How to find sum of numbers in string stored in array

Question

I have figured out how to calculate the value of numbers from a single string, using as an example..

var sum = \"13-2-10-7-3\".split(\'-\').reduce(function(x, y)         


        

Answer 1

Loop over the credit card numbers and check if sum is max store it and continue to loop and store the maximum credit card number and return it:

function max_credit_sum(arr){
  max = -1
  credit_card = ''
  for(ele of arr){
    numbers = ele.replace(/-/g, '').split('')
    sum = 0
    for(num of numbers){
      sum += parseInt(num)
    }
    if(sum >= max){
      credit_card = ele
      max = sum
    }
  }
 return credit_card
}

// Test
arr = ['4916-2600-1804-0530', '4779-252888-3972', '4252-278893-7978', '4556-4242-9283-2260'] 
maximum = max_credit_sum(arr)

Answer 2

You could write a maxBy function, which takes your function as a parameter for determining the maximum element in the array. This would let you easily adapt your code without much work.

var cards = ['4916-2600-1804-0530', '4779-252888-3972', '4252-278893-7978', '4556-4242-9283-2260'];

function maxBy(arr, func) {
  return arr.reduce(function(max, val) {
    return func(val) >= func(max) ? val : max;
  }, arr[0]);
}

function sumCC(card) {
  return card.split(/-|/).reduce(function(sum, val) {
    return sum + parseInt(val, 10);
  }, 0);
}

console.log(maxBy(cards, sumCC));

This is a useful utility function. The Lodash utility library also provides a _.maxBy.

Answer 3

You might get the card with maximum sum like this;

var cards = ['4916-2600-1804-0530', '4779-252888-3972', '4252-278893-7978', '4556-4242-9283-2260'],
 cardSums = cards.map(c => c.split("-").reduce((p,c) => +p + +c)),
  maxCard = cards[cardSums.indexOf(Math.max(...cardSums))];
console.log(maxCard);

Answer 4

Its not the most performant, but its simple and quick

       
var ccs = ['4916-2600-1804-0530', '4779-252888-3972', '4252-278893-7978', '4556-4242-9283-2260']

// FSFL = F*Simple For-Loop
var sum = (a, b) => a + b;
var largestSum = 0; 
var largestSumLastIdx = 0;
for (let i = 0; i < ccs.length; i++) {
   let s = ccs[i].split(/-|/).map(Number).reduce(sum, 0);
   if (s >= largestSum) {
     largestSum = s;
     largestSumLastIdx = i;
   }
}

console.log("The winner is: " + ccs[largestSumLastIdx])