Sum of values in javascript object

Question

I have the following javascript object

const reizen = {
personen: [
    {
        naam: "Bob",
        reizen: [
            {
                locatie: "Frankrijk",
                uitgaven: [
                    { voorwerp: "Sokken", prijs: 15 },
                    { voorwerp: "Sleutelhanger", prijs: 6 },
                    { voorwerp: "Restaurant", prijs: 26 },
                ]
            },

            {
                locatie: "Duitsland",
                uitgaven: [
                    { voorwerp: "Taxi", prijs: 30 },
                ]
            }
        ]
    },
]
}

I'm trying to get the sum of all values where it says 'prijs' (it's in dutch) Is there an 'easy' way to do this?

EDIT: Thanks everyone for the amazing replies! I got it to work thanks to you guys.

Hi! Could you give an expected output? Do you want a sum over all people, or per person? Or per location? — dbramwell
– dbramwell, Commented Apr 28, 2022 at 13:25
Can we be sure that prijs will be found in a predictable place? i.e. in an object in the uitgaven array, which is member of the objects in a reizen array etc... Most of the current answers depend on that. — Ben Stephens
– Ben Stephens, Commented Apr 28, 2022 at 13:50
@dbramwell Hi, an expected output for this one would be 77. I want the sum of all the values next to 'prijs :' — Noah
– Noah, Commented Apr 29, 2022 at 8:25
@BenStephens Yes! The 'prijs' willl always be an object in the uitgaven array, which is member of the reizen array, etc — Noah
– Noah, Commented Apr 29, 2022 at 8:27

gavgrif · Accepted Answer · 2022-04-28 14:38:15Z

Its not totally sexy - and I would not actually do this - but to give an alternative to the maps / reduces etc, especially if the object structure is variable or unknown - the simplest way to get the total count without recursion is to stringify the object (JSON.stringify), split on the "prijs' to give an array of strings that start with the target numbers and then (ignoring the first item which does not contain any targert values), parseFloat the strings (which will parse the integer characters until the first non integer character) to get the numbers and add.

const reizen = {
personen: [
    {
        naam: "Bob",
        reizen: [
            {
                locatie: "Frankrijk",
                uitgaven: [
                    { voorwerp: "Sokken", prijs: 15 },
                    { voorwerp: "Sleutelhanger", prijs: 6 },
                    { voorwerp: "Restaurant", prijs: 26 },
                ]
            },

            {
                locatie: "Duitsland",
                uitgaven: [
                    { voorwerp: "Taxi", prijs: 30 },
                ]
            }
        ]
    },
]
}

const stringifiedObj = JSON.stringify(reizen);
const portions = stringifiedObj.split('prijs\":');

let count = 0;
for(let i = 1; i < portions.length; i++) {
 count += parseFloat(portions[i])
 }
 
 console.log(count) // gives 77  (15 + 6 + 26 + 30)

This solution is so unique...I never thought about this. Thanks for posting it . I love this solution.
Might not be the most sexy solution but it's one I can work out and would work, thanks!
thanks - I am glad that it worked out for you. Happy coding :)

Hritik Sharma · Accepted Answer · 2022-04-28 13:26:47Z

const reizen = {
personen: [
    {
        naam: "Bob",
        reizen: [
            {
                locatie: "Frankrijk",
                uitgaven: [
                    { voorwerp: "Sokken", prijs: 15 },
                    { voorwerp: "Sleutelhanger", prijs: 6 },
                    { voorwerp: "Restaurant", prijs: 26 },
                ]
            },

            {
                locatie: "Duitsland",
                uitgaven: [
                    { voorwerp: "Taxi", prijs: 30 },
                ]
            }
        ]
    },
]
}

let arr = reizen.personen ;
let sum = 0;
arr.map(temp=>{
  temp.reizen.map(val=>
  val.uitgaven.map(obj=>{  if(obj.prijs)sum+=obj.prijs})
)})

console.log(sum)

Peterrabbit · Accepted Answer · 2022-04-28 13:26:54Z

Assuming your arrays could contain more that one item, you could use nested reducers:

const reizen = {
  personen: [{
    naam: "Bob",
    reizen: [{
        locatie: "Frankrijk",
        uitgaven: [{
            voorwerp: "Sokken",
            prijs: 15
          },
          {
            voorwerp: "Sleutelhanger",
            prijs: 6
          },
          {
            voorwerp: "Restaurant",
            prijs: 26
          },
        ]
      },

      {
        locatie: "Duitsland",
        uitgaven: [{
          voorwerp: "Taxi",
          prijs: 30
        }, ]
      }
    ]
  }, ]
}
const result = reizen.personen.reduce((tot, per) =>
  tot + per.reizen.reduce((acc, item) =>
    acc + item.uitgaven.reduce((res, it) => res + it.prijs, 0), 0), 0);
console.log(result);

Hans Murangaza DRCongo · Accepted Answer · 2022-04-28 13:55:40Z

0

at the level of reizen (second one)

function getTotalPrijs(reizen_){
   // var reizen_ = reizen.personen[0].reizen;
    let _prijs = 0
    reizen_.map((item, index)=>{
        const uitgaven = item.uitgaven;
        uitgaven.map(itm => typeof itm.prijs === "number"? _prijs+=itm.prijs : null)
    })
    return _prijs
}

at the level of personen (first one)

var total_prijs = 0
reizen.personen.map(item =>{
    const reizen = item.reizen;
    total_prijs+=(getTotalPrijs(reizen))
    
})

console.log(total_prijs)

edited Apr 28, 2022 at 13:55

answered Apr 28, 2022 at 13:43

Hans Murangaza DRCongo

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Comments

Ben Stephens · Accepted Answer · 2022-04-28 15:16:58Z

If you need to cope with prijs appearing in places which aren't well defined you could do something like the following using recursion:

const reizen = {"personen":[{"naam":"Bob","reizen":[{"locatie":"Frankrijk","uitgaven":[{"voorwerp":"Sokken","prijs":15},{"voorwerp":"Sleutelhanger","prijs":6},{"voorwerp":"Restaurant","prijs":26}]},{"locatie":"Duitsland","uitgaven":[{"voorwerp":"Taxi","prijs":30}]}]}]};

const random = {
  one: { prijs: 6 },
  two: [
    { prijs: 12, other: [{ prijs: 7 }, { prijs: 3 }] },
    { prijs: 2, something: 'fred' },
  ],
};

const sum_prijs = (source) =>
  Array.isArray(source) ?
    source.map(sum_prijs).reduce((a, b) => a + b) :
    Object.entries(source).reduce(
      (acc, [key, val]) =>
        acc + ((typeof val === 'object') ? sum_prijs(val) : (key === 'prijs' ? val : 0)),
      0
    );

console.log(sum_prijs(reizen));
console.log(sum_prijs(random));

Basically the same thing but without recursion:

const reizen = {"personen":[{"naam":"Bob","reizen":[{"locatie":"Frankrijk","uitgaven":[{"voorwerp":"Sokken","prijs":15},{"voorwerp":"Sleutelhanger","prijs":6},{"voorwerp":"Restaurant","prijs":26}]},{"locatie":"Duitsland","uitgaven":[{"voorwerp":"Taxi","prijs":30}]}]}]};

const random = {
  one: { prijs: 6 },
  two: [
    { prijs: 12, other: [{ prijs: 7 }, { prijs: 3 }] },
    { prijs: 2, something: 'fred' },
  ],
};

const push_concat = (array1, array2) => {
  for(let i = 0; i < array2.length; i++)
    array1.push(array2[i]);

  return array1;
};

const sum_prijs = (source) => {
  let sum = 0;
  let queue = [source];
  
  while(queue.length > 0) {
    let item = queue.pop();
    
    if(Array.isArray(item))
      push_concat(queue, item);
    else
      Object.entries(item).forEach(([key, val]) => {
        if(typeof val === 'object')
          queue.push(val);
        else if(key === 'prijs')
          sum += val;
      });
  }
  
  return sum;
};

console.log(sum_prijs(reizen));
console.log(sum_prijs(random));

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