Caesar cipher

Easy TimeO(n) SpaceO(n)

Given a string s and a number shift, return the string with every letter moved that many places forward through the alphabet, wrapping from z back round to a. Each letter keeps its case, so an uppercase letter stays uppercase and a lowercase one stays lowercase. Digits, punctuation and spaces are left untouched and appear in the answer exactly as they went in.

Examples

Example 1

Input
s = "Hello, World!"shift = 3
Output
"Khoor, Zruog!"
Every letter moves three places; the comma, the space and the exclamation mark are copied as they stand.

Example 2

Input
s = "xyz"shift = 3
Output
"abc"
All three run past the end of the alphabet and come back round to its start.

The Code

function caesar(s, shift) {
  const A = 65;
  const a = 97;
  let out = "";
  for (let i = 0; i < s.length; i++) {
    const code = s.charCodeAt(i);
    if (code >= a && code <= a + 25) {
      out += String.fromCharCode(((code - a + shift) % 26) + a);
    } else if (code >= A && code <= A + 25) {
      out += String.fromCharCode(((code - A + shift) % 26) + A);
    } else {
      out += s[i];
    }
  }
  return out;
}
caesar("Hello, World!", 3);
Done

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