:
    

    
    
    

    
        //    ,       
        var prov_list = ['  ', '  ', '  ', '  ', '  '];
        //    ,      
        var city_list = [];
        city_list[0] = ['  ', '  ', '  ', '  ', '  ', '  '];
        city_list[1] = ['  ', '  ', '  ', '  ', '   ', '  '];
        city_list[2] = ['  ', '  ', '   ', '  ', '  ', '  '];
        city_list[3] = ['  ', '  ', '  ', '  ', '  ', '  '];
        city_list[4] = ['  ', '  ', '  ', '  ', '  ', '  '];


        //  select  
        var prov_select = document.getElementById('prov');
        var city_select = document.getElementById('city');

        //             
        for (var i = 0; i < prov_list.length; i ++) {
            //prov_select.innerHTML += "<option>"+prov_list[i]+"</option>"; 
        
            prov_select.add(new Option(prov_list[i], i));
        }


        //           change  
        prov_select.onchange = function(){
            //         
            var index = this.value;
            //          
            var citys = city_list[index];

            //                
            city_select.length = 0;

            //                 
            for (var i = 0; i < citys.length; i ++) {
                city_select.add(new Option(citys[i], i));
            }

        }


        //      prov_select 
        prov_select.onchange();