caesar cipher javascript

1function rot13(str) {
2var charcode = [];
3var words = [];
4
5for(let i = 0; i < str.length; i++){
6  
7  var asc = str.charCodeAt(i)
8  
9  charcode.push(asc)
10}
11var converted = charcode.map(function(a){
12  return a-13
13})
14console.log(converted)
15converted.forEach((letter)=>{
16 if(letter >= 65){
17  var final =String.fromCharCode(letter)
18  words.push(final)
19 }
20 else if(letter>=52){
21   final = String.fromCharCode(letter+26)
22   words.push(final)
23 }
24 else {
25   final = String.fromCharCode(letter+13)
26   words.push(final)
27 }
28 
29})
30return words.join("")
31}
32
33console.log(rot13("SERR YBIR?"));

1   var myCipher = [];
2      var myArray = []; 
3      
4      for (i=0; i < str.length; i++) {
5        // convert character - or don't if it's a punctuation mark.  Ignore spaces.
6        if (str.charCodeAt(i) > 64 && str.charCodeAt(i) < 78) {
7             myArray.push(String.fromCharCode(str.charCodeAt(i) + 13));
8         } else if (str.charCodeAt(i) > 77 && str.charCodeAt(i) < 91) { 
9             myArray.push(String.fromCharCode(77 - (90 - str.charCodeAt(i))));
10         } else if (str.charCodeAt(i) > 32 && str.charCodeAt(i) < 65) {
11             myArray.push(str.charAt(i));
12         }
13       
14        // push word onto array when encountering a space or reaching the end of the string
15        
16        if (str.charCodeAt(i) == 32) {
17          myCipher.push(myArray.join(''));
18          myArray.length = 0;      
19        }
20        
21        if (i == (str.length - 1)) {
22           myCipher.push(myArray.join(''));
23        }
24
25      }
26
27      return myCipher.join(" ");
28      
29    }