uuid2

 .factory('uuid2', [function() {
        function s4() {
            return Math.floor((1 + Math.random()) * 0x10000)
                .toString(16)
                .substring(1);
        }

        return {
            newuuid: function() {
                // http://www.ietf.org/rfc/rfc4122.txt
                var s = [];
                var hexDigits = "0123456789abcdef";
                for (var i = 0; i < 36; i++) {
                    s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1);
                }
                s[14] = "4"; // bits 12-15 of the time_hi_and_version field to 0010
                s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1); // bits 6-7 of the clock_seq_hi_and_reserved to 01
                s[8] = s[13] = s[18] = s[23] = "-";
                return s.join("");
            },
            newguid: function() {
                return s4() + s4() + '-' + s4() + '-' + s4() + '-' +
                    s4() + '-' + s4() + s4() + s4();
            }
        }
    }])