recursion in nested javascript object

Question

find the addition of nested object using recursion here my sum is always passed as 10 ??......... I am trying to add sum value in else condition but in if it always pass as 10

let abc = { a: 10, b: { a: 20 }, c: { b: { a: 30 } } };
const Formation = (obj,sum) =>{
 for(let ky in obj) {
 if (typeof obj[ky] == 'object') {
 Formation(obj[ky],sum);
 } else {
 sum += obj[ky] ? obj[ky] : 0;
 }
 // console.log(sum)
 }
 return sum;
}
console.log('res: ', Formation(abc, 0));

• Alexander Paschenko: You need replace Formation(obj[ky],sum); with sum += Formation(obj[ky],sum);

Answer 1

Yes, it's because you don't use returned value from nested Formation. You need make some changes to your code:

let abc = { a: 10, b: { a: 20 }, c: { b: { a: 30 } } };
const Formation = (obj) =>{
 let sum = 0;
 for(let ky in obj){
 if(typeof obj[ky] == 'object'){
 sum += Formation(obj[ky]);
 }
 else{
 sum += obj[ky] ? obj[ky] : 0;
 
 }
 // console.log(sum)
 }
 return sum;
}