方法一：

function rot13(str) { // LBH QVQ VG!
function rot13char(char){
    if (char.charCodeAt()>=65&&char.charCodeAt()<=90){
      return char.charCodeAt()>=78?String.fromCharCode(char.charCodeAt()-13):String.fromCharCode(char.charCodeAt()+13);
    }else
      return char;
  }
  str=str.split("").map(rot13char).join("");
  return str;
}
// Change the inputs below to test
rot13("SERR PBQR PNZC");

方法二：

function rot13(str) { // LBH QVQ VG!
  var len = str.length,
      rStr = '';
  for(var i=0;i<len;i++){
    var n = str.charCodeAt(i),
        c = str.charAt(i);
    if(n >64 && n<91){
      if(n+13<91){
        c = String.fromCharCode(n+13);
      }else{
        c = String.fromCharCode(64+n+13-90);
      }
    }
    rStr+=c;
  }
  return rStr;
}


// Change the inputs below to test
rot13("SERR PBQR PNZC");