使用layui组件和自定义控制器去实现联动菜单。方便二次开发，要更换select下拉框的样式可以看看，可以用在表单或者自定义控制器去使用。

php部分，用来去分类查找一级菜单对应的二级菜单内容
public function areaInfo(){
        $id = $_GET['id'];
        if ($id > 0) {
            $data = \Phpcmf\Service::M()->db->table('linkage_data_1')
                    ->select('id,name')
                    ->where('pid', $id)
                    ->get()->getResultArray();
            return json_encode($data);
        }else if ($id == 'undefined' || $id == ' '){
            $data = \Phpcmf\Service::M()->db->table('linkage_data_1')
                    ->select('id,name')
                    ->where('pid', 0)
                    ->get()->getResultArray();
            return json_encode($data);
        }
    }

html部分
<div class="layui-form-item">
                        <label class="layui-form-label">实际居住地</label>
                        <div class="layui-input-inline">
                            <select name="data[residence]"  lay-filter="province" id="province">
                                <option value="">请选择省份</option>
                            </select>
                        </div>
                        <div class="layui-input-inline">
                            <select name="data[residence]" lay-filter="city" id="city">
                                <option value="">请选择市</option>
                            </select>
                        </div>
                        <div class="layui-input-inline">
                            <select name="data[residence]" id="county">
                                <option value="">请选择县/区</option>
                            </select>
                        </div>
                    </div>


layui.use(['layer', 'form','jquery'], function () {
        var $= layui.jquery;
        var form = layui.form;
        //如果有加载页面就渲染第一个一级分类的话 就先调用一次方法
        renderSelecte($('#province')[0]);

        //监听一级分类下拉框变化
        form.on('select(province)',function(res){
            //变化就渲染第二个分类   把第一个下拉框的value传递
            renderSelecte($('#city')[0],res.value);
        });
        //监听二级分类下拉框变化
        form.on('select(city)',function(res){
            //变化就渲染第二个分类   把第一个下拉框的value传递
            renderSelecte($('#county')[0],res.value);
        });

        function renderSelecte(ele,id){
            //先判断id是否有值,这里是为了第一个下拉框改变值的时候 好把第二个下拉框的选项都删掉
            if(id){
                ele.length=0;
            }

            var areaData = '';
            $.ajax({
                url: "",//要进行查询的地址
                type: "GET",
                dataType: "json",
                async:false,
                success: function(data){
                    areaData = data;
                }});

            areaData.forEach((item,index)=>{
                var option =new Option(item.name,item.id);
                ele.append(option);
            });
            //渲染一下表单
            form.render();
        }
    });