code: function () {
          var keys = [];
          for (var i = 0, len = localStorage.length; i < len; i++) {
              var key = localStorage.key(i);
              var splits = key.split('-');
              if (splits[0] === _storage_key_prefix) {
                  var timestamp = parseFloat(splits[1]);
                  keys.push({
                      timestamp: timestamp,
                      key: key,
                      // override valueOf function to make value comparison work for binaryIndexOf
                      valueOf: function () { return this.key; },
                      // override toString to make default sort method correct and fast
                      toString: function () { return this.key.toString(); }
                  });
              }
          }
  
          keys.sort();
          return keys;
      }
docs: 10 seconds