如何根据Jquery实现两级联动

$(function (){

$.ajax({

url:<select:link page="/tobaccoinfo.do?method=getBrandList" />,

type: "get" ,

dataType: "json" ,

success: function (result){

var str="<option value=''>全部</option>" ;

for (var i=0;i<result.length;i++){

str+= "<option value="+result[i].id+">"+result[i].name+ "</option>" ;

}

$( "#brandid" ).html(str);

}

});

$( "#brandid" ).change( function(){

var brandid=$("#brandid" ).val();

$.ajax({

url:<select:link page="/tobaccoinfo.do?method=getTobaccoName" />,

type: 'get' ,

data:{

'brandid' :brandid

dataType: 'json' ,

success: function (result){

var str="<option value=''>全部</option>" ;

for (var i=0;i<result.length;i++){

str+= "<option value="+result[i].id_+ ">"+result[i].name_+ "</option>" ;

}

$( "#tobaccoId" ).empty().html(str);

}

});

</script>

巴特西