more

🤭 Fun

See ya! 👋