This function takes an array of properties and separates them into properties, groups and indexed groups. It returns an object, you you can later on access the array you are interested in. Example: var variableName = separateGroupsAndProperties([app.project.activeItem.selectedProperties]).groups;

separateGroupsAndProperties.jsx

function separateGroupsAndProperties (propsArray) {
    // sorting an array of props to props an group... return an object

    var resultObject = {
      all: [],
      props: [],
      groups: [],
      indexedGroups: [],
    };

    if (propsArray) {
      for (var i = 0; i < propsArray.length; i++) {
        var crntProp = propsArray[i];
        if (!crntProp) {
          continue;
        }

        switch (crntProp.propertyType) {
          case PropertyType.PROPERTY:
            resultObject.all.push(crntProp);
            resultObject.props.push(crntProp);
            break;

          case PropertyType.INDEXED_GROUP:
            resultObject.all.push(crntProp);
            resultObject.indexedGroups.push(crntProp);

          default:
            resultObject.all.push(crntProp);
            resultObject.groups.push(crntProp);
        }
      }
    }
    return resultObject;
  };