This Week In React #267 : Bun, Next-Intl, Grab, Aria | Worklets, Teleport, Voltra, AI SDK, Screens | State of JS, Temporal

#react #reactnative

Hi everyone!

You’ll have to get used to it: yet another week filled with AI content. From MCPs to Agent Skills to AI-specific CLIs, we don’t know where to turn anymore.

We’re delighted to be ranked once again among the top 5 newsletters in the State of JavaScript 2025 survey. Thanks for your trust!

By the way, we’d love your feedback — what do you like about the newsletter, and how could we make it better in 2026?

Just hit reply and let us know! ❤️

💡 Subscribe to the official newsletter to receive an email every week!

💸 Sponsor

React Performance, v2

Make React apps fast where it actually matters.

An advanced performance course from Steve Kinney, focused on diagnosing real bottlenecks and fixing slow, janky React apps using modern React 19 patterns.

🚀 Modern React: Suspense, transitions, deferred values, hydration, server actions
🔍 Debug Faster: Find unnecessary re-renders with React DevTools & the Profiler
🧠 Smart Optimization: Memoization, virtualization, code splitting, optimistic UI
⚡ Feel-Fast UX: Learn how React Fiber prioritizes work to keep apps responsive

⏱ 4+ hours • ⭐ 4.8 rating

🏫 From Frontend Masters\
👉 Watch the course: https://frontendmasters.com/courses/react-performance-v2/

⚛️ React

💸 PostHog - 8 learnings from 1 year of agents
👀 React DOM PR - Support for SubmitEvent.submitter
👀 React.dev PRs - Revamp docs of useOptimistic, useActionState, and useEffectEvent.
📜 React’s ViewTransition Element - Chris Coyier compares the pros and cons of using <ViewTransition> VS the native platform API document.startViewTransition() in a React app.
📜 Why Inngest migrated off Next.js to TanStack Start - Reducing local dev time by 83% - Ingress was an early adopter of RSCs but got bitten by them, experienced slow local DX despite using Turbopack. They share their migration strategy and lessons learned.
📜 Reverse-Engineering Figma Make: Extracting React Apps from Binary Files - Figma Make uses React, Radix UI, and Tailwind under the hood, and you can recreate the underlying React app from .fig files.
📜 The engineering behind GitHub Copilot CLI’s animated ASCII banner - Rendering reliable animated components to the terminal UI looks complex, even if you leverage the React Ink renderer.
📜 Can AI actually debug complex React/Next.js issues? - Throwing 3 real-world bugs at Claude Opus, it could only fix one properly.
📜 React design system library MCP - How to leverage the experimental Storybook MCP server
💸 Building AI Voice Agents at Scale — The executive playbook by ElevenLabs
📦 Next Intl 4.8 - Ahead-of-time compilation - This can significantly reduce your bundle size. Instead of bundling a full ICU parser to the client, it’s now possible to precompile ICU messages to a minified AST interpreted by a lightweight runtime.
📦 Bun 1.3.8 - Bun.markdown API - Comes with a first-class Bun.markdown.react() API and claims to be much faster than React alternatives.
📦 React Grab 1.0 - Select context for coding agents directly from the website - A convenient tool can make your coding agent 3x faster thanks to more precise prompts.
📦 shadcn/ui updates - RTL support, unified Radix UI Package
📦 React Aria 1.15 - New render prop, Agent Skills, constrain dates on blur
📦 Gatsby 5.16 - Add support for React 19 and Node 24
📦 Rspress 2.0 - Documentation framework - Theme styling, AI-native, Shiki highlighting, performance, new plugins
📦 React Three Fiber 10.0 alpha - Backward compatible, WebGPU support, TSL hooks, new scheduler
📦 Travels 1.0 - Fast, framework-agnostic undo/redo library with React integrations
📦 Prefill - Partial application for React components
📦 Meteor 3.4 - Rspack integration, 4x faster builds, 8x smaller bundles, and extended bundler features
📦 ESLint React 2.9 - Extract React RSC sub-plugin, new RSC preset
📦 Rsbuild Plugin React Router 0.1 - Behavior closer to React Router's official Vite plugin
🤖 React Router Agent Skills
🤖 React Composition Patterns Agent Skills
🎥 Toby Mey - Where to put Auth in Next.js 16?
🎥 Remotion - Create motion graphics with AI – Simple tutorial for beginners

💸 Sponsor

Still writing tests manually?

Notion, Dropbox and LaunchDarkly have found a new testing paradigm - and they can't imagine working without it. Built by ex-Palantir engineers, Meticulous autonomously creates a continuously evolving suite of E2E UI tests that delivers near-exhaustive coverage with zero developer effort - impossible to deliver by any other means.

It works like magic in the background:

Near-exhaustive coverage on every test run
No test creation
No maintenance (seriously)
Zero flakes (built on a deterministic browser)

🤨 Curious? Book in a time to learn more

📱 React-Native

Behind the Scenes of React Native Multithreading: Vision Camera V5 x React Native Worklets

Worklets have been extracted from Reanimated to become a first-class multithreading primitive. It has been integrated into the upcoming VisionCamera V5, enabling its real-time frame processor system to run directly on the Camera Thread.

Also, take a look at 📦 Worklets 0.8 - Bundle Mode preview. It makes it possible to use third-party libraries and do network requests within worklets. This mode is opt-in but might become the default in the future.

💸 Stop searching for components manually - try the Element Inspector in Radon to build React Native apps faster.
📜 Building Voltra: Renderer - The creator of the Widgets and Live Activities library explains how it works under the hood. It’s a custom renderer, but using react-reconciler wasn’t a great fit, so they took inspiration from React DOM SSR code instead.
📜 5 tips to increase mobile app downloads and retention in 2026
📦 Teleport 1.0 - Brings true native portals to React Native - The equivalent of ReactDOM.createPortal for mobile, with additional view re-parenting, re-use, and pre-rendering capabilities. It’s cross-platform and also supports web.
📦 Screens 4.21 - Android stack screen preloading, iOS xcassets icon catalogs support for key navigation UI elements - Note that iOS xcassets icon catalogs are already integrated into React Navigation for native tabs.
📦 Xcode 26.3 RC - Unlocks the power of agentic coding - If you don’t want to use Xcode as an IDE, you can still leverage the new Xcode MCP and its RenderPreview tool to feed your AI with visual feedback (SwiftUI previews, it probably doesn’t work with RN views).
📦 Agent-Device - CLI to control iOS and Android devices for AI agents - The equivalent of Vercel’s agent-browser for mobile. Support for TV/desktop apps planned.
📦 AI SDK Profiler - New Rozenite DevTools plugin - Lets you inspect OpenTelemetry spans coming from the RN AI SDK
📦 AI SDK 0.12 - Profiler plugin, ai v6, tool calling and re-ranking for Llama models
📦 Tamagui 2.0 RC - Universal style library for React - More stable, easy, documented, fast, and feature-complete
📦 Uniwind 1.3 - Support data attributes
📦 Superconfig - 18x faster than react-native-config, using Nitro
🎥 Callstack - Implementing an Android TurboModule from Scratch
🎥 React Native Live - New monthly live show channel from Infinite Red
🎥 Beto - Are You Leaking Your Environment Variables? React Native + Expo
🎥 Simon Grimm - 10 Tips You Need For Expo Router in 2026!
🎙️ RNR 352 - Expo Launch with Cedric van Putten

🔀 Other

📊 State of JavaScript 2025 - Survey Results - React and Next.js keep growing in usage, but satisfaction is decreasing. Meanwhile, alternatives such as Astro and Solid have pretty high satisfaction scores.
📜 Implementing the Temporal proposal in JavaScriptCore - The JS Temporal API should be in all browsers relatively soon, with Safari being the last remaining browser. The implementation for JSC (Safari, Bun) is complete but not merged yet.
📜 Node.js Path Traversal: Prevention & Security Guide - Explains how to secure your Node app from unsafe path inputs, such as http://localhost:port/images/../../etc/passwd.
📜 Building a browser API in one shot - With a good prompt created by an expert, Claude Opus can one-shot a decent TypeScript implementation of IndexedDB.
📦 Astro 5.17 - Dev toolbar placement, partitioned cookie, async file loader parser
📦 Turborepo 2.8 - Git worktree support, Agent skills, AI-enabled
📦 Babel 7.29 - The last Babel 7 minor release - They are also announcing Babel 8 in RC, aiming to be easy to adopt, and ESM-only.
🔗 npmx - A fast, modern browser for the npm registry