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T.J. Żelawski

@tjzel.dev
157 followers 70 following 32 posts

Software Engineer @Software Mansion I maintain some React Native open-source libraries

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T.J. Żelawski @tjzel.dev · 23/09/2026
I'll be speaking at ReactCon Berlin this October! If you're crazy about low-level stuff like me and want to know just how much overhead the JavaScript layer adds in React Native apps, don't miss my talk!
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T.J. Żelawski @tjzel.dev · 25/08/2025
I'm excited to announce I will be speaker at React Universe, just next week! 🥳 It's high time we talk Worklets on a big stage.
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T.J. Żelawski @tjzel.dev · 16/08/2025
why use expo plugin if you can use the website instead downloadmoreram.com
downloadmoreram.com
DownloadMoreRAM.com - CloudRAM 2.0
DownloadMoreRAM.com - CloudRAM 2.0
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Reposted by T.J. Żelawski
Iwo Plaza | TypeGPU @iwoplaza.dev · 24/07/2025
My talk titled "Your GPU is a JavaScript Runtime*" just landed on YouTube! 👨‍💻 I answer WHY and HOW we compile JS/TS to WGSL, how it improves interop for the whole ecosystem, and the added dimension of customizability it unlocks for WebGPU libraries Video below ⬇️ #webgpu #typegpu #typescript
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T.J. Żelawski @tjzel.dev · 23/07/2025
It's our biggest one yet!
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T.J. Żelawski @tjzel.dev · 21/07/2025
sadly it's literally impossible to make a 100% working anti-cheat
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T.J. Żelawski @tjzel.dev · 15/07/2025
Code of the app in the clip can be found here github.com/software-man...
github.com
GitHub - software-mansion-labs/Bundle-Mode-showcase-app
Contribute to software-mansion-labs/Bundle-Mode-showcase-app development by creating an account on GitHub.
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T.J. Żelawski @tjzel.dev · 15/07/2025
If you want to test it in your app, keep in mind that Reanimated 3 doesn't work with standalone `react-native-worklets`. However, a nightly version of Reanimated 4 works just fine.
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T.J. Żelawski @tjzel.dev · 15/07/2025
Libraries that fetch data will also have a hard time - `fetch` is not yet available on Worklet Runtimes. We aim to add it soon™. For now, libraries that focus on the UI are the best bet to use with Bundle Mode - like `react-native-wgpu` or `react-native-live-markdown`.
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T.J. Żelawski @tjzel.dev · 15/07/2025
While the feature allows you to use virtually any library, there are some constraints. For example, some side-effects are problematic. A library that would directly import React Native can't be used on a Worklet Runtime. Don't worry, you will get a friendly error in that case.
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T.J. Żelawski @tjzel.dev · 15/07/2025
Ultimately this will be a plug-and-play solution, without cumbersome configurations. However, it's not that simple. Bundle Mode needs APIs that aren't yet available in React Native. Please give a thumbs up on my PR so we can ship it to React Native faster github.com/facebook/rea...
github.com
proposal: BundleConsumer interface for TurboModules by tjzel · Pull Request #50788 · facebook/react-native
Summary: With the development of react-native-worklets library I want to align it more with the tools inside React Native ecosystem and reduce the amount of hacks needed to provide multithreading J...
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T.J. Żelawski @tjzel.dev · 15/07/2025
To run it, you need to install `react-native-worklets@bundle-mode-preview` and apply some patches to React Native, which expose additional APIs. The patches are non-invasive and won't change your app's behavior outside of worklets. More in the docs docs.swmansion.com/react-native...
docs.swmansion.com
Bundle Mode | React Native Worklets
Bundle Mode is a feature that gives worklets access to your whole JavaScript bundle - meaning that any code that's present in the bundle can be executed in any worklet and on any runtime. This means t...
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T.J. Żelawski @tjzel.dev · 15/07/2025
Every package you import in your application will be available to use in worklets. We call this feature "Bundle Mode". This is so because worklets and your app now share the very same JavaScript bundle.
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T.J. Żelawski @tjzel.dev · 15/07/2025
We did it! You can finally use third-party libraries in worklets - with `react-native-worklets`. Jump in the thread to learn more 👇
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Kræn Hansen 🇩🇰 @kraenhansen.dk · 10/07/2025
Announcing Node-API Support for React Native callstack.com/blog/announc... #reactnative #nodejs
callstack.com
Announcing Node-API Support for React Native
We are bringing Node-API to React Native to simplify native module development. Learn why this ABI-stable, cross-runtime system could replace JSI and unlock faster builds, better maintainability, and ...
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Reposted by T.J. Żelawski
Software Mansion @swmansion.com · 04/06/2025
The truth is… you don’t always need react-native-svg. 💥 Sometimes there’s just a better way to get the job done. 👀 www.youtube.com/shorts/IiSdp...
youtube.com
You Might Not Need react-native-svg #reactnative
YouTube video by Software Mansion
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T.J. Żelawski @tjzel.dev · 03/06/2025
I wish I could just pay for 30 days upfront without subscribing
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Reposted by T.J. Żelawski
Kacper Kapuściak @kacperkapusciak.bsky.social · 08/05/2025
This is Radon AI ✨ A GitHub Copilot Chat but with the latest knowledge of the React Native ecosystem. Let me know what you think!
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T.J. Żelawski @tjzel.dev · 24/03/2025
I loved the Revolver but wth was that Number9 thing
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T.J. Żelawski @tjzel.dev · 19/03/2025
@samuel.bsky.team can we have a better separation between "Show more like this" and "Show less like this"? The buttons are quite small and I often fat-finger the wrong one trying to customize my feed 😢
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T.J. Żelawski @tjzel.dev · 19/03/2025
There's an RFC for the new `react-native-worklets` library in case you missed it 🚀 github.com/software-man...
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T.J. Żelawski @tjzel.dev · 10/03/2025
We've been cooking 🧑‍🍳
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T.J. Żelawski @tjzel.dev · 20/02/2025
Made me think of
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T.J. Żelawski @tjzel.dev · 11/02/2025
C++ enjoyers, is there some syntax sugar to reduce boilerplate of `weak_ptr` locking in memory-safe lambdas referencing `this`? I'm tired of making the `return` block everytime and I don't want to nest either.
AnimationFrameBatchinator::JsiRequestAnimationFrame
AnimationFrameBatchinator::getJsiRequestAnimationFrame() {
  return [weakThis = weak_from_this()](
             facebook::jsi::Runtime &rt, const facebook::jsi::Value &callback) {
    const auto strongThis = weakThis.lock();
    if (!strongThis) {
      return;
    }

    strongThis->addToBatch(callback);
    strongThis->flush();
  };
}
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T.J. Żelawski @tjzel.dev · 06/02/2025
People digging up stuff like this is why I love open source. github.com/facebook/her... The issue sounds bizarre and funny, but when you think about it, it might actually affect you under the most unexpected circumstances.
github.com
Date.toLocaleString() is off by 2 days for dates before 1582. · Issue #1570 · facebook/hermes
Bug Description For very old dates, such as "0004-04-13T00:00:00Z", the .toLocaleString() will make the date string off by two days. i.e. it will be April 15 instead of April 13. I have run gradle ...
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T.J. Żelawski @tjzel.dev · 26/11/2024
embrace Patch Package Driven Development
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T.J. Żelawski @tjzel.dev · 25/11/2024
Hi William 👋
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T.J. Żelawski @tjzel.dev · 20/11/2024
You can install it using the 'next' tag: react-native-reanimated@next
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T.J. Żelawski @tjzel.dev · 20/11/2024
We have just released an RC version of Reanimated, 3.17.0-rc.0 🥳 It has significant changes in the native code structure. It's an important milestone for our goal of moving Worklets to a separate library. If you can, please check if it compiles in your project 🙏 All feedback is welcome!
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T.J. Żelawski @tjzel.dev · 19/11/2024
@danabra.mov is working too fast for us Reanimated developers to catch up with him 😅
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T.J. Żelawski @tjzel.dev · 17/11/2024
The @swmansion.com elephants love my kids 👶
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T.J. Żelawski @tjzel.dev · 15/11/2024
Aesthetically pleasing notes 🌺
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T.J. Żelawski @tjzel.dev · 15/11/2024
🤫
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T.J. Żelawski @tjzel.dev · 15/11/2024
Awesome job guys, rooting for RNLConf2025!
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T.J. Żelawski @tjzel.dev · 12/11/2024
Let me look into it tomorrow 😎
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T.J. Żelawski @tjzel.dev · 31/03/2024
Willem Dafoe is back?
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