Callstack’s recap of App.js and Chain React 2023

Łukasz and Szymon did not attend Chain React, so Kuba shared colleagues’ impressions of its lineup, which included speakers from Meta, Microsoft, Expensify, and Formidable. Callstack colleagues Michał Piskorz and Basia attended, and Michał gave a talk. The hosts hoped the recordings would be posted so they could watch and review them.

Szymon described App.js, held May 10–12 in Kraków, as his first large conference and praised the community and opportunities to meet people. The recap highlights Expo Application Services features including QR-code previews for pull requests and builds triggered by labels. It also covers Skia updates, such as backdrop filters for blurring native views, and Expo Router v2 features including automatic deep links, typed routes, and async screen loading.

The hosts recap talks on 3D graphics with Expo GL, Reanimated, and Gesture Handler, plus a live demonstration of React Native running on a Raspberry Pi with Linux. They also discuss React Native for macOS and Messenger’s reported improvements in performance and time to interactive after moving from Electron. Nicola Corti’s review covered React Native releases and an experimental way to run unmigrated Paper components inside an app using the New Architecture.

Alex’s Metro talk covered symlink support, a larger developer experience team at Meta, and planned lazy bundling, while SWC support was still in research. Expensify’s Horace described paying contributors for confirmed bugs and merged fixes, including one reported payment above $60,000, and said community work helped with migrations such as class components to functions and JavaScript to TypeScript. Other talks covered dark-mode implementation, Rust in React Native, Flashlight’s mobile performance testing, and experimental video creation with Remotion.