This Week In React #258: TanStack, Next.js | Valdi, IntersectionObserver, Nitro | TC39, Node

#react #reactnative

Hi everyone, Seb here! 👋

This week has been relatively calm in the ecosystem. We have a good variety of community blog posts, releases, and weak signals. I'm not sure what to highlight, so I'll just let you enjoy reading it!

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TanStack DB 0.5 — Query-Driven Sync

A collection shouldn't dictate what data loads: Your queries should. This concept is now implemented in TanStack DB with a new syncMode: ‘eager’ | ‘on-demand’ | ‘progressive’ option. This moves the library closer to how GraphQL clients like Apollo/Relay work, where components declare their data dependency, and the client figures out how to load and maintain that data. This can be adapted to work on top of any existing backend API, as long as you provide code to map the query predicates into actual API calls.

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📣 Both Bun and Vercel announced TanStack Start support, leveraging the Nitro Vite plugin.
👀 Next.js PR - New config.experimental.transitionIndicator option: This turns on an experimental React Transition Indicator feature to trigger your browser's native spinner during pending React transitions. It’s still early, and should only work in Chromium, but I’m excited to give it a try asap!
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📜 React 19 Error Boundary Behaves Differently: Explains a subtle Error Boundary behavior change that came with React 19, implementing a fail-fast behavior that bails out on the first error instead of aggregating errors.
📜 Dead Framework Theory: New frameworks are dead on arrival in a world where React has become the platform. LLMs output React code by default and/or due to hardcoded system prompts, creating a self-reinforcing loop that hinders innovation.
📜 StyleX: A Styling Library for CSS at Scale: StyleX maintainer gives a nice overview of Meta’s CSS-in-JS library.
📜 The Illusion of Language: What Directives Really Are: Compares directives to C++ pragmas/macros, and tells us what we can learn from history.
📜 Vercel: The anti-vendor-lock-in cloud: Vercel argues that a framework-defined infrastructure creates more portable code and less lock-in. Next.js adapters formalize the framework-platform contract.
📜 Everything you need to know about act() in React tests: A deep dive on the test helper function that ensures React pending updates are applied before making assertions.
📜 Don't Blindly Use useTransition Everywhere: An interactive blog post explains that the UX of a React docs example is not ideal (switching tabs with expensive content), and suggests an improvement.
📜 Error Handling in React with react-error-boundary: The lib provides a declarative error boundary component for rendering errors, and you can also use useErrorBoundary() to trigger it imperatively.
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📦 ImGui React Runtime: Hermes maintainer created a custom runtime and React renderer for Dear ImGui (C++ GUI lib). Experimental, but clearly shows Static Hermes' ability to mix typed and untyped JS in a single project, while enabling direct, zero-cost FFI bindings to the underlying C++ lib.
📦 Next-Intl 4.5 - Introducing useExtracted(): The Tailwind of i18n: This new API is an attempt to bring Tailwind properties (colocation, local reasoning, no naming…) to i18n, improving AI support along the way.
📦 React Email 5.0 - Support for dark mode, Tailwind 4, new components, React 19.2, Next.js 16
📦 React Router 7.9.5 - Unstable instrumentation API, unstable concurrent prerendering
📦 Ink 6.5 - CLI renderer - New incremental rendering mode to only updates changed lines
🎥 Shruti Kapoor - 4 Features of React 19.2 You Must Know
🎙️ Syntax.fm 954 - Fullstack TanStack! The Scoop with Tanner Linsley

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📱 React-Native

Valdi - Cross-platform UI framework

Snapchat released a beta version of the cross-platform UI framework they've used in production apps for the last 8 years. It’s not based on React, but also uses a similar declarative model and relies on the Yoga layout engine. TypeScript components are compiled directly to native iOS, Android, and macOS views.

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