JavaScript recursive function is returning strange value

Here is my code, why it is returning 13 in place of 4:

const superNumber = (n) => {
  let nums = n.toString().split('').map(Number);
  let sum = parseInt(nums.reduce((x, y)=> x + y));
  console.log('Nums: ',nums, 'Sum: ', sum);
  if(sum > 9) {
     superNumber(sum);
  }
   return sum;
}

let result = superNumber(148);
console.log('Ans: ', result);

Here is the console log:

• Nums: [1, 4, 8] Sum: 13
• Nums: [1, 3] Sum: 4 // Calculated sum
  correctly but returning the previous value
• Ans: 13

>Solution :

You forgot a return there

if (sum > 9) 
    return superNumber(sum); // Here you forgot to return

const superNumber = (n) => {
  let nums = n.toString().split('').map(Number);
  let sum = parseInt(nums.reduce((x, y) => x + y));
  console.log('Nums:', nums.toString(), ' Sum:', sum);
  if (sum > 9) {
    return superNumber(sum);
  }
  return sum;
}

let result = superNumber(148);
console.log('Ans: ', result);