CODEWITHSUNDEEP
javascript
Justin Hensley
Justin Hensley

Reputation: 9

How do I use reduce to calculate the total of a value in an object

const people = [
    { name: 'Matt', friend: true, awesomeLevel: 10 },
    { name: 'Matias', friend: true, awesomeLevel: 10 },
    { name: 'Catie', friend: false, awesomeLevel: 3 },
    { name: 'Samantha', friend: false, awesomeLevel: 4 },
    { name: 'Jonathan', friend: true, awesomeLevel: 8 },
    { name: 'Josh', friend: true, awesomeLevel: 7 }
]


let totallyAwesome = people.reduce((acc, ele) => acc + ele.awesomeLevel)
console.log(totallyAwesome)

So I'm trying to use reduce to get the whole total added up of awesomeLevel

Upvotes: 1

Views: 37

Answers (2)

Sascha A.
Sascha A.

Reputation: 4636

You only forget the starting-value 0 in your reduce at the end as second parameter (just after the callback).

const people = [
    { name: 'Matt', friend: true, awesomeLevel: 10 },
    { name: 'Matias', friend: true, awesomeLevel: 10 },
    { name: 'Catie', friend: false, awesomeLevel: 3 },
    { name: 'Samantha', friend: false, awesomeLevel: 4 },
    { name: 'Jonathan', friend: true, awesomeLevel: 8 },
    { name: 'Josh', friend: true, awesomeLevel: 7 }
]


let totallyAwesome = people.reduce((acc, {awesomeLevel}) => acc + awesomeLevel, 0);
console.log(totallyAwesome)

Upvotes: 0

Nina Scholz
Nina Scholz

Reputation: 386883

You need to add a initialValue for the accumulator. Otherwise the first element is taken as start value for Array#reduce.

const people = [
    { name: 'Matt', friend: true, awesomeLevel: 10 },
    { name: 'Matias', friend: true, awesomeLevel: 10 },
    { name: 'Catie', friend: false, awesomeLevel: 3 },
    { name: 'Samantha', friend: false, awesomeLevel: 4 },
    { name: 'Jonathan', friend: true, awesomeLevel: 8 },
    { name: 'Josh', friend: true, awesomeLevel: 7 }
];


let totallyAwesome = people.reduce((acc, ele) => acc + ele.awesomeLevel, 0);
//                                                                       ^

console.log(totallyAwesome);

Upvotes: 1

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