Sum values inside of array with javascript

Question

I'm getting info from an api, and what I want to do is sum the values inside of it. Let's say that the next code:

function totalPesos(){
    $http.get('/api/valueForTest')
    .then(function(data){
        $scope.resumePesos = data.data.Response;
        //console.log($scope.resumePesos);
}

Get the next answer:

[{Id: 60, Name: Chuck, Quantity: 300},
{Id: 61, Name: Arthur, Quantity: 199},
{Id: 62, Name: John, Quantity: 450}]

What I want to do is sum the Quantity. How can I do that? I've tried with:

$scope.resumePesos.reduce(function(a,b){return a + b; });

But the answer was [object Object]

You're close, a and b are objects, you need to access the Quantity property. $scope.resumePesos.reduce((a,b) => a.Quantity + b.Quantity); — Sterling Archer
– Sterling Archer, Commented Jan 10, 2018 at 15:59
@SterlingArcher Almost. The a argument is the accumulator, so it should be: a + b.Quantity. — Nikolaj Dam Larsen
– Nikolaj Dam Larsen, Commented Jan 10, 2018 at 16:03

Mamun · Accepted Answer · 2018-01-10 16:36:35Z

2

Try the following with pure JS:

var data = [{Id: 60, Name: 'Chuck', Quantity: 300},
{Id: 61, Name: 'Arthur', Quantity: 199},
{Id: 62, Name: 'John', Quantity: 450}]
var sum = data.reduce(function(a, b){
  a += b['Quantity'];
  return a;
},0)
console.log(sum);

edited Jan 10, 2018 at 16:36

answered Jan 10, 2018 at 16:08

Mamun

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Comments

Jackson Lenhart · Accepted Answer · 2018-01-10 16:15:47Z

1

I would write it like this:

$scope.resumePesos.reduce((acc, x) => acc + x.Quantity, 0);

Remember that the 1st argument to the function passed to reduce is the accumulator, and the 2nd is each value you are iterating over, which in this case will be each object. Therefore you need to access the Quantity property of each object. Then you need to pass the initial value of the accumulator as the 2nd argument to reduce itself. Which in this case will be 0, since we want just a number as the result

answered Jan 10, 2018 at 16:15

Jackson Lenhart

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Comments

Aleksey Solovey · Accepted Answer · 2018-01-10 16:09:15Z

1

You should try this instead:

$scope.resumePesos.reduce((a,b) => {return a + b.Quantity}, 0); // Note: 0 at the end

answered Jan 10, 2018 at 16:09

Aleksey Solovey

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Comments

Tsvetan Ganev · Accepted Answer · 2018-01-10 16:10:02Z

1

You are doing two things wrong - you haven't set an initial value to the reduce function and you are summing object instead of its numerical property (.Quantity).

 var sum = $scope.resumePesos.reduce(function(acummulated, rp) {
  return accumulated + rp.Quantity; 
 }, 0);

answered Jan 10, 2018 at 16:10

Tsvetan Ganev

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Comments

Muhammed Anees · Accepted Answer · 2018-01-10 16:12:26Z

1

Just Use

$scope.sum = $scope.resumePesos.reduce(function(a,b){return a + b.Quantity; }, 0);

answered Jan 10, 2018 at 16:12

Muhammed Anees

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Comments

arunmmanoharan · Accepted Answer · 2018-01-10 16:20:25Z

1

You can use lodash and it will be useful if you want some other functions on lodash.

You can do

_.sumBy($scope.resumePesos, 'Quantity');

var data = [
  {Id: 60, Name: 'Chuck', Quantity: 300},
  {Id: 61, Name: 'Arthur', Quantity: 199},
  {Id: 62, Name: 'John', Quantity: 450}
]
  
console.log(_.sumBy(data, 'Quantity'));

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

answered Jan 10, 2018 at 16:20

arunmmanoharan

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Comments

Chuck Villavicencio · Accepted Answer · 2018-01-10 16:38:38Z

0

Thanx to all, i've tried with all your comments, and worked fine!

answered Jan 10, 2018 at 16:38

Chuck Villavicencio

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