如何在jquery.autocomplete.js中传递动态参数

Question

我正在使用autocomplete进行自动选择城市和地区的项目。我想现在动态自动选择所选城市的区域。尽管自动搜索工作得很好，但我还是无法为该地区发送动力城市。我该怎么做？我尝试了this stack answer中给出的选项，但没有用。我的代码到目前为止：

HTML 的

<input type="hidden" id="hid_search_city_id" name="hid_search_city_id" value="">

SCRIPT

$(document).ready(function(e) {
    $("#hid_search_city_id").change(function() {
        areas.setOptions({
            params: {
                entity_type: $('#hid_search_city_id').val()
            }
        });
    });
});
var baseUrl = $('input#baseUrl').val();
var url = baseUrl + 'ajax/getSearchCities';
$('input#search_cities').autocomplete({
    serviceUrl: url,
    minChars: 1,
    delimiter: /(,|;)\s*/,
    maxHeight: 400,
    width: 300,
    deferRequestBy: 0,
    onSelect: function(value, data) {
        $('#id').val(+data);
        $('#hid_search_city_id').val('');
        $('#hid_search_city_id').val(data);
    }
})
var url = baseUrl + 'ajax/getSearchAreas';
var areas = $('input#search_areas').autocomplete({
    serviceUrl: url,
    minChars: 1,
    delimiter: /(,|;)\s*/,
    maxHeight: 400,
    width: 300,
    params: {
        entity_type: $('#hid_search_city_id').val()
    },
    deferRequestBy: 0,
    onSearchStart: function(q) {
        areas.entity_type = $('input#search_cities').val();
    },
    onSelect: function(value, data) {
        $('#id').val(+data);
    },
});
areas.setOptions({
    params: {
        entity_type: $('#hid_search_city_id').val()
    }
});