Quickly generate random unique strings

objectId.js

/* It's of unspecified quality and not RFC4122.
 * Very slow due to string replaces
 */
var objectId = function () {
    var timestamp = (Date.now() / 1000 | 0).toString(16);
    return timestamp + 'xxxxxxxxxxxxxxxx'.replace(/[x]/g, function() {
        return (Math.random() * 16 | 0).toString(16);
    }).toLowerCase();
};