MySlider.js

currentIndex = 0;
  scrollNext = () => {
    if (this.currentIndex !== this.state.data.length - 1) {
      this.flatListRef.scrollToIndex({
        index: this.currentIndex + 1,
        animated: true,
      });
    }
  };
  scrollPrevious = () => {
    if (this.currentIndex !== 0) {
      this.flatListRef.scrollToIndex({
        index: this.currentIndex - 1,
        animated: true,
      });
    }
  };
  onViewableItemsChanged = ({viewableItems, changed}) => {
    if (changed[0].isViewable) {
      this.currentIndex = changed[0].index;
    }
  };