When I click any menu item, it scrolls to the correct section. How to highlight the correct menu when I scroll to other section, like this?
class List extends Component {
constructor(props) {
super(props);
this.arr = [];
}
onPressFilter(val) {
this.setState({ selectedTab: val });
let dynamicIndex = categoryArr.indexOf(val);
this.refs._scrollView.scrollTo({
x: 0,
y: this.arr[dynamicIndex] - 55,
animated: true,
});
}
render(){
return (
<ScrollView>
<ScrollView ref='_scrollView'>
{{this.props.data.map((val, index) =>
<TouchableOpacity
style={[styles.filterItem, (selectedTab === val) && {backgroundColor: themeColor}]}
onPress={this.onPressFilter.bind(this, val)} key={index}>
<Text style={[styles.filterText, (selectedTab === val) && {color: '#fff'}]}>{val.toUpperCase()}</Text>
</TouchableOpacity>)}}
</ScrollView>
{CategoryList.map((el, key) => (<View key={key}
onLayout={event => {
const layout = event.nativeEvent.layout;
this.arr[key] = layout.y;
}}>
<View style={{paddingHorizontal: 20, paddingVertical: 10}}>
<H2>{el.toUpperCase()}</H2>
</View>
<FlatList
data={DATA.filter((a, i) => a.category.name === el)}
renderItem={({ item }) => <Item item={item} data={DATA} />}
keyExtractor={item => item.id}
/>
</View>))}
</ScrollView>
)
}
}
