iiinova — where your digital self keeps evolving

Szymon Chmal @chmal.it · 20/10/2025

The Jest integration I sneak-peeked earlier is also letting me roll out code coverage support. The coverage reporter is already in place. I just had to instrument the code and send the coverage data from the device back to the CLI. Surprisingly, it was really easy to implement!

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Szymon Chmal @chmal.it · 17/10/2025

Expect it to be included in the next Harness release! With it, I can leverage Jest's infrastructure, such as built-in reporters, and potentially support running the same test suite in parallel across multiple devices. Huge thanks to @thymikee.bsky.social for pitching the idea at React Conf!

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Szymon Chmal @chmal.it · 17/10/2025

Harness isn't a simple tool - it's a bunch of components working together to give the best DX for testing JS code with native modules. Maintaining all that as a solo dev isn't easy, so I tried offloading some work by using Jest's CLI to run Harness… and it worked!

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Szymon Chmal @chmal.it · 16/10/2025

We're hosting a livestream today, with a special focus on React Native Harness! Expect insider insights on how it all works and sneak peeks at what's coming next. 🗓️ Thu 16, 5 PM CEST See you there!

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Szymon Chmal @chmal.it · 15/10/2025

Designed for library authors and teams building native integrations. It is cross-platform, works on CI/CD and made to test real native behavior with a familiar workflow.

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Szymon Chmal @chmal.it · 15/10/2025

Harness runs wherever Metro runs, starting with iOS and Android. It's built to be portable, making support for new platforms straightforward. As proof, we're also bringing support for VegaOS.

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Szymon Chmal @chmal.it · 15/10/2025

Harness runs tests in a real React Native runtime. Unlike Jest, it doesn't rely on mocks and unlike Detox or Maestro, it focuses on testing native code directly, not automating UI flows.

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Szymon Chmal @chmal.it · 15/10/2025

🎉 Introducing React Native Harness - a lightweight framework for testing native modules directly on device or emulator. Write tests in a Jest-like syntax, run them in a real React Native runtime, and verify native behavior without mocks.

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Szymon Chmal @chmal.it · 12/08/2025

Are you using the Performance API in React Native? If yes, I'm pretty sure you've wished a bunch of times that you could check out measures like you do in Chrome DevTools. What if I told you Rozenite is about to bring you that same vibe? Hot or not?

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Szymon Chmal @chmal.it · 06/08/2025

Yesterday, the community requested server-side event support for Rozenite's Network Activity. I said I'd look into it… but somehow ended up pushing a branch with the feature almost done. Whoops! 🙈

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Szymon Chmal @chmal.it · 06/08/2025

The Rozenite plugin family is growing, so I created a plugin directory! It includes both official plugins and community ones like rozenite-preview. Best part? You can add your own by opening a quick pull request on the Rozenite repo.

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Szymon Chmal @chmal.it · 04/08/2025

I scored a little discount just for you! Use promo code Chmal15 at checkout to get 15% off. Pretty sweet, right?

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Szymon Chmal @chmal.it · 04/08/2025

Just found out I'll be speaking at React Universe Conf! Rozenite's been out for a while, but in this talk, I'll dive deeper into how it works under the hood - how I hooked into DevTools without forking anything, and how you can build your own plugins too. Hope to see you there!

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Szymon Chmal @chmal.it · 04/08/2025

New week, new feature! Struggling to understand what's going on in your WebSocket connection? Fear not! Thanks to Rozenite, you'll soon be able to inspect WebSocket traffic and review each message one by one - whether it's text, binary, or JSON. Coming soon 🔥

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Szymon Chmal @chmal.it · 01/08/2025

Bronze trophy unlocked: 100 stars collected! It's not platinum (yet), but every legend starts somewhere 😉

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Szymon Chmal @chmal.it · 01/08/2025

Next stop: WebSocket interception - just like Chrome DevTools! You'll be able to see every message going in and out of the device. What do you think - super useful or not really? 🤔

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Szymon Chmal @chmal.it · 01/08/2025

Rozenite's Network Activity plugin got a major overhaul yesterday! The new UI and improved functionality make it much more convenient to use. You can now inspect request bodies and responses with an interactive JSON viewer 🚀

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Szymon Chmal @chmal.it · 30/07/2025

Rozenite is gaining traction - we've just crossed 50 stars on GitHub, and the number is steadily rising! It was included in the latest edition of the This Week in React newsletter, so if you slept through the release, it's high time you gave it a try and left a star while you're at it 🌟

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Szymon Chmal @chmal.it · 29/07/2025

Redux DevTools plugin for Rozenite is nearly complete. It offers basic debugging functionality, though without time travel or action dispatch capabilities. There's an upstream issue with the package that needs to be addressed first. github.com/callstackinc...

github.com

feat: introduce Redux Devtools plugin by V3RON · Pull Request #5 · callstackincubator/rozenite

This branch introduces a new Redux DevTools plugin for Rozenite, providing Redux state inspection and debugging capabilities within React Native DevTools. The plugin enables real-time state monitor...

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Szymon Chmal @chmal.it · 28/07/2025

Rozenite - a plugin framework for React Native DevTools - is now live in alpha! 🎉 What started as a hacky PoC is now something you can use in real projects. Still lots to come: better network monitor, Redux DevTools, Re.Pack support & more 💪

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Szymon Chmal @chmal.it · 16/07/2025

Big news: the React Native DevTools framework is dropping by the end of this month 🔥 The name? It's locked in and I'm so excited about it. It kicks off a whole family of tools designed to push React Native even further… but I'm not allowed to say anything else at this point 🙊

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Szymon Chmal @chmal.it · 14/07/2025

Just found out I'll be speaking at React Advanced! I'll be sharing my journey hacking on React Native Devtools + building a plugin framework from scratch. If you're curious how it all came together, tune in! The live stream is free - just register here: gitnation.com/badges/react...

gitnation.com

Check out my badge & claim your free React Advanced 2025 remote ticket!

Join 5k engineers worldwide at React Advanced 2025 and meet 50+ top speakers at Nov 27 - Dec 1, 2025

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Szymon Chmal @chmal.it · 08/05/2025

Built a file-based router for React Native - just for fun. It kinda works 😅 Learned a lot about Metro internals and found some cool low-level APIs along the way. Gave a talk about it! Check it out 👇 www.youtube.com/watch?v=oQjF...

youtube.com

I Built a File-Based Router for React Native by Szymon Chmal | React Universe Meetup, April 2025

YouTube video by Callstack Engineers

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Szymon Chmal @chmal.it · 28/04/2025

Might write a post (or a survival guide) about this RSC journey - from "how hard can it be?" to "send help." Would you be brave enough to read it? 😅

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Szymon Chmal @chmal.it · 28/04/2025

Short RSC update: ✅ 'use client' and 'use server' now become proxies. ✅ Server rendering is... holding together with duct tape. Now to bundle client components and pray React Native accepts them 🙃

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Szymon Chmal @chmal.it · 28/04/2025

The sun’s out, the birds are singing... and I’m buried in last-minute tweaks to the playground app for today’s JavaScript Performance webinar 😅 Still time to grab a spot if you missed the announcement! 👇 streamyard.com/watch/pnM9CY...

streamyard.com

Master JavaScript Performance in React Native: Part 2

This is Part 2 of our JavaScript optimization deep dive—a continuation of the webinar we hosted two weeks ago, based on Part 1 of Callstack’s Ultimate Guide to React Native Optimization. Hosted by: 🎙...

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Szymon Chmal @chmal.it · 25/04/2025

Missing memoization where it matters most? Let’s fix that. Join us for Part 2 of our React Native JavaScript perfomance deep dive - debounce, selectors, state shape & more. 📅 Apr 29 • 6PM CET 🎙️ @grabbou.com + me 🎟️ streamyard.com/watch/pnM9CY...

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Szymon Chmal @chmal.it · 11/04/2025

Your React Native application slowed down? We are here to help you! Join our walkthrough of Callstack's 2025 Optimization Guide (Part 1). You will have the opportunity to ask questions and have them answered for free, without any hidden catches. streamyard.com/watch/VW8Ufy...

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Szymon Chmal @chmal.it · 10/03/2025

I'm gathering examples of situations where developers might choose popular tools or patterns without fully considering if they fit the project's needs. For instance, using SSR for dynamic dashboards where it's not really necessary. Got any ideas for similar examples? 🧐

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Szymon Chmal @chmal.it · 10/03/2025

Another hype cycle is starting. People are asking if they should learn Lynx, as it's being called a "React Native killer." It’s probably too early to say, but some influencers are already fueling the buzz for views and likes.

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Szymon Chmal @chmal.it · 06/03/2025

Lynx: a hit or a miss? Let's find out together. This is going to be fun 🔥

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Szymon Chmal @chmal.it · 26/02/2025

Been exploring visual regression testing tools for React Native lately and it feels like the space is underdeveloped. 🤔 What features would your dream visual regression tool have to make you want to use it?

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Szymon Chmal @chmal.it · 17/02/2025

There is something wrong with IDB when it comes to streaming - the video is so distorted that it is unrecognizable. I tested it on two MacBooks and got the same result.

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Szymon Chmal @chmal.it · 17/02/2025

The case here is that I want to run a simulator in the background (without a UI) and stream the output to a web browser.

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Szymon Chmal @chmal.it · 16/02/2025

Anyone know how to capture and stream an iOS simulator’s screen? It used to be possible with simctl a few years ago. I tried idb, but the stream is full of artifacts 🤔

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Szymon Chmal @chmal.it · 13/02/2025

We are going live in a few minutes! Join us to learn more about the state of React! www.youtube.com/watch?v=bIa8... @lukasz.app @psyche.social

youtube.com

State of React 2024 Breakdown

YouTube video by Callstack Engineers

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Reposted by Szymon Chmal

lukasz.app @lukasz.app · 12/02/2025

We’re breaking down the "State of React 2024"! Hooks still cool, or did we go too far? Is React still king? 🤔 Join me, @psyche.social, and @chmal.it for some real talk! 📅 Tomorrow at 18:00 (GMT+1), 12:00 EST, 9:00 PST 📺 Watch: 🔴 YouTube: bit.ly/React2024Survey 🔴 Twitch: twitch.tv/callstack_live

bit.ly

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Szymon Chmal @chmal.it · 11/02/2025

Introducing metro-minify-swc 🚀 It’s an experimental package that replaces Terser with SWC for blazing-fast code minification. Use with caution and share your feedback ⚡️ github.com/V3RON/metro-...

github.com

GitHub - V3RON/metro-minify-swc: A high-performance drop-in replacement for Metro bundler's minifier using SWC ⚡️

A high-performance drop-in replacement for Metro bundler's minifier using SWC ⚡️ - V3RON/metro-minify-swc

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Szymon Chmal @chmal.it · 10/02/2025

Just switched from Terser to SWC in Metro. Saw nearly a 30% improvement in build time and even a slight reduction in size. Worth it 🔥

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Szymon Chmal @chmal.it · 09/02/2025

Sunday coding vibes: Aurora can now peek into your bundle and spot duplicated dependencies. Pretty neat!

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Szymon Chmal @chmal.it · 06/02/2025

Meet Aurora - my personal sidekick for making the best of React Native projects 🌟

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Szymon Chmal @chmal.it · 06/02/2025

Why did no one mention Synology NASes are this loud? My router is near my bedroom, and so is the NAS. Some nights, it’s noisy enough to pull me out of sleep ☹️

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Szymon Chmal @chmal.it · 05/02/2025

I just signed up for three runs this year: a 5km, a 10km, and, wait for it, a half marathon. I’m almost certain I’ll be questioning all my life choices the moment the starting whistle blows, lol

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Szymon Chmal @chmal.it · 02/02/2025

Struggling to inspect your Metro bundle in a bare React Native project? 🤔 I created a simple library that lets you use Expo Atlas without the full Expo setup! github.com/V3RON/expo-a... If it helps, consider leaving a star! 🌟

github.com

GitHub - V3RON/expo-atlas-without-expo: Supercharge your vanilla React Native apps with Expo Atlas metrics

Supercharge your vanilla React Native apps with Expo Atlas metrics - V3RON/expo-atlas-without-expo

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Szymon Chmal @chmal.it · 28/01/2025

Did you know? Shared Workers let multiple tabs of the same website share a single Web Worker. Perfect for WebSocket apps - one connection, no matter how many tabs are open. Read more here: javascript.plainenglish.io/sharing-webs...

javascript.plainenglish.io

Sharing WebSocket Connections between Browser Tabs and Windows

WebSocket connections are like special communication channels that allow web browsers and servers to talk to each other in real-time…

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