caesar.js

function rot13(str) { // LBH QVQ VG!
  
   str.toUpperCase();
    
    var decryptedChar="";
    var decryptedCode=0;
    var resultString="";
    for(var i = 0; i < str.length ; i++){
      
      if(str[i].charCodeAt() >= 65){//repetitive code, change later
        
        
        if(str[i].charCodeAt() >= 65 || str[i].charCodeAt() <= 90){//only convert chars between that range
         //first I sum the two values together. 
     
          decryptedChar =  String.fromCharCode(str[i].charCodeAt()+13);
          decryptedCode = decryptedChar.charCodeAt();
         //if the resulting value isn't surpassing 90, convert the char
          if(decryptedCode < 90 && decryptedCode >= 65){
            
           
            resultString += String.fromCharCode(decryptedCode);
            
          }else if(decryptedCode > 90){
            
            var startFromA =  decryptedCode - 91;//will give the number of steps to skip 
                                                 //from A
            resultString += String.fromCharCode(65+startFromA);
            
          }else if(decryptedCode == 90){
            resultString +=String.fromCharCode(decryptedCode);
          }
         //else if the resulting value is surpassing 90, do special operations. 
          
 

        }
        
       }else{
         resultString += str[i];
       }
        

      }
     return resultString;
}

// Change the inputs below to test
rot13("ARZ");

     return charCode;