how i can use for inside the append experssion?

Question

$.each(data, function(key, Citys) {
  $("#" + exchange).append(

    '<option  value="' + Citys.CityID + '"' + (Citys.CityID == CityIDes[counter] && flag == true ? " selected='selected' " : " ") + '>' +
    Citys.CityName +
    '</option>');

  if (Citys.CityID == CityIDes[counter]) {
    flag = false;
    CityIDes[counter].remove() // does not work
  }
  // }
});

i want to append cities to dropdown and select option when CityID equal to CityIdes in database.