Ceaser Cipher返回错误的输出

Question

它假设给予“自由的爱”！而是返回“FREE LOVEL”。 其他一些输出是正确的：例如OutPut：:(“SERR CVMMN！”）和（“GUR DHVPX OEBJA QBT WHZCRQ BIRE GUR YNML SBK。”

function rot13(str) { // LBH QVQ VG!
  var result = [];
  var a = str.split(" ");

  for (i = 0; i < a.length; i++) {
    var b = a[i].split("");
    result[i] = b;
  }
  //return result;
  //var result2 = [ ];
  for (i = 0; i < result.length; i++) {
    for (j = 0; j < result[i].length; j++) {
      result[i][j] = result[i][j].charCodeAt() + 13;
      if (result[i][j] < 65) {
        result[i][j] = result[i][j] - 13; //'?' should revert back to 63***emphasized text*
      }
      //else if(result[i][j] == )
      else if (result[i][j] > 90) {
        result[i][j] = result[i][j] - 26;
      }

    }

  }
  for (i = 0; i < result.length; i++) {
    for (j = 0; j < result[i].length; j++) {
      result[i][j] = String.fromCharCode(result[i][j]);
    }
  }
  for (i = 0; i < result.length; i++) {
    var d = result[i];
    var c = d.join("");
    result[i] = c;
  }
  //return result;
  for (i = 0; i < result.length; i++) {
    result = result.join(" ");
    return result;
  }
}

// Change the inputs below to test
console.log(rot13("SERR YBIR?"));
console.log(rot13("GUR DHVPX OEBJA QBT WHZCRQ BIRE GUR YNML SBK."))