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structuredClone loses own __proto__ data properties

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
58/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
javascript, react-native
Domain
mobile

Research direction

The entry point is React Native's structuredClone polyfill; start by reproducing the issue with objects and arrays that own enumerable proto data properties. Done means the clone retains its normal Object or Array prototype and has a deeply cloned own property matching native structuredClone behavior.

Written by the indexing model from the issue text.

Description

Needs: Author Feedback Needs: Repro
Description

The React Native structuredClone polyfill copies enumerable properties with ordinary assignment. For an own __proto__ data property on an object or array, assignment invokes the inherited prototype setter: the clone's prototype is replaced and no own property is created.

Expected behavior

__proto__ should be cloned as an ordinary own enumerable/writable/configurable data property with a deeply cloned value, while the clone keeps its normal Object or Array prototype. Native structuredClone follows this behavior.

React Native Version

0.87.1 and current main

Affected Platforms

JavaScript runtime - All

Dominant language
C++
Stars
127k
Forks
25.3k
PR merge metrics
No merged PRs in 30d

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