Reduce array of nested object by value of external object

Question

I have an array as follow:

  const myArray = [
    {
      name: 'banana',
      quotas: [
        {
          title: 'innerBanana1',
          percent: 0.3
        },
        {
          title: 'innerBanana2',
          percent: 0.4
        }
      ]
    },
    {
      name: 'apple',
      quotas: [
        {
          title: 'innerApple1',
          percent: 0.6
        },
        {
          title: 'innerApple2',
          percent: 0.2
        }
      ]
    }
  ]

I would like to sum all the percent in the quotas array only if they belong to the same external object (aka: the name is the same).

Expected Result

finalArray = [
  { name: 'banana', percent: 0.7 },
  { name: 'apple', percent: 0.8 }
]

I tried

  const sum = quotaGroups
    .map(quotaGroup => quotaGroup.quotas)
    .reduce((accumulator, groupedQuota) => {
      return accumulator + groupedQuota[0].percent
    })

But it clearly does not work. I am missing the link on how to sum only the quotas of the inner object if the name is the same

Answer 1

You needed to do the reduce inside the map, otherwise the names were getting lost, and the accumulator was trying to concatenate strings, not total up a number.

 const myArray = [ { name: 'banana', quotas: [{title: 'innerBanana1', percent: 0.3}, {title: 'innerBanana2', percent: 0.4}] }, { name: 'apple', quotas: [{title: 'innerApple1', percent: 0.6}, {title: 'innerApple2', percent: 0.2}] } ] const sum = myArray.map(quotaGroup => ({ name: quotaGroup.name, percent: quotaGroup.quotas.reduce((acc, item) => acc + item.percent, 0) })) console.log(sum)

Answer 2

Use map and reduce

 const sum = (arr) => arr.map(({ quotas, name }) => ({ name, percent: quotas.reduce((sum, { percent }) => sum + percent, 0), })); const myArray = [ { name: "banana", quotas: [ { title: "innerBanana1", percent: 0.3, }, { title: "innerBanana2", percent: 0.4, }, ], }, { name: "apple", quotas: [ { title: "innerApple1", percent: 0.6, }, { title: "innerApple2", percent: 0.2, }, ], }, ]; console.log(sum(myArray));

Answer 3

Here is what you want:

 const myArray = [ { name: 'banana', quotas: [ { title: 'innerBanana1', percent: 0.3 }, { title: 'innerBanana2', percent: 0.4 } ] }, { name: 'apple', quotas: [ { title: 'innerApple1', percent: 0.6 }, { title: 'innerApple2', percent: 0.2 } ] } ]; console.log(myArray.map(({ name, quotas }) => { return { name, percent: quotas.reduce((a, { percent }) => a + percent, 0) } }));

Answer 4

Use combination of map and reduce as below

const finalArray = myArray.map(item => ({
  name: item.name,
  percent: item.quotas.reduce((acc, cur) => acc + cur.percent, 0)
}));

Answer 5

let finalArray  = myArray.map(item => {
    let  percent = 0;
    item.quotas.forEach(function (obj) {
        percent += obj.percent
    });
    return {
        name: item.name,
        percent: percent
    }
})