// best function rot13(message) { var a = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; var b = "nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM"; return message.replace(/[a-z]/gi, (c) => b[a.indexOf(c)]); }