Your task is to add up letters to one letter. The function will be given a variable amount of arguments, each one being a letter to add. Notes: Letters will always be lowercase. Letters can overflow (see second to last example of the description) If no letters are given, the function should return 'z' fom https://www.codewars.com/kata/alphabetic…

addLetters.js

function addLetters() {
    var alphabet = "abcdefghijklmnopqrstuvwxyz".split('');
    var sum = 0;
    if(arguments.length === 0){
        console.log(alphabet[26-1]);
        return alphabet[26-1];
    }
    for (var i = 0; i < arguments.length; ++i){
        let l = arguments[i].toLowerCase();
        let t = alphabet.indexOf(l) + 1;
        sum = sum + t;
    }
    if(sum > 26){
        sum = sum % 26;
    }
    console.log(alphabet[sum - 1])
    return alphabet[sum - 1];
}