var nums = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; function sum_recurse(arr, i) { i = i || 0; if (i > arr.length) return 0; else return arr[i] + sum_recurse(arr, i + 1); } function sum_while(arr) { var total = 0, i = 0, len = arr.length; while (i < len) { total += arr[i++]; } return total; } function sum_for(arr) { var total = 0, len = arr.length; for (var i = 0; i < len; i++) { total += arr[i]; } return total; }