returns the id(s) of the selected item(s)
| as_array | boolean | specifies whether the result should always be returned as an array. The default value is false |
| string|array | the single item id or an array of ids |
//single select mode
var id = list.getSelectedId(); // id = someid
//multiselect mode
var id = list.getSelectedId(); // id = [someid1, someid2, someid3]