How to group by and sum an array of objects javascript?

Question


const array = [
  {
      "data": {
          "qty": "5",
          "toy": {
              "id": 3,
          },
          "available": "yes",
      }
  },
  {
      "data": {
          "qty": "5",
          "toy": {
              "id": 10,
          },
          "available": "no"
      }
  },
  {
      "data": {
          "qty": "59",
          "toy": {
              "id": 10,
          },
          "available": "yes",
      }
  },
  {
      "data": {
          "qty": "5",
          "toy": {
              "id": 3,
          },
          "available": "yes",
      }
  }
]


var result = [];
array.reduce(function(res, value) {
  if (!res['data']['toy'] || !res['data']['toy']['data']) {
    res['data'] = {...value['data'] };
    result.push(res['data'])
  }
  if (res['data']['available'] === value['data']['available'] && res['data']['toy']['id'] === value['data']['toy']['id']) {
    res['data']['qty'] = parseInt(res['data']['qty']) + parseInt(value['data'].qty)
  }
  return res;
}, {'data': {}});

console.log(result)

I am working on a js project and I need a bit of help here. From the array, How to get a new array that has qty as the sum of the other qty value which data.toy.id and available same. i.e. I want the below array. My code is not working as excepted. Changes to the same or new code are also fine. Thank you.

const array = [
  {
      "data": {
          "qty": "10",
          "toy": {
              "id": 3,
          },
          "available": "yes",
      }
  },
  {
      "data": {
          "qty": "5",
          "toy": {
              "id": 10,
          },
          "available": "no"
      }
  },
  {
      "data": {
          "qty": "59",
          "toy": {
              "id": 10,
          },
          "available": "yes",
      }
  }
]

Does this answer your question? [javascript reduce over multiple keys of objects in an array](https://stackoverflow.com/questions/51690140/javascript-reduce-over-multiple-keys-of-objects-in-an-array) — Rickard Elimää, May 20 '22 at 07:19

SSM · Accepted Answer · 2022-05-20T07:36:43.300

You group the array into an object, where the keys are concatenation of available and id properties and finally transform the object back to an array using Object.values.

const 
  array = [
    { data: { qty: "5", toy: { id: 3 }, available: "yes" } },
    { data: { qty: "5", toy: { id: 10 }, available: "no" } },
    { data: { qty: "59", toy: { id: 10 }, available: "yes" } },
    { data: { qty: "5", toy: { id: 3 }, available: "yes" } },
  ],
  result = Object.values(
    array.reduce((r, { data }) => {
      const k = data.available + data.toy.id;
      if (r[k]) {
        r[k].data.qty = String(Number(r[k].data.qty) + Number(data.qty));
      } else {
        r[k] = { data };
      }
      return r;
    }, {})
  );

console.log(result);

Yosvel Quintero · Answer 2 · 2022-05-20T07:43:57.943

0

You can use Array#reduce() to create arrayHash object using as keys: ${c.data.toy.id}-${c.data.available}

Code:

const array = [{data: {qty: '5',toy: {id: 3,},available: 'yes',},},{data: {qty: '5',toy: {id: 10,},available: 'no',},},{data: {qty: '59',toy: {id: 10,},available: 'yes',},},{data: {qty: '5',toy: {id: 3,},available: 'yes',},},]

const arrayHash = array.reduce((a, { data }) => {
  const key = `${data.toy.id}-${data.available}`
  a[key] = a[key] || { data: { ...data, qty: 0 } }
  a[key].data.qty = (+a[key].data.qty + +data.qty).toString();
  return a
}, {})
const result = Object.values(arrayHash)

console.log(result)

edited May 20 '22 at 07:43

answered May 20 '22 at 07:27

Yosvel Quintero

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1

Your solution does *not* add up the quantities of similar items. Replacing this `a[key].data.qty = c.data.qty` with `a[key].data.qty += c.data.qty` should make it work. – SSM May 20 '22 at 07:29

score 0 · Answer 3 · answered May 20 '22 at 07:32

I'd suggest using Array.reduce() to group by a key, which will be combined value of the toy id and the available property.

We'd create a map of all toys based on this key, summing the quantity for each.

Finally, we'll use Object.values() to convert back into an array.

const array = [ { "data": { "qty": "5", "toy": { "id": 3, }, "available": "yes", } }, { "data": { "qty": "5", "toy": { "id": 10, }, "available": "no" } }, { "data": { "qty": "59", "toy": { "id": 10, }, "available": "yes", } }, { "data": { "qty": "5", "toy": { "id": 3, }, "available": "yes", } } ];

const result = Object.values(array.reduce((acc, { data: { qty, toy, available } }) => { 
    const key = `${toy.id}-${available}`;
    acc[key] = acc[key] || { data: { qty: 0, toy, available } };
    acc[key].data.qty += Number(qty);
    return acc;
}, {}))

console.log('Result:', result)

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score 0 · Answer 4 · answered May 20 '22 at 08:11

I'd use just reduce

const a1 = [
  {
      "data": {
          "qty": "5",
          "toy": {
              "id": 3,
          },
          "available": "yes",
      }
  },
  {
      "data": {
          "qty": "5",
          "toy": {
              "id": 10,
          },
          "available": "no"
      }
  },
  {
      "data": {
          "qty": "59",
          "toy": {
              "id": 10,
          },
          "available": "yes",
      }
  },
  {
      "data": {
          "qty": "5",
          "toy": {
              "id": 3,
          },
          "available": "yes",
      }
  }
]

const a2 = a1.reduce((acc, it) => {
  let found = acc.find(
    dp => dp.data.toy.id === it.data.toy.id && dp.data.available === it.data.available
  )
  if(found){
    found.data.qty = ( Number(found.data.qty) + Number(it.data.qty) ).toString()
  }
  else acc.push(it)
  return acc
}, [])

console.log(JSON.stringify(a2, null,2))

How to group by and sum an array of objects javascript?

4 Answers4

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