React Native - how to scroll a ScrollView to a given location after navigation from another screen
Solution 1
I read that you can pass in parameters when using the StackNavigator like so: but I don't know how to read out that parameter in my Items screen.
That is achieved by accessing this.props.navigation.state.params
inside your child component.
I think the best time to call scrollTo
on your scrollview reference is when it first gets assigned. You're already giving it a reference and running a callback function - I would just tweak it so that it also calls scrollTo
at the same time:
export default class Items extends React.Component {
render(){
let scrollItems = [] //Somecode that generates and array of items
const {id} = this.props.navigation.state.params;
return (
<View>
<View style={styles.scrollViewContainer}>
<ScrollView
horizontal
pagingEnabled
ref={(ref) => {
this.myScroll = ref
this.myScroll.scrollTo() // !!
}>
{scrollItems}
</ScrollView>
</View>
</View>
)
}
}
And this is why I use FlatLists or SectionLists (which inherit from VirtualizedList) instead of ScrollViews. VirtualizedList
has a scrollToIndex function which is much more intuitive. ScrollView's scrollTo expects x and y parameters meaning that you would have to calculate the exact spot to scroll to - multiplying width of each scroll item by the index of the item you're scrolling to. And if there is padding involved for each item it becomes more of a pain.
Solution 2
Yes, this is possible by utilising the scrollTo
method - see the docs. You can call this method in componentDidMount
. You just need a ref to call it like: this.myScroll.scrollTo(...)
. Note that if you have an array of items which are all of the same type, you should use FlatList
instead.
Solution 3
Here is an example of scroll to the props with id.
import React, { Component } from 'react';
import { StyleSheet, Text, View, ScrollView, TouchableOpacity, Dimensions, Alert, findNodeHandle, Image } from 'react-native';
class MyCustomScrollToElement extends Component {
constructor(props) {
super(props)
this.state = {
}
this._nodes = new Map();
}
componentDidMount() {
const data = ['First Element', 'Second Element', 'Third Element', 'Fourth Element', 'Fifth Element' ];
data.filter((el, idx) => {
if(el===this.props.id){
this.scrollToElement(idx);
}
})
}
scrollToElement =(indexOf)=>{
const node = this._nodes.get(indexOf);
const position = findNodeHandle(node);
this.myScroll.scrollTo({ x: 0, y: position, animated: true });
}
render(){
const data = ['First Element', 'Second Element', 'Third Element', 'Fourth Element', 'Fifth Element' ];
return (
<View style={styles.container}>
<ScrollView ref={(ref) => this.myScroll = ref} style={[styles.container, {flex:0.9}]} keyboardShouldPersistTaps={'handled'}>
<View style={styles.container}>
{data.map((elm, idx) => <View ref={ref => this._nodes.set(idx, ref)} style={{styles.element}}><Text>{elm}</Text></View>)}
</View>
</ScrollView>
</View>
);
}
const styles = StyleSheet.create({
container: {
flexGrow: 1,
backgroundColor:"#d7eff9"
},
element:{
width: 200,
height: 200,
backgroundColor: 'red'
}
});
export default MyCustomScrollToElement;
Related videos on Youtube

davidx1
Updated on April 28, 2022Comments
-
davidx1 17 days
Is it possible to tell a ScrollView to scroll to a specific position when we just navigated to the current screen via StackNavigator?
I have two screens; Menu and Items. The Menu is a list of Buttons, one for each item. The Items screen contain a Carousel built using ScrollView with the picture and detailed description of each Item.
When I click on a button in the Menu screen, I want to navigate to the Items screen, and automatically scroll to the Item that the button represent.
I read that you can pass in parameters when using the StackNavigator like so: but I don't know how to read out that parameter in my Items screen.
navigate('Items', { id: '1' })
So is this something that is possible in React Native and how do I do it? Or perhaps I'm using the wrong navigator?
Here's a dumbed down version of my two screens:
App.js:
const SimpleApp = StackNavigator({ Menu: { screen: MenuScreen}, Items: { screen: ItemScreen } } ); export default class App extends React.Component { render() { return <SimpleApp />; } }
Menu.js
export default class Menu extends React.Component { constructor(props){ super(props) this.seeDetail = this.seeDetail.bind(this) } seeDetail(){ const { navigate } = this.props.navigation; navigate('Items') } render(){ <Button onPress={this.seeDetail} title='1'/> <Button onPress={this.seeDetail} title='2'/> } }
Items.js
export default class Items extends React.Component { render(){ let scrollItems = [] //Somecode that generates and array of items return ( <View> <View style={styles.scrollViewContainer}> <ScrollView horizontal pagingEnabled ref={(ref) => this.myScroll = ref}> {scrollItems} </ScrollView> </View> </View> ) } }
P.S I am specifically targeting Android at the moment, but ideally there could be a cross-platform solution.
-
davidx1 over 4 yearsBut I need to know which Item was selected to know where to scroll to. How do I let my Items screen know which item was selected in the previous Menu screen?
-
vonovak over 4 yearsideally you should know the index of the item that was selected and send it as a prop to the
items screen
. then you can use thescrollToIndex
method, provided your items are all the same height. -
davidx1 over 4 yearsHello, yes I know the index of the item that was selected. What I'm not sure is how to pass the index as a prop from one screen to another via StackNavigator, or any other navigators
-
KAUSHIK PARMAR about 1 yearIt returns _nativeTag property instead of actual position. This does not solve the problem.