Writing a Javascript function to find the average of digits of a number by recursion-CodePudding

I am trying to find the average the sum of digits of a number.

For example, for the number 123, the sum of digits of 123 is 6 and the number of digits in 123 is 3. So, the average of digits of 123 is 6/3 = 2.

I've only gotten as far as trying to find the sum through recursion unfortunately and often comes up as undefined. If I could figure this out I could find the average comfortably.

function averageOfDigits(number) {
//   Make the whole number into a string first to get the individual digits

  let arrOfStr = number.toString().split('');

//   Convert this array into integers
  let arrOfNum = arrOfStr.map(parseFloat)
  
// Find sum of these digits using recursion
  let sum = function sumRecursion (arrOfNum) {
    if (arrOfNum.length === 1) {
      return arrOfNum[0]
    } else {
      return arrOfNum.pop()   sum(arrOfNum)
    }
  } 
}
 

console.log(averageOfDigits(999))

CodePudding user response：

You were close. Your implementation is setting sum equal to the recursive function, so that function is never getting called inside averageOfDigits. I think the confusing part was referring to the same function by two different names.

Here I define the sum function once, then call it twice. First is the internal recursive call, and second is in the return statement.

function averageOfDigits(number) {
//   Make the whole number into a string first to get the individual digits

  let arrOfStr = number.toString().split('');

  // Convert this array into integers
  let arrOfNum = arrOfStr.map(parseFloat)
  
  // Find sum of these digits using recursion
  function sum(arrOfNum) {
    if (arrOfNum.length === 1) {
      // base case reached
      return arrOfNum[0];
    } else {
      // return first digit   recursive call
      return arrOfNum.pop()   sum(arrOfNum);
    }
  }
  
  return sum(arrOfNum);
}
 
console.log(averageOfDigits(999))

You can finish off the averageOfDigits function by replacing the return statement with your own code. Right now it just returns the sum.

CodePudding user response：

It's missing the initial call to the recursive function.

Hint:

  return (function sum(arr) {
    if (arr.length === 1) {
      return arr[0]
    } else {
      return arr.pop()   sum(arr)
    }
  }(arrOfNum))