How can I sum array index values?

Question

I am new to Javascript and at the moment I'm learning how "arrays" are used.

In my code below I have 12 numbers held by an array variable. Next, the for loop is iterating over the indexes to check which values have 2 or more digits, the while-loop then summarizes the digits (e.g. value '130' at index 8, will be 1+3+0=4).

Final step..and also where I'm stuck:

I need to sum up all the "new" index values and return the result in a variable. With the numbers provided in the code, the result would be '50'.

Anyone have clue on how to do this? I've tried the conventional for-loop with sum += array[i], but it doesn't work.

var arrChars = [4, 2, 14, 9, 0, 8, 2, 4, 130, 65, 0, 1];

for (var i = 0; i < arrChars.length; i++) {
  var digsum = 0;

  while (arrChars[i] > 0) {
    digsum += arrChars[i] % 10;

    arrChars[i] = Math.floor(arrChars[i] / 10);
  }

  var sum = 0; // this last part won't work and I just get "nan", 12 times

  for (var j = 0; j < arrChars.length; j++) {
    sum += parseInt(digsum[j]);
  }

  console.log(sum); // desired output should be '50'
}

I figured that but the result from the while-loop is stored in the digsum-variable. How can the values from digsum be summarized? — cherron
– cherron, Commented Jul 14, 2022 at 12:54

Apostolos · Accepted Answer · 2022-07-14 12:53:22Z

1

Move digsum outside and it will contain the sum of every number in it:

var arrChars = [4, 2, 14, 9, 0, 8, 2, 4, 130, 65, 0, 1];

var digsum = 0;
for (var i = 0; i < arrChars.length; i++) {

  while (arrChars[i] > 0) {
    digsum += arrChars[i] % 10;

    arrChars[i] = Math.floor(arrChars[i] / 10);
  }
}
console.log(digsum); // desired output should be '50'

edited Jul 14, 2022 at 12:53

Apostolos

10.5k5 gold badges32 silver badges44 bronze badges

answered Jul 14, 2022 at 12:52

Irakli Tchedia

2791 silver badge8 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

cherron Over a year ago

Thanks! I kinda guessed this one would be solved quick but I just didn't see this obvious solution!

Heretic Monkey · Accepted Answer · 2022-07-14 12:59:48Z

1

I'd make this easy and just flatten the array of numbers into a string of digits, split that into an array of single digits, and add them together:

var arrChars = [4, 2, 14, 9, 0, 8, 2, 4, 130, 65, 0, 1];

console.log([...arrChars.join('')].reduce((agg, cur) => agg += +cur, 0));

answered Jul 14, 2022 at 12:59

Heretic Monkey

12.1k7 gold badges62 silver badges133 bronze badges

1 Comment

cherron Over a year ago

Thanks! This solution is really nice and I will definitely look into these functions as next step in my learning process.

Collectives™ on Stack Overflow

How can I sum array index values?

2 Answers 2

1 Comment

1 Comment

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Related