jquery-selectize.js changed dropdown identification issue-Collection of common programming errors

I did it like that. It works but I hope this is a good way for doing this.

var xhr , a;
var country, $country;
var city,  $city;

$country = $(".select2-country").selectize({
                    render: {
                        option: function(item, escape) {
                            var markup = "";
                            if (item.value !== undefined && item.value != 0) {
                                markup += ' ';
                            }
                            markup += item.text;
                            markup += '';                     
                            return markup;
                        }
                    },
                    onChange: function(value) {
                        city = $(this.$dropdown).parent().siblings('.select2-city')[0].selectize;
                        if (!value.length){city.clearOptions(); return;};                           
                        city.disable();
                        city.clearOptions();
                        city.load(function(callback) {
                                                        xhr && xhr.abort();
                                                        xhr = $.ajax({
                                                                        url: draSite + '?index.php&option=com_dratransport&view=',
                                                                        dataType: 'json',
                                                                        data:{
                                                                            selected: value,
                                                                            task: 'getCities',
                                                                        },
                                                                        success: function(results) {
                                                                            city.enable();
                                                                            callback(results);
                                                                        },
                                                                        error: function() {
                                                                            callback();
                                                                        }
                                                        });
                                                    });
                    },

              });

$city = $('.select2-city').selectize({
    valueField: 'value',
    labelField: 'text',
    searchField: ['text'],
    sortField: 'sort',
    sortDirection: 'ASC',
    diacritics:true,
});

for(var i = 0; i