javascript - Add a separator every 3 item in flatlist - React Native - Stack Overflow

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How can I add a separator for every 3 items in flatlist? I can just add a separator after every 1 item. I did not find a prop for that. Here are my codes:

import React from 'react';
import { SafeAreaView, View, FlatList, StyleSheet, Text} from 'react-native';

const DATA = [
    {
        id: 1,
        title: 'Item 1',
    },

    {
        id: 2,
        title: 'Item 2',
    },
    {
        id: 3,
        title: 'Item 3',
    },
    {
        id: 4,
        title: ' Item 4',
    },
    {
        id: 5,
        title: 'Item 5',
    },
    {
        id: 6,
        title: 'Item 6',
    },
    {
        id: 7,
        title: 'Item 7',
    },
];


const App = () => {

    const renderItem = ({ item }) => (
        <View style={styles.item}>
            <Text style={styles.title}>{item.title}</Text>
        </View>
    );

    const seperator = () => {
        return (
            <View style={styles.seperator} />
        )
    }

    return (
        <SafeAreaView style={styles.container}>
            <FlatList
                data={DATA}
                renderItem={renderItem}
                keyExtractor={(items) => items.id}
                ItemSeparatorComponent={seperator}
            />
        </SafeAreaView>
    );
}

const styles = StyleSheet.create({
    container: {
        flex: 1,
    },
    item: {
        backgroundColor: '#f9c2ff',
        padding: 10,
        marginVertical: 8,
        marginHorizontal: 16,
    },
    title: {
        fontSize: 32,
    },
    seperator: {
        width: 300,
        height: 10,
        backgroundColor: 'red'
    }
});

export default App;

How can I add a separator for every 3 items in flatlist? I can just add a separator after every 1 item. I did not find a prop for that. Here are my codes:

import React from 'react';
import { SafeAreaView, View, FlatList, StyleSheet, Text} from 'react-native';

const DATA = [
    {
        id: 1,
        title: 'Item 1',
    },

    {
        id: 2,
        title: 'Item 2',
    },
    {
        id: 3,
        title: 'Item 3',
    },
    {
        id: 4,
        title: ' Item 4',
    },
    {
        id: 5,
        title: 'Item 5',
    },
    {
        id: 6,
        title: 'Item 6',
    },
    {
        id: 7,
        title: 'Item 7',
    },
];


const App = () => {

    const renderItem = ({ item }) => (
        <View style={styles.item}>
            <Text style={styles.title}>{item.title}</Text>
        </View>
    );

    const seperator = () => {
        return (
            <View style={styles.seperator} />
        )
    }

    return (
        <SafeAreaView style={styles.container}>
            <FlatList
                data={DATA}
                renderItem={renderItem}
                keyExtractor={(items) => items.id}
                ItemSeparatorComponent={seperator}
            />
        </SafeAreaView>
    );
}

const styles = StyleSheet.create({
    container: {
        flex: 1,
    },
    item: {
        backgroundColor: '#f9c2ff',
        padding: 10,
        marginVertical: 8,
        marginHorizontal: 16,
    },
    title: {
        fontSize: 32,
    },
    seperator: {
        width: 300,
        height: 10,
        backgroundColor: 'red'
    }
});

export default App;

My app looks likes:

But I want to make that:

How can I add a separator for every 3 items in flatlist? I can just add a separator after every 1 item. I did not find a prop for that.

• javascript
• react-native
• react-native-flatlist
• separator
• flatlist

Share Improve this question Follow asked Sep 10, 2021 at 0:00 SoFSoF 78711 gold badge1414 silver badges3333 bronze badges 2

• Haven't tested but can try this logic. In the Item constant -- You check whether the item is the third (item.id %3 === 0)and then call the separator function in the renderItem function itself. – Shubham Periwal Commented Sep 10, 2021 at 0:35
• Got Fizz Buzz?? – Dexygen Commented Sep 11, 2021 at 1:27

Add a ment  | 

2 Answers 2

Sorted by: Reset to default 5

In case your data items do not have an id or a property that can easily distinguish two items, consider using a counter to keep track of how many times your separator function was called.

To do so, useRef hook can be used, as:

useRef returns a mutable ref object whose .current property is initialized to the passed argument

And since this hook is mutable, it's possible to count how many times the function is called, thus tracking how many items are skipped.

import { useState, useRef } from 'react'; 

const App = () => { 
    let [skipItems,] = useState(3); // change to the number of items to skip
    let count = useRef(0);

    const separator = (e) => {
          count.current += 1;
          return (
            (count.current % skipItems === 0) ? <View style={styles.separator}/> 
                                              : null
         );
    }

    return (
            <SafeAreaView style={styles.container}>
                <FlatList
                    data={DATA}
                    renderItem={renderItem}
                    ItemSeparatorComponent={(e) => separator(e)}
                />
            </SafeAreaView>
    );
}

Notes:

1. If you prefer, you can choose the useState hook instead;
2. It is important to work with some key in keyExtractor property for FlatList, because it is used for caching and as the react key to track item re-ordering.

First, pass an arrow function receiving an argument. In this case, it's e, which holds the object (for instance the first):

{"highlighted":false,"leadingItem":{"id":1,"title":"Item 1"}}

So it's an easy approach, get the id and check if its %3 === 0. Take a look:

 const seperator = (e) => {
        return (
          (e.leadingItem.id % 3 == 0) ? <View style={styles.seperator}/>
                                      : null

        )
    }

And then

return (
        <SafeAreaView style={styles.container}>
            <FlatList
                data={DATA}
                renderItem={renderItem}
                keyExtractor={(items) => items.id}
                ItemSeparatorComponent={(e) => seperator(e)}
            />
        </SafeAreaView>
    );

As you can see in this working example

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