js RandomHash

/*
Example:
hash(5);
"XjJfV"

hash('xxxx-xx-xxxx-2011')
"YDFb-5e-cShX-2011"

hash = (+new Date());
console.log(hash);
1317814876299

*/

var hash = function(s) {
var n;
if (typeof(s) == 'number' && s === parseInt(s, 10)) {
s = Array(s + 1).join('x');
}
return s.replace(/x/g, function() {
var n = Math.round(Math.random() * 61) + 48;
n = n > 57 ? (n + 7 > 90 ? n + 13 : n + 7) : n;
return String.fromCharCode(n);
});
}