for indesign select next item in group object

sel_next_ingroup.js

/**
 * select next object in group object 
 */

#target 'InDesign'
// select a pageitem in group object
if (app.selection.length === 0) {exit();};
if (app.selection[0].parent.constructor.name !== 'Group') {exit()};
 
var current_sel = app.selection[0];
var current_id = current_sel.id;
var parent_group = current_sel.parent;
for (var i=0, iL=parent_group.pageItems.length; i < iL ; i++) {
	if (parent_group.pageItems[i].id === current_id) {// current object
		// select next object
		parent_group.pageItems[(i+1)%iL].select();
	};
};