SOURCE

function getMaxSum(arr) {
  if (!arr.length) return 0;

  let sum = arr[0];
  let max = arr[0];

  for(let i = 1; i< arr.length; i++) {
    sum = Math.max(arr[i], arr[i] + sum);
    max = Math.max(sum, max);
  }

  return max;
}

const arr = [6,-3, -2, 7, -15, 1, 2, 2];
console.log(getMaxSum(arr));