Unexpected scroll behaviors when using FlatList
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Description
Description
Content teleports to right when over-scrolling, if the content is less.
What I am trying to do? 🤔
Two FlatList components are nested inside a ScrollView for a custom component to emulate a grid like structure.
Example:
_________
|
|
[] [] [] | [] []
[] [] [] | [] []
[] [] [] | [] []
[] [] [] | []
|
|
▔▔▔▔▔
[] represent grid items and | represents edge of the screen. The items are accessed by scrolling horizontally.
How am I doing this? ❓
export function HorizontalRowList({
rows, data, renderItem,
bounces = false,
itemSeparatorComponent,
style, columnStyle
}) {
const columns = divideArrayIntoChunks(rows, data);
return (
<ScrollView style={{ ...style, overflow: "hidden" }}
showsVerticalScrollIndicator={false}
nestedScrollEnabled={true}
alwaysBounceHorizontal={bounces}
bounces={bounces}>
<FlatList data={columns}
style={{ borderColor: "blue", borderWidth: 1, overflow: "hidden" }}
ItemSeparatorComponent={itemSeparatorComponent}
nestedScrollEnabled={true}
legacyImplementation={false}
initialNumToRender={columns.length}
horizontal={true}
alwaysBounceHorizontal={bounces}
bounces={bounces}
renderItem={(column) => {
return <FlatList data={column.item}
style={columnStyle}
ItemSeparatorComponent={itemSeparatorComponent}
legacyImplementation={false}
bounces={bounces}
renderItem={({ item }) => {
return renderItem(item);
}} />
}} />
</ScrollView >
)
}
function divideArrayIntoChunks(chunkSize, array) {
const chuckedArray = []
for (let i = 0; i < array.length; i += chunkSize) {
chuckedArray.push(array.slice(i, i + chunkSize))
}
return chuckedArray;
}
ScrollView to disable individual vertical scroll bars for the columns when the component has less space.
The first FlatList to enable horizontal behavior of grid
The second FlatList component are columns. The component can be given used to render list of varying sizes.
When the bug occurs? 🪲
The bug happens when data is less and rows to render are more. This causes the array to be chunked in the following way:
[] [] |
[] [] |
[] [] |
[] |
Steps to reproduce
- Create a new project
- Add the code for
HorizontalRowListcomponent given in the description - Import and add the component in App.js
- Create a random list of strings or any other object
- Pass this list to data attribute of
HorizontalRowList - Set the row attribute in such a way that there is considerable space to the right of the
HorizontalRowList - Try scrolling
HorizontalRowListand observe the behavior
React Native Version
0.73.6
Affected Platforms
Runtime - Android
Output of npx react-native info
System:
OS: Windows 11 10.0.22631
CPU: (8) x64 11th Gen Intel(R) Core(TM) i5-1155G7 @ 2.50GHz
Memory: 5.68 GB / 15.78 GB
Binaries:
Node:
version: 21.0.0
path: C:\Program Files\nodejs\node.EXE
Yarn: Not Found
npm:
version: 10.4.0
path: C:\Program Files\nodejs\npm.CMD
Watchman: Not Found
SDKs:
Android SDK: Not Found
Windows SDK: Not Found
IDEs:
Android Studio: Not Found
Visual Studio:
- 17.8.34408.163 (Visual Studio Community 2022)
Languages:
Java: Not Found
Ruby: Not Found
npmPackages:
"@react-native-community/cli": Not Found
react:
installed: 18.2.0
wanted: 18.2.0
react-native:
installed: 0.73.6
wanted: ^0.73.6
react-native-windows: Not Found
npmGlobalPackages:
"*react-native*": Not Found
Android:
hermesEnabled: Not found
newArchEnabled: Not found
iOS:
hermesEnabled: Not found
newArchEnabled: Not found
Stacktrace or Logs
No Errors
Reproducer
Please check this snack
https://staging-snack.expo.dev/kawPQ53xi5xNUpxnPKYfB
Screenshots and Videos
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
Start with the HorizontalRowList example in App.js and the linked Snack, using React Native 0.73.6 on Android. Reproduce the nested ScrollView and FlatList case where data is shorter than the requested rows, then trace the scrolling behavior. Done means the content no longer teleports horizontally when over-scrolling.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- javascript, react-native
- Domain
- mobile
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100