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docs: clarify FlatList extraData prop and PureComponent behavior (fixes #5216) - #5282
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Simek merged 1 commit intoOct 19, 2026
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I'd looked into #5216 earlier, so I checked this against the source: It also corrects something in my comment on the issue: I tied the stable- This is from reading the source, not a device run. |
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Thanks for checking this against the source and for the clarification! Glad
the updated wording is accurate.
…On Fri, Oct 16, 2026 at 7:34 PM Pranta Dutta ***@***.***> wrote:
*theprantadutta* left a comment (react/react-native-website#5282)
<#5282 (comment)>
I'd looked into #5216
<#5216> earlier, so I
checked this against the source: FlatList extends React.PureComponent (
FlatList.js
<https://github.com/react/react-native/blob/9ae68b57788f8124698d9c7444518f6b1198789b/packages/react-native/Libraries/Lists/FlatList.js#L310>).
So with a stable renderItem and unchanged data, the shallow prop check
skips the re-render entirely, and extraData is what gets it through. The
wording here is right.
It also corrects something in my comment on the issue: I tied the stable-
renderItem case to strictMode, which was too narrow. strictMode just adds
a second memoization layer on top, and the PureComponent check applies
either way.
This is from reading the source, not a device run.
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Thanks @supunyasanthaofficial for updating the docs, and @theprantadutta for confirmation and verification! 👍
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Summary
Fixes #5216.
Clarifies how
extraDataworks in the selectableFlatListexample indocs/flatlist.md. The change is also applied to the versioned docs from0.77through0.87.Changes
extraDatatellsFlatListwhen it needs to account for changes in data outside itsdataprop.FlatListuses shallow prop comparison, soextraDatais important whenrenderItemdoesn't change its reference but depends on external state.Test Plan
npx eslint docs/flatlist.mdwith no errors.0.77through0.87.