try below code
var doc = app.activeDocument;
var myPage = doc.pages
var myModul = doc.groups.item("modul");
for(var i = 0; myPage.length>i ;i++){
var allItems =myPage[i].allPageItems
for(var j=0;j<allItems.length;j++)
{
var myGroup = allItems[j];
if(myGroup.label =="modul"){
$.writeln("Constructor: "+myGroup.constructor.name);
app.select(myGroup);
}
}
}