3
\$\begingroup\$

I'm working on some practice problems using higher- order functions and while I was able to solve this problem. I can't help but think this code is ugly and not the most eloquent it could be. Is there a way to combined map and reduce is a cleaner way than I have done ? Additionally, is there any other methods or improvements I could have used here ? I'm just looking to get better and any feedback would be appreciated.

Problem: Given a number, "sumDigits" returns the sum of all its digits. If the number is negative, the first digit should count as negative.

function sumDigits(num) {

  //create array of number char
  var string = num.toString().split('');

  //if first char is negative symbol let the first numeric element be negative
  if (string[0] === "-") {
    string[1] = '-' + string[1];
    string.shift();
  }

  //convert string to int
  var toInteger = string.map(function(x) {
    return Number(x);
  });

  //get sum 
  return toInteger.reduce(function(sum, current) {
    sum += current;
    return sum;
  })
}

sumDigits(-316);

\$\endgroup\$
3
\$\begingroup\$

The key to a clean solution is to make it so that the negative sign is not a special case. Instead of splitting the string character-by-character, capture the digits, such that the first digit might be negative.

function sumDigits(num) {
  return num.toString()
            .match(/-?\d/g)
            .map(function (s) { return parseInt(s) })
            .reduce(function (a, b) { return a + b });
}

console.log(sumDigits(-316));

Also, your variable names are weird and misleading:

  • The result of .split() is an array, so don't call it a string.
  • The process of converting a string into a number (i.e. function(x) { return Number(x); }) would be appropriately called toInteger, but once you have applied the string-to-integer conversion to each element of the array, the result would be more appropriately named digits.
\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.