Vigenère cipher

Vigenere.js

//http://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher
//https://twitter.com/r0aTzdg73QLawWw/status/290907958118842368
//https://gist.github.com/1385585

var vigenere = (function() {
  var map = Array.prototype.map;
  var canon = function(str){ return map.call(str.toUpperCase(),function(c){return c.charCodeAt(0)-65})}
  return function(source, key) {
    source = canon(source);
    key    = canon(key);
    keylen = key.length;
    return map.call(map.call(source,function(c,j) { return (c+key[j%keylen])%26}),function(c){return String.fromCharCode(c+65)}).join('');
  }
})();

//Test
alert(vigenere('ATTACKATDAWN','LEMON')+'\n'+'LXFOPVEFRNHR');