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wire 2026-05-09
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JEST FIXES CJS-FROM-ESM INTEROP, REACT NATIVE STABILIZES VIRTUALIZEDLIST

By RepoJournal · Filed · About Meta · Composed from the cited sources · methodology

SimenB ahnpnl
2 people shipped this
SimenB @SimenB 2 cited ahnpnl @ahnpnl 1 cited

Jest shipped three critical fixes for CommonJS-to-ESM module interop that align behavior with Node.js, while React Native re-enabled a flaky VirtualizedList test and fixed out-of-order events on Android Fabric.

Jest's runtime layer was leaking `__esModule` unwrapping into CJS imports of ESM modules, breaking interop expectations [1]. The team also fixed function module.exports handling for named exports [2] and added long-overdue support for custom runner configuration via tuple format [7]—reporters got this years ago, runners finally caught up. On the React Native side, VirtualizedList's "retains batch render region" test was unstable under React 19's timer semantics and now passes reliably [3]. Android Fabric developers will want the out-of-order event fix [4], which addresses buffering behavior when EventEmitterWrapper hasn't mounted yet. The 0.86.0-rc.0 changelog is live [5] and Hermes bumped to 250829098.0.13 [6], bringing the latest compiler optimizations.

Action items

References

  1. [1] fix(jest-runtime): align CJS-from-ESM default with Node, drop `__esModule` unwrapping ↗ facebook/jest
  2. [2] fix(jest-runtime): handle function module.exports for CJS-from-ESM named exports ↗ facebook/jest
  3. [3] Re-enabled VirtualizedList "retains batch render region when an item is appended" test (#56653) ↗ facebook/react-native
  4. [4] Fix Fabric out-of-order event delivery on Android ↗ facebook/react-native
  5. [5] Add changelog for v0.86.0-rc.0 (#56711) ↗ facebook/react-native
  6. [6] Bump Hermes V1 to latest stable 250829098.0.13 (#56728) ↗ facebook/react-native
  7. [7] feat: allow custom runner configuration options (tuple format) ↗ facebook/jest

$ ls meta/reviews/ # the step-back reads

the week in review React 19.3 ships View Transitions, RN 0.88-rc breaks Touchable the month in review React, React Native, and Jest harden the stack
Full archive → Weekly reviews →

Quick answers

What shipped in Meta on May 9, 2026?
Jest shipped three critical fixes for CommonJS-to-ESM module interop that align behavior with Node.js, while React Native re-enabled a flaky VirtualizedList test and fixed out-of-order events on Android Fabric. In total, 11 commits, 4 pull requests, and 2 releases landed.
Who contributed to Meta on May 9, 2026?
2 developers shipped this update, including SimenB and ahnpnl.
What were the notable Meta updates?
fix(jest-runtime): align CJS-from-ESM default with Node, drop `__esModule` unwrapping, fix(jest-runtime): handle function module.exports for CJS-from-ESM named exports, and Re-enabled VirtualizedList "retains batch render region when an item is appended" test (#56653).
♥

$ log Meta --recent

React Native strips dead config, React compiler fixes exponent folding 21 shipped React Native's generated SwiftPM manifests inherit the app's iOS floor, and SectionList scrolls to the right row 30 shipped React stops emulating bubbling for toggle events, fixes Fragment compareDocumentPosition 9 shipped React Native's Babel preset stops dropping Platform.select side effects 6 shipped

$ log --all # elsewhere on the wire

Alignment & Post-training GSM8K scoring parses answers as exact decimals AI Red Teaming PyRIT closes a judge-spoofing hole, promptfoo accepts Langfuse v6

$ ls showcases/

Safety Evals AI Red Teaming Agent Security Interpretability Alignment & Post-training

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