How find sum of all values in object and included objects in array?

Question

How find sum of all value in that object? In object included array with another object with value and may be "next" array with similar structure object.

{
  value: 4,
  next: [
    {
      value: 3,
      next: [...]
    },
    {
      value: 3,
      next: [...]
    },
    ...
  ]
}

Answer 1

You would need recursion to deal with the arbitrary nesting of your object:

 const nestedSum = o => (o.next || []).reduce((acc, o) => acc + nestedSum(o), o.value); // Demo const data = { value: 4, next: [{ value: 3, next: [{value: 5}] }, { value: 3, next: [] }, ] }; console.log(nestedSum(data)); 

Answer 2

Use reduce and Object.entries to sum the values recursively:

 const obj = { value: 4, next: [{ value: 3, next: [{ value: 1 }] }, { value: 3, next: [{ value: 2, next: [] }] }] }; const sum = (obj) => Object.entries(obj).reduce((acc, [k, v]) => acc + ( k === 'next' ? v.map(sum).reduce((s, x) => s + x, 0) : k === 'value' ? v : 0) , 0); console.log(sum(obj)); 

Answer 3

 function sum(obj, current = 0) { const nextSum = (obj.next || []).reduce((nextSum, obj) => nextSum + sum(obj, current), 0) return current + nextSum + obj.value } const example = { value: 4, next: [ { value: 3, next: [{ value: 7 }] }, { value: 3 } ] } console.log(sum(example)) // must be 17 

Answer 4

You need a recursive function and check if the value of a key is a number then add with the variable , else if it is an array like next then iterate through it and again call the same function with a new object

 let data = { value: 4, next: [{ value: 3, next: [{ value: 4 }, { value: 5 }] }, { value: 3, next: [{ value: 2 }] } ] } let sum = 0; function findSum(obj) { for (let keys in obj) { if (typeof obj[keys] === 'number') { sum += obj[keys]; } else if (Array.isArray(obj[keys]) && obj[keys].length > 0) { obj[keys].forEach(function(item) { findSum(item) }) } } } findSum(data); console.log(sum) 

Answer 5

The structure of your object is called tree Tree (data structure) . You can use breadth-first or depth-first approach to traverse the tree and gather the sum along the way.

Other answers say you have to go recursively but you can do it iteratively with the breadth-first approach, I show you both approaches down in the code snippet.

I've expanded your data sample adding null values where there is supposedely no next values (you could use any kind of check really).

 let data = { value: 4, next: [ { value: 3, next: [ { value: 5, next: null }, { value: 6, next: null } ] }, { value: 2, next: [ { value: 2, next: null }, { value: 3, next: [ { value: 7, next: null }, { value: 8, next: null } ] } ] } ] } // iterative approach function breadthFirst(node){ let sum = 0 let q = [node] while(q.length > 0){ let node = q.pop() sum += node.value if (node.next !== null) { for (let other of node.next){ q.push(other) } } } return sum } console.log('breadthFirst sum (iterative):', breadthFirst(data)) // recursive apporach function depthFirst(node){ let sum = 0 function recursion(node){ sum += node.value if (node.next !== null) { for (let other of node.next){ recursion(other) } } } recursion(node) return sum } console.log('depthFirst sum (recursive):', depthFirst(data))