code: function keys(object) {
          var locations = [],
              replacement,
              pos;
  
          for(var location in object) {
              if (object.hasOwnProperty(location)) {
                  locations.push(location);
              }
          }
  
          // numeric descending
          return locations.sort(function(a, b) {
              return b - a;
          });
      }
docs: sorts an object by index descending
  
  @param {Object} object
  @return {Array}