Caesar Cipher Algorithm

rot13.js

function rot13(name) {
if (name.length === 0) return "Submission cannot be empty.";
let alphabet = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"];
let res = [];
name = name.toLowerCase().split("");
for (let i = 0; i < name.length; i++) {
	for (let j = 0; j < alphabet.length; j++) {
		if (name[i] === alphabet[j]) {
			if (alphabet[j + 13] === undefined) {
				res.push(alphabet[j - 13]);
			} else res.push(alphabet[j + 13]);
			}
		}
	}
	return res.join("");
}
console.log(rot13("HELLO"));