Starting with React Native 0.69, each React Native release comes with a compatible Hermes version, avoiding separate version matching and possible ABI incompatibilities. Building Hermes added time to the release process, so the team backported build performance fixes. The hosts also covered React Native Paper v5’s release candidate and its Material You support, plus stability fixes in React 18.2, including a Safari microtask issue triggered by adding certain iframes.
React Native News & App.js Conf
Speakers
Callstack hosts Michał and Abi, a JavaScript and TypeScript developer, discuss React Native and React news, then compare their in-person and livestream perspectives on App.js Conf in Kraków.
The hosts discuss Joel Arvidsson’s early React Native esbuild project as a potential Metro replacement. Joel reported bundles building 10 to 50 times faster and apps up to 21% smaller through tree shaking. They also describe Reassure, a Callstack project for regression testing React components, initially aimed at React Native and expected to support React for web.
Michał describes the two-day Kraków conference as an expo-first event, praising its former railroad depot venue, production setup, and workshops. Abi, who watched remotely, says the event felt professionally produced and appreciated the talks, breaks, and stream editing. They note that virtual attendees could see interviews during breaks that Michał missed while speaking and meeting people in person.
Abi highlights Charlie Cheever’s Expo keynote on EAS Update and EAS Metadata, and Evan Bacon’s presentation about Expo. Michał mentions Thomas Appet’s Sweet API for synchronous native modules using Swift and Kotlin DSLs, Catalin’s Reanimated animations talk, Nicola Corti’s overview of the new React Native architecture, and Kudo’s V8 experiments comparing runtimes with Hermes and JSC.
Takeaways
- Bundling a compatible Hermes version with React Native can remove manual version matching and reduce ABI mismatch risk.
- Measure build time when adopting new architecture features, since compiling Hermes and Reanimated from source can add substantial time.
- Consider esbuild’s reported speed and bundle size gains as early project results, and check compatibility with your own app before switching bundlers.
- Regression testing React components can help catch performance regressions as a codebase evolves.
- Plan conference participation around the format: in-person attendees can use breaks to network, while livestream viewers may catch streamed interviews.
Mentioned in this talk
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What was claimed 6
- featureReact Native Paper: version 5 release candidate implements Material Youversion 5 release candidate implements Material You
“React Native Paper was expected to have it in version 1.0”
0:34inReact Native Paper Supports Material Design 2.0YouTube Verified2 sources· Talk
- featureReact Native 0.69: built alongside a compatible Hermes versionbuilt alongside a compatible Hermes version
“Starting with React Native 0.69, every version of React Native is built alongside a Hermes version.”
YouTube Unverified1 source· Talk
- uses
Hermes Agent uses JSI“Hermes and React Native are built with and use JSI to power their features.”
YouTube Unverified1 source· Talk
- featureReassure: Regression testing for React components, initially in React Native
“It aims to solve regression testing of their React components.”
YouTube Unverified1 source· Talk
- role atSoftware Mansion is organizer at App.js Conf
“Great work to Software Mansion for organizing this conference.”
YouTube Unverified1 source· Talk
- featureExpo: EAS Update and EAS Metadata were discussed in its keynote
“The keynote address by Charlie Cheever from Expo, touching on EAS Update and EAS Metadata.”
YouTube Unverified1 source· Talk
