block3.js

viewabilityConfig = {
    waitForInteraction: true,
    viewAreaCoveragePercentThreshold: 95,
    itemVisiblePercentThreshold: 75
  }

  onViewableItemsChanged = ({viewableItems, changed}) => {
    console.log("Visible items are", viewableItems);
    console.log("Changed in this iteration", changed);
  };

  render() {
    return (
      <FlatList
        style={{
          paddingTop: 60
        }}
        viewabilityConfig={this.viewabilityConfig}
        onViewableItemsChanged={this.onViewableItemsChanged}
        data={this._items}
        renderItem={this._renderItem}
        keyExtractor={item => item.id}
      />
    )
  }