select2

jQuery('#parentId').select2({
        placeholder: 'Please select a parent department',
        allowClear: true,
        ajax: {
          url: url,
          dataType: 'json',
          delay: 250,
          data: function (params) {
            return {
              q: params.term,
            };
          },
          processResults: function (data) {
            var formatParents = [];
            jQuery.each(data.parents, function(index, item) {
                formatParents.push({id: item.department_id, text: item.parent});
            });

            return {
              results: formatParents
            };
          },
          cache: true
        },
        minimumInputLength: 1,
      });