Uniqid function, based on pure javascript Time and Random

uniq_id.js

//uniqId('_')
//"_jsj7byjvm1f6df87o"
//uniqId('.')
//".jsj7c2bbo0nydbmwi"
//uniqId('prefix_')
//"prefix_jsj7cdqe37ecl3eig"

function uniqId(separator){
  var separator = separator || '';
  return separator+(new Date().getTime()).toString(36)+Math.random().toString(36).substr(2, 9); 
}

//version 2
//* `uniqId2()` - returns `52643b81917b3`
//* `uniqId2('prefix_')` - returns `prefix_52643bb682821`
//* `uniqId2('prefix_', true)` - returns `prefix_52643bdf3b1fb7.38568327`

function uniqId2(pr, en) {
    var pr = pr || '', en = en || false, result, us;

    this.seed = function (s, w) {
        s = parseInt(s, 10).toString(16);
        return w < s.length ? s.slice(s.length - w) : 
                  (w > s.length) ? new Array(1 + (w - s.length)).join('0') + s : s;
    };

    result = pr + this.seed(parseInt(new Date().getTime() / 1000, 10), 8) 
                + this.seed(Math.floor(Math.random() * 0x75bcd15) + 1, 5);

    if (en) result += (Math.random() * 10).toFixed(8).toString();

    return result;
};