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structuredClone coerces boxed primitives and flips false Boolean

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#58,226 1 comment 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
68/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Active
Tech stack
javascript, react-native
Domain
mobile

Research direction

Start at the React Native structuredClone polyfill entry point and reproduce the behavior with boxed Number, String, Boolean, and Date values. Check that cloning reads the internal primitive without running user coercion hooks, preserves false Boolean values, and creates distinct wrappers; compare the result with native structuredClone.

Written by the indexing model from the issue text.

Description

Needs: Author Feedback Needs: Repro
Description

The React Native structuredClone polyfill reconstructs Number, String, Boolean, and Date wrappers by passing the source object to a constructor. Number/String cloning invokes user coercion hooks, and new Boolean(new Boolean(false)) uses object truthiness and silently changes the internal value to true.

Expected behavior

Cloning should read each wrapper's internal primitive through the built-in valueOf intrinsic, create a distinct wrapper with the same value, and never execute user coercion. 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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