Sum array of objects with dynamic keys - Javascript

Question

I've got the following array

arr = [
  { 'Atencion Personalizada': 2, 'Caja': 3 },
  { 'Atencion Personalizada': 1 },
  { 'Tarifa Social': 3 }
]

Expected output: 9

And I would like to sum the properties the shortest way possible. The thing is that the object keys are always variable so i can't go for:

arr.reduce((acc,item) => acc+item.keyName)

Found this post but can't adapt the code to my solution either:

var data = [{ A: 4, B: 2 }, { A: 2, B: 1 }, { A: 3, B: 1 }, { A: 2, B: 1, C: 1 }],
    result = data.reduce((r, o) => (Object.entries(o).forEach(([k, v]) => r[k] = (r[k] || 0) + v), r), {});

Thank you in advance

@Andy answer i'm looking is 9

juanmac
– juanmac

2021-08-31 20:16:44 +00:00
Commented Aug 31, 2021 at 20:16 — juanmac
– juanmac, Commented Aug 31, 2021 at 20:16

Invizi · Accepted Answer · 2021-08-31 20:12:33Z

3

Here's my solution. Map through the array and flatten the properties values, then reduce them.

const arr = [
  { 'Atencion Personalizada': 2, 'Caja': 3 },
  { 'Atencion Personalizada': 1 },
  { 'Tarifa Social': 3 }
]

console.log(arr.flatMap(e => Object.values(e)).reduce((a, b) => a + b));

answered Aug 31, 2021 at 20:12

Invizi

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1 Comment

juanmac Over a year ago

This is what I was loking for, thanks! It seem easier in my head than it really was

James · Accepted Answer · 2021-08-31 20:19:55Z

1

Use reduce twice, once on the outer array and once on the values of each object inside it.

const arr = [
  { 'Atencion Personalizada': 2, 'Caja': 3 },
  { 'Atencion Personalizada': 1 },
  { 'Tarifa Social': 3 }
];
const total = arr.reduce((gt, item) => 
  gt + Object.values(item).reduce((t, sub) => t + sub, 0)
, 0);

console.log(total);

answered Aug 31, 2021 at 20:19

James

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Comments

Joseph Coppin · Accepted Answer · 2021-08-31 19:58:38Z

0

Maybe something like this?

let acc = {};
for (let o of arr) for (let key in o) {
    acc[key] ??= 0;
    acc[key] += o[key];
}

Not a one-liner though

answered Aug 31, 2021 at 19:58

Joseph Coppin

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3 Comments

juanmac Over a year ago

Yeah, thoght of that but I'm trying to improve my javascript skills. Thak's!

Andy Over a year ago

@juanmac, there's nothing wrong with making code make more sense. One-liners are difficult to comprehend.

Community Over a year ago

Please provide additional details in your answer. As it's currently written, it's hard to understand your solution.

jircdeveloper · Accepted Answer · 2021-08-31 20:01:14Z

0

You can do something like this:

total = arr.reduce((acc,item) => {
     const values = Object.values(item)
     values.forEach(item=> acc += item)
    return acc;
}, 0);

Check I passed the first value (0) as the second parameter to reduce method.

answered Aug 31, 2021 at 20:01

jircdeveloper

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Comments

Rateb Habbab · Accepted Answer · 2021-08-31 20:04:23Z

0

Hope this would help:

arr = [
  { 'Atencion Personalizada': 2, 'Caja': 3 },
  { 'Atencion Personalizada': 1 },
  { 'Tarifa Social': 3 }
]

 var sum = arr.map(item => {
    var x = 0
    for (const [key, value] of Object.entries(item)) {
        x+=value
    }
    return x
}).reduce( (acc, curr) => acc + curr)
console.log(sum)

answered Aug 31, 2021 at 20:04

Rateb Habbab

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Comments

Mario Varchmin · Accepted Answer · 2021-08-31 20:10:37Z

0

arr = [
  { 'Atencion Personalizada': 2, 'Caja': 3 },
  { 'Atencion Personalizada': 1 },
  { 'Tarifa Social': 3 }
]
var total = 0;
arr.forEach((x, i) => 
    total += Object.values(x).reduce((a,b) => a+b)
);
console.log(total)

edited Aug 31, 2021 at 20:10

Mario Varchmin

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answered Aug 31, 2021 at 20:03

theunknownSAI

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Comments

TAHER El Mehdi · Accepted Answer · 2021-09-28 19:30:26Z

0

Solve it with this approach:

use JSON.stringify to get arr as string.
extract numbers with match with regex \d+ and flag g to return it as group.
map it to real numbers rather than string.
reduce it to the sum of all numbers.

JSON.stringify(arr) //'[{"Atencion Personalizada":2,"Caja":3},{"Atencion Personalizada":1},{"Tarifa Social":3}]'
.match(/\d+/g) //['2', '3', '1', '3']
.map(Number) //[2, 3, 1, 3]
.reduce((acc, n)=>acc+n, 0) //9

answered Sep 28, 2021 at 19:30

TAHER El Mehdi

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