How to sum value in javascript array object form specific search id?

Question

I have javascript array object as below. My need is to sum value base on seach id in the array object.

var array = [
{ id: 1, val: 10 }, 
{ id: 2, val: 25 }, 
{ id: 3, val: 20 }, 
{ id: 1, val: 30 }, 
{ id: 1, val: 25 }, 
{ id: 2, val: 10 }, 
{ id: 1, val: 20 }
],

For example sum of value for id 1 is 10 + 30 + 25 + 20 = 85 , It may be something link linq but I'm not sure in javascript. Thanks for all answers.

Eg. I need to sum value at id=1. So output must be 10 + 30 + 25 + 20 = 85 — Chaiwat Jo
– Chaiwat Jo, Commented Mar 7, 2019 at 8:19

nbokmans · Accepted Answer · 2019-03-07 08:36:53Z

7

You can use a combination of filter and reduce to get the result you want:

sumOfId = (id) => array.filter(i => i.id === id).reduce((a, b) => a + b.val, 0);

Usage:

const sumOf1 = sumOfId(1); //85

Reading material:

Array.prototype.filter

Array.prototype.reduce

edited Mar 7, 2019 at 8:36

answered Mar 7, 2019 at 8:17

nbokmans

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Comments

Haris Bouchlis · Accepted Answer · 2019-03-07 08:24:14Z

2

A way to do it with a traditional for loop

var array = [
  { id: 1, val: 10 }, 
  { id: 2, val: 25 }, 
  { id: 3, val: 20 }, 
  { id: 1, val: 30 }, 
  { id: 1, val: 25 }, 
  { id: 2, val: 10 }, 
  { id: 1, val: 20 }
];

var sums = {};
for (var i = 0; i < array.length; i++) {
  var obj = array[i];
  sums[obj.id] = sums[obj.id] === undefined ? 0 : sums[obj.id];
  sums[obj.id] += parseInt(obj.val);
}

console.log(sums);

running example

answered Mar 7, 2019 at 8:24

Haris Bouchlis

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1 Comment

Chaiwat Jo Over a year ago

Thank you for your kind.

Maheer Ali · Accepted Answer · 2019-03-07 08:18:43Z

1

You can use reduce() and findIndex()

var array = [
{ id: 1, val: 10 }, 
{ id: 2, val: 25 }, 
{ id: 3, val: 20 }, 
{ id: 1, val: 30 }, 
{ id: 1, val: 25 }, 
{ id: 2, val: 10 }, 
{ id: 1, val: 20 }
];
let res = array.reduce((ac,a) => {
  let ind = ac.findIndex(x => x.id === a.id);
  ind === -1 ? ac.push(a) : ac[ind].val += a.val;
  return ac;
},[])
console.log(res);

answered Mar 7, 2019 at 8:18

Maheer Ali

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1 Comment

Chaiwat Jo Over a year ago

Thank you for your kind.

thp44 · Accepted Answer · 2021-07-22 08:38:52Z

1

JS noob here ... I guess something like this should be here too :-)

let newArray = {}
array.forEach((e) => {
    !newArray[e.id] && (newArray[e.id] = 0);
    newArray[e.id] += e.val;
  });

answered Jul 22, 2021 at 8:38

thp44

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Comments

aaaaane · Accepted Answer · 2019-03-07 08:20:27Z

0

You can loop on the array and check the ids.

var array = [
  { id: 1, val: 10 }, 
  { id: 2, val: 25 }, 
  { id: 3, val: 20 }, 
  { id: 1, val: 30 }, 
  { id: 1, val: 25 }, 
  { id: 2, val: 10 }, 
  { id: 1, val: 20 }
];

var sum = 0;
var id = 1;

$.each(array, function(index, object){
  if (object.id == id) {
    sum += object.val;
  }
});

console.log(sum);

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

answered Mar 7, 2019 at 8:20

aaaaane

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1 Comment

Chaiwat Jo Over a year ago

Thank you for your kind.

kemicofa · Accepted Answer · 2019-03-07 08:27:50Z

0

Using Array#reduce and Map you can get the sum for each id like so. This also uses destructuring to have quicker access to properties.

const data=[{id:1,val:10},{id:2,val:25},{id:3,val:20},{id:1,val:30},{id:1,val:25},{id:2,val:10},{id:1,val:20}];

const res = data.reduce((a,{id,val})=>{
  return a.set(id, (a.get(id)||0) + val);
}, new Map())

console.log(res.get(1));
console.log(res.get(2));

If you wanted to output all the sums, then you need to use Array#from

const data=[{id:1,val:10},{id:2,val:25},{id:3,val:20},{id:1,val:30},{id:1,val:25},{id:2,val:10},{id:1,val:20}];

const res = Array.from(
  data.reduce((a,{id,val})=>{
    return a.set(id, (a.get(id)||0) + val);
  }, new Map())
);

console.log(res);

If the format should be similar as to your original structure, you need to add a Array#map afterwards to transform it.

const data=[{id:1,val:10},{id:2,val:25},{id:3,val:20},{id:1,val:30},{id:1,val:25},{id:2,val:10},{id:1,val:20}];

const res = Array.from(
  data.reduce((a,{id,val})=>{
    return a.set(id, (a.get(id)||0) + val);
  }, new Map())
).map(([id,sum])=>({id,sum}));

console.log(res);

answered Mar 7, 2019 at 8:27

kemicofa

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1 Comment

Chaiwat Jo Over a year ago

Thank you for your kind.

Nina Scholz · Accepted Answer · 2019-03-07 08:33:12Z

0

You could take GroupBy from linq.js with a summing function.

var array = [{ id: 1, val: 10 }, { id: 2, val: 25 }, { id: 3, val: 20 }, { id: 1, val: 30 }, { id: 1, val: 25 }, { id: 2, val: 10 }, { id: 1, val: 20 }],
    result = Enumerable
        .From(array)
        .GroupBy(null, null, "{ id: $.id, sum: $$.Sum('$.val') }", "$.id")
        .ToArray();

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

<script src="https://cdnjs.cloudflare.com/ajax/libs/linq.js/2.2.0.2/linq.js"></script>

edited Mar 7, 2019 at 8:33

answered Mar 7, 2019 at 8:24

Nina Scholz

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1 Comment

Chaiwat Jo Over a year ago

Thank you for your kind.

3limin4t0r · Accepted Answer · 2019-03-07 10:40:50Z

Here is another option, introducing an Array.prototype.sum helper:

Array.prototype.sum = function (init = 0, fn = obj => obj) {
    if (typeof init === 'function') {
        fn = init;
        init = 0;
    }

    return this.reduce(
        (acc, ...fnArgs) => acc + fn(...fnArgs), 
        init
    );
};

// .sum usage examples
console.log(
    // sum simple values
    [1, 2, 3].sum(),
    // sum simple values with initial value
    [1, 2, 3].sum(10),
    // sum objects
    [{ a: 1 }, { a: 2 }, { a: 3 }].sum(obj => obj.a),
    // sum objects with initial value
    [{ a: 1 }, { a: 2 }, { a: 3 }].sum(10, obj => obj.a),
    // sum custom combinations
    [{ amount: 1, price: 2 }, { amount: 3, price: 4 }]
        .sum(product => product.amount * product.price)
);

var array = [{ id: 1, val: 10 }, { id: 2, val: 25 }, { id: 3, val: 20 }, { id: 1, val: 30 }, { id: 1, val: 25 }, { id: 2, val: 10 }, { id: 1, val: 20 }];

// solutions
console.log(
    array.filter(obj => obj.id === 1).sum(obj => obj.val),
    array.filter(({id}) => id === 1).sum(({val}) => val),
    array.sum(({id, val}) => id === 1 ? val : 0)
);

references:

Array.prototype.reduce
Array.prototype.filter
Arrow functions used in sum(obj => obj.val)
Object destructing assignment used in ({id}) => id === 1
Rest parameters used in (acc, ...fnArgs) => acc + fn(...fnArgs)
Conditional (ternary) operator used in id === 1 ? val : 0

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