javascript - Comparing sums of values inside array to determine which is the largest

Question

I am working on a coding challenge and believe I am close to a solution, but am currently stuck and would appreciate some insight. I am trying to build a function that can take a set of numbers (credit card numbers including dashes), compare the sum of each number, and return the highest credit card number. The solution must utilize Javascript. The function is currently returning "undefined". Thanks in advance for any help!

function highestCredit(creditArray){
  var highSum = 0;
  var highIndex = 0;
  var sum= 0;
  //loop through each value in the array
  for (i = 0; i < creditArray.length; i++) {
    //loop that disregards dashes and adds up the sum of a single credit card number
    for (a = 0; a < creditArray[i.length]; a++) {
      if(isNaN(creditArray[i].charAt(a)) === false){
          sum += parseInt(creditArray[i].charAt(a));
      }
    }
    //compare current sum to highest sum, update the index if there is a new high number
    if (sum >= highSum) {
      highSum = sum;
      sum = 0;
      highIndex = i;
    }
  }
  return creditArray[i];
}

console.log(highestCredit(['4916‐2600‐1804‐0530', '4779‐252888‐3972', '4252‐278893‐7978' ,'4556‐ 4242‐9283‐2260']));

Answer 1

You had some errors, see working example

  function highestCredit(creditArray) {
    var highSum = 0;
    var highIndex = 0;
    var sum = 0;
    for (i = 0; i < creditArray.length; i++) {
        for (a = 0; a < creditArray[i].length; a++) { // error with length
            if (isNaN(creditArray[i].charAt(a)) === false) {
                sum += parseInt(creditArray[i].charAt(a), 10);
            }
        }
        if (sum >= highSum) {
            highSum = sum;
            sum = 0;
            highIndex = i;
        }
    }
    return creditArray[highIndex]; // should return 'highIndex', not 'i'
}

document.write(highestCredit(['4916‐2600‐1804‐0530', '4779‐252888‐3972', '4252‐278893‐7978' ,'4556‐ 4242‐9283‐2260']));