React Native FlatList with inverted option enabled - react-native

Question

I have a FlatList as shown below:
<FlatList
inverted
data={messages}
keyExtractor={this._keyExtractor}
renderItem={({ item }) => (
<Text style={styles.item}>{item}</Text>
)}
onEndReached={this.handleLoadMore}
onEndReachedThreshold={30}
/>
But here the OnEndReached method does not gets called when I reach the top of the flatlist.
Please help

Answer 1

OnEndReachedThreshold must be a number between 0 and 1. Since you are inverting your flatlist, onEndReachedThreshold would be the distance the user is from the top of the list [in percents]. Therefore a value of 0.5 would trigger the OnEndReached function when the user has scrolled through 50% of the viewable list.
To trigger the function at 50% your code should read something like this:
<FlatList
inverted
data={messages}
keyExtractor={this._keyExtractor}
renderItem={({ item }) => (
<Text style={styles.item}>{item}</Text>
)}
onEndReached={this.handleLoadMore}
onEndReachedThreshold={0.5}
/>

Answer 2

All I could figure out was using of onScroll (performance beware) in here: https://snack.expo.io/#zvona/inverted-list-onbeginreached
The actual function looks like this:
checkIfBeginningReached = ({ nativeEvent }) => {
const { layoutMeasurement, contentOffset } = nativeEvent;
const currentPos = layoutMeasurement.height + contentOffset.y;
const listLength = ITEM_HEIGHT * this.state.items.length;
const reactThreshold = listLength - (ITEM_HEIGHT * THRESHOLD);
if (currentPos >= reactThreshold) {
this.fetchMoreItems(this.state.items.length);
}
}
On that, we pick up necessary info from nativeEvent (which kind of holds everything relevant). Then we just calculate the current position in pixels, length of whole list content in pixels and then threshold point.
In all, this particular solution requires two things:
1) list has fixed and same size of elements
2) list is not multi-column.
All the other functionality in the demo is just faking / mimicking one use case (of fetching 50 more items from server with 500ms delay). But I'll improve my answer if possible. But this should get you started.

Answer 3

My solution is here:
isCloseToBottom = ({layoutMeasurement, contentOffset, contentSize}) => {
const paddingToBottom = 1
return layoutMeasurement.height + contentOffset.y >=
contentSize.height - paddingToBottom}

Answer 4

just set onEndReachedThreshold={0.1} or onEndReachedThreshold={0.2}