ROT13

[soonlive]

ROT13

Description:

How can you tell an extrovert from an introvert at NSA? Va gur ryringbef, gur rkgebireg ybbxf ng gur BGURE thl'f fubrf.

I found this joke on USENET, but the punchline is scrambled. Maybe you can decipher it? According to Wikipedia, ROT13 (http://en.wikipedia.org/wiki/ROT13) is frequently used to obfuscate jokes on USENET.

Hint: For this task you're only supposed to substitue characters. Not spaces, punctuation, numbers etc. Test examples:

Test.expect(rot13("EBG13 rknzcyr.") == "ROT13 example.");
Test.expect(rot13("This is my first ROT13 excercise!") == "Guvf vf zl svefg EBG13 rkprepvfr!")

题意：

将字符串中的字母替换为在26个字母表中向右移动13个位置后的字母，区分大小写

Solution：

function rot13(str) {
  return str.split('').map(function (n) {
      if(/[A-Za-z]/.test(n)){
          var charCode = n.charCodeAt(0);
          n = String.fromCharCode(charCode>109 || (charCode>77 && charCode<91)?charCode-13:charCode+13);
      }
      return n;
  }).join('');
}