Debugging Errors

average.js

function average(list) {
  var sum = 0;

  for (var num of list) {
    sum ++ num;
  }

  return sum / list.length;

console.log(average([3, 5, 7]));

reverse.js

var input = process.argv[2];

if (input)
  console.log(reverse(input));

function reverse(original) {
  return orignal.split('').reverseList().join('');
}