Maciej Jastrzębski
1.8K posts
Maciej Jastrzębski
@mdj_dev
React Native at @callstackio — OSS: RN Testing Library — team console.log
Wroclaw, Poland Sumali Nisan 2020
130 Sinusundan3.1K Mga Tagasunod
gpt-5.4 achieves better results than gpt-5.3 with 3,5x less tokens 🤯
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Maciej Jastrzębski nag-retweet
Hello New York City! React Universe Conf is morphing into React Universe Summit.
New city, new format, and even sharper focus on trends emerging in React Native and AI Engineering today.
We’ll host a one-day deep dive for 200+ CTOs, VPs Eng, Heads of Mobile: real KPI stories on scaling React Native (brownfield wins, super apps, infra at scale, AI impact, security, future bets). Speakers from leading tech companies.
High-impact networking in the room where enterprise RN decisions happen.
Join us on June 23, 2026.
Tickets & partnership spots open 👇clstk.com/4b2J8SF
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Maciej Jastrzębski nag-retweet
Which AI coding model actually writes good React Native code? We couldn't prove it either, so we built a benchmark.
React Native Evals: 43 real-world tasks across animations, async state, and navigation.
Read more on our blog ⬇️
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Maciej Jastrzębski nag-retweet
This year we’re bringing the React Native community together in New York City 🇺🇸
React Universe Summit
📅 June 23, 2026
📍Tribeca Rooftop, NYC
Expect a curated program packed with practical knowledge:
→ Technical recommendations for scaling React Native
→ Fresh AI trends and efficiency gains in engineering teams
→ Battle-tested best practices to apply immediately
→ Hands-on insights, strong opinions, and hallway conversations that get you thinking
Tickets & partnerships are now open ⬇️
reactuniverse.com/?utm_campaign=…
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Announcing Hermes-node
Hermes can now run as a standalone CLI with Node.js-compatible APIs - no C++ embedding required.
Technically, hermes-node is a Node.js API compatibility layer for Hermes. It ports Node's native bindings (fs, net, http, child_process, etc.) to Node-API and reuses Node's original lib/*.js files, allowing standard Node.js programs to run on Hermes instead of V8. It vendors libuv, c-ares, llhttp, Ada, simdutf, etc to provide the same networking and I/O stack as Node, and runs as a standalone CLI binary.
In this demo:
- REPL with tab completion
- TypeScript HTTP server using http, fs, and path
- Type annotations stripped natively by the parser — no transpiler, not even a built-in one.
This is still a work in progress, though surprisingly functional. More Node modules coming, source will be published soon.
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Is TanStack Start for React Native in the works? 🤔
Every framework needs a router, right?
Tanner Linsley@tannerlinsley
Status update: TanStack Router running in React Native w/ Expo UI. Bit janky/buggy around React Native Screens still, but progress is being made.
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We should give it a shot in React Native Testing Library to make the test resemble real environment more using the same JS engine
Tzvetan Mikov@tmikov
Announcing Hermes-node Hermes can now run as a standalone CLI with Node.js-compatible APIs - no C++ embedding required. Technically, hermes-node is a Node.js API compatibility layer for Hermes. It ports Node's native bindings (fs, net, http, child_process, etc.) to Node-API and reuses Node's original lib/*.js files, allowing standard Node.js programs to run on Hermes instead of V8. It vendors libuv, c-ares, llhttp, Ada, simdutf, etc to provide the same networking and I/O stack as Node, and runs as a standalone CLI binary. In this demo: - REPL with tab completion - TypeScript HTTP server using http, fs, and path - Type annotations stripped natively by the parser — no transpiler, not even a built-in one. This is still a work in progress, though surprisingly functional. More Node modules coming, source will be published soon.
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Maciej Jastrzębski nag-retweet
TypeScript 6.0 beta is now published!
This release brings
- inference improvements for functions
- updates to package.json 'imports'
- the Temporal APIs
- alignments for the upcoming TypeScript 7.0
- & more!
Try it today!
devblogs.microsoft.com/typescript/ann…
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Maciej Jastrzębski nag-retweet
This Week In React 268:
⚛️
- Bulletproof Comps
- Render Types
- Tambo
- Logo Soup
- React Compiler
- Exit anims
- React Compiler
- React2AWS
- Ink
📱
- React Native 0.84
- Gesture Handler
- Rozenite
- Storybook
- JSON Render
- Targets
🍿 Read/subscribe: thisweekinreact.com/newsletter/268
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Maciej Jastrzębski nag-retweet
Upgrading React Native apps in 2026 couldn't be easier
Michał Pierzchała@thymikee
We've just released 𝚞𝚙𝚐𝚛𝚊𝚍𝚒𝚗𝚐-𝚛𝚎𝚊𝚌𝚝-𝚗𝚊𝚝𝚒𝚟𝚎 skill ✨ ~/ npx skills add callstackincubator/agent-skills
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Install it with skills CLI:
npx skills add github.com/callstack/reac… --skill react-native-testing
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React Native Testing Library now has an official agent skill! 🎉
It gives your agent full knowledge of RNTL so it can:
- Use every query, matcher, and event APIs correctly
- Apply best practices & detect anti-patterns
- Support both v13 and v14 beta
- Follow a11y-first testing
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Maciej Jastrzębski nag-retweet
Maciej Jastrzębski nag-retweet
We've just released 𝚞𝚙𝚐𝚛𝚊𝚍𝚒𝚗𝚐-𝚛𝚎𝚊𝚌𝚝-𝚗𝚊𝚝𝚒𝚟𝚎 skill ✨
~/ npx skills add callstackincubator/agent-skills
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@sephdk 1. RN has RCTSetImageCacheLimits
2. Manually calling global.gc() allows releasing of previous image rasters
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Turns out you can save 75% on memory use in a React Native apps. Expo Image vs React Native Image: github.com/scarlac/benchm…
What other libraries are worth comparing these days?
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Maciej Jastrzębski nag-retweet
Introducing Claude Opus 4.6. Our smartest model got an upgrade.
Opus 4.6 plans more carefully, sustains agentic tasks for longer, operates reliably in massive codebases, and catches its own mistakes.
It’s also our first Opus-class model with 1M token context in beta.
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... but you probably just need to run these 2 codemods:
- rntl-v14-update-deps
- rntl-v14-async-functions
In my tests, they handled ~95% of tests on large test bases.
Looking forward to your feedback 🙏
#codemods" target="_blank" rel="nofollow noopener">oss.callstack.com/react-native-t…
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I've made a Migration Guide explain what to change...
oss.callstack.com/react-native-t…
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React Native Testing Library v14 beta is now officially available! 🚀
This major version brings 2 significant changes:
🔹 New test-renderer package instead of deprecated React Test Rendere
🔹 Transition to async APIs: render, fireEvent, act, etc
Both are covered by codemods!
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