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('');
}