Dynamic item height causes items to overlap during fast scroll
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- Dominant language
- TypeScript
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Description
Description
When using FlashList with dynamic item heights, quickly scrolling up/down causes content to jump, collapse, and overlap each other.
Steps to Reproduce
- Render a FlashList with dynamic item heights (items have varying/unpredictable heights)
- Scroll quickly up and down
Expected Behavior
Items maintain their correct heights and positions while scrolling.
Actual Behavior
Items jump, collapse, and overlap each other during fast scroll due to incorrect height estimations for dynamic items.
Platform
- iOS
- Android
FlashList Version
2.3.0
https://github.com/user-attachments/assets/a9bbb356-4942-4773-b9d0-3ec0c8e3cde9
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
No files, tests, or entry points are named in the issue. Start by reproducing the fast-scroll behavior with dynamic-height items on iOS and Android, then trace the height estimation and layout path. Done means items retain their correct heights and positions without jumping, collapsing, or overlapping.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- react-native, typescript
- Domain
- mobile
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 35/100