nested-even-sum.js

// nestedEvenSum
// Write a recursive function called nestedEvenSum.
// Return the sum of all even numbers in an object which may contain nested objects.

function nestedEvenSum(obj) {
  let sum = 0;

  for (const key in obj) {
    if (Object.prototype.hasOwnProperty.call(obj, key)) {
      if (typeof obj[key] === 'number' && obj[key] % 2 === 0) sum += obj[key];
      if (typeof obj[key] === 'object') sum += nestedEvenSum(obj[key]);
    }
  }

  return sum;
}

const obj1 = {
  outer: 2,
  obj: {
    inner: 2,
    otherObj: {
      superInner: 2,
      notANumber: true,
      alsoNotANumber: 'yup'
    }
  }
};

const obj2 = {
  a: 2,
  b: { b: 2, bb: { b: 3, bb: { b: 2 } } },
  c: { c: { c: 2 }, cc: 'ball', ccc: 5 },
  d: 1,
  e: { e: { e: 2 }, ee: 'car' }
};

console.log(nestedEvenSum(obj1)); // 6
console.log(nestedEvenSum(obj2)); // 10