Get the sum total of a value from flatlist react native-CodePudding

I am trying to get the sum total of all the value retrieve from my fetch in a FlatList below is my code.

<SafeAreaView style={styles.container}>
    <FlatList
        data={numList}
        listKey="number-list"
        keyExtractor={item => item.id}
        renderItem={({ item }) => {
            return (
                <View style={styles.ticSec}>
                    <Text>{item.amount}</Text>
                </View>
            )
        }}
    />
</SafeAreaView>

The Output result:

10
20
15

How can I make it output sum total of of 45 whick is the sometotal of 10,20,15

thank you for you help

CodePudding user response：

User Array.prototype.reduce to calculate the sum of the amounts of all items in your numList like so:

const sumTotal = numList.reduce((acc, next) => {
  return acc   next.amount
}, 0)

where acc stands for accumulator and next is the next item we iterate over.

you can then use the value in your jsx:

<Text>{sumTotal}</Text>

More about reduce: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce