Who contributed to Meta on August 18, 2026?

4 developers shipped this update, including Kamil Paradowski, Christoph Purrer, Gijs Weterings, and SimenB.

What were the notable Meta updates?

RCTArrayBuffer zero-copy class for ObjC TM (#57879), JArrayBuffer zero-copy class for Java TM (#57897), and Enforce the ArrayBuffer borrow contract for Java TurboModules (#57982).

React Native kills the ArrayBuffer copy tax

By RepoJournal · Filed 06:58 UTC on August 18, 2026 · About Meta

4 people shipped this

SimenB @SimenB 3 cited

Kamil Paradowski @paradowstack 2 cited

Christoph Purrer @christophpurrer 1 cited

Gijs Weterings @GijsWeterings 1 cited

React Native just made TurboModule ArrayBuffer crossing zero-copy on both iOS and Android, and the borrow contract is now enforced in Java.

React Native shipped a pair of zero-copy classes that eliminate the per-crossing `ArrayBuffer` copy on iOS `NSData` and Android `ByteBuffer` [1][2]. The new `RCTArrayBuffer` carries an `isOwningBytes` flag, and the follow-up Java hardening [3] enforces the borrow contract so borrowed JS-heap bytes can't outlive the call that lent them. "Follow-up hardening for the Android `ArrayBuffer` TurboModule type" [3] is exactly what this is: three distinct problems fixed, including a synchronous method handing the module a `ByteBuffer` aliasing JS memory. Work is also in progress to run the ReactAndroid JNI gtests as instrumentation tests [4], since the current host-binary setup can't even load without `/system/bin/linker64`. Over in Jest, `jest-haste-map` gets three correctness fixes [5][6][7]: duplicated mock names survive a file deletion in watch mode, locked files on Windows (like `git maintenance` touching `.git/index.lock`) no longer abort the crawl, and the cache key now separates its 11 concatenated fields. With 12 commits and 3 PRs across both repos, the focus is clearly on shaving cross-language overhead and hardening the edge cases that only manifest in production.

Action items

→ Upgrade React Native to a nightly with #57879 and #57982 to get zero-copy ArrayBuffer and the borrow contract enforcement facebook/react-native [plan]
→ Update Jest to include #16360 fix if you rely on duplicated mock names in watch mode facebook/jest [plan]
→ Test Jest on Windows after #16358 to confirm locked-file tolerance works with your tooling facebook/jest [monitor]

References

[1] RCTArrayBuffer zero-copy class for ObjC TM (#57879) facebook/react-native
[2] JArrayBuffer zero-copy class for Java TM (#57897) facebook/react-native
[3] Enforce the ArrayBuffer borrow contract for Java TurboModules (#57982) facebook/react-native
[4] Run the ReactAndroid JNI gtests as instrumentation tests (#57976) facebook/react-native
[5] fix(jest-haste-map): keep a duplicated mock name alive when its file goes ↗ facebook/jest
[6] fix(jest-haste-map): tolerate a locked file while indexing on Windows ↗ facebook/jest
[7] fix(jest-haste-map): tighten the cache key and the watched-extension match ↗ facebook/jest

Quick answers

What shipped in Meta on August 18, 2026?: React Native just made TurboModule ArrayBuffer crossing zero-copy on both iOS and Android, and the borrow contract is now enforced in Java. In total, 12 commits and 3 pull requests landed.
Who contributed to Meta on August 18, 2026?: 4 developers shipped this update, including Kamil Paradowski, Christoph Purrer, Gijs Weterings, and SimenB.
What were the notable Meta updates?: RCTArrayBuffer zero-copy class for ObjC TM (#57879), JArrayBuffer zero-copy class for Java TM (#57897), and Enforce the ArrayBuffer borrow contract for Java TurboModules (#57982).

Jest's resolver gets a major speedup and Node-compatible module handling

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javascript 34 shipped

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