Hackerrank: Caesar Cipher 1 Solution

1function caesarCipher(s, k) {
2  const lowerA = "abcdefghijklmnopqrstuvwxyz"
3  const upperA = lowerA.toUpperCase()
4
5  const res = s.split("").map(c => {
6    if (lowerA.includes(c)) {
7      return lowerA[(lowerA.indexOf(c) + k) % 26]
8    } else if (upperA.includes(c)) {
9      return upperA[(upperA.indexOf(c) + k) % 26]
10    } else {
11      return c
12    }
13  })
14
15  return res.join("")
16}