Caesars Cipher.js

/*One of the simplest and most widely known ciphers is a Caesar cipher, also known as a shift cipher. In a shift cipher the meanings of the letters are shifted by some set amount.

A common modern use is the ROT13 cipher, where the values of the letters are shifted by 13 places. Thus A ↔ N, B ↔ O and so on.

Write a function which takes a ROT13 encoded string as input and returns a decoded string.

All letters will be uppercase. Do not transform any non-alphabetic character (i.e. spaces, punctuation), but do pass them on.*/

function rot13(str) {
  var decoded = "";

    for(let i=0;i<str.length;i++){
         var c = str.charCodeAt(i)
     if(c >= 65 && c <= 77){
       decoded += String.fromCharCode(c + 13);
      }
     else if(c > 77 && c<=90){
       decoded += String.fromCharCode(c - 13);
      }
     else{
       decoded += String.fromCharCode(c)
      }
   }
  return decoded;
  }