JQuery实现级联下拉框效果实例讲解_jquery

.car { 
 text-align:center; 
} 
.cartype{ 
 display:none; 
} 

$(document).ready(function(){ 
 //找到下拉框 
 var carnameSelect = $(".carname").children("select"); 
 var cartypeSelect = $(".cartype").children("select"); 
 
 //给下拉框注册事件 
 carnameSelect.change(function(){ 
 var carnameValue = $(this).val(); 
 if( carnameValue != ""){ 
 //carnameValue不为空的情况接着判断 
 if(!carnameSelect.data(carnameValue)){ 
 //不在缓冲区中,需要向服务器请求 
 $.post("ChainSelect",{keyword:carnameValue,type:"top"},function(data){ 
 if (data.length != 0){ 
 //返回的数据不为空 
 cartypeSelect.html(""); 
 $("请选择汽车类型").appendTo(cartypeSelect); 
 for(var i = 0;i < data.length; i++ ){ 
 $(" "+ data[i] +"").appendTo(cartypeSelect); 
 } 
 cartypeSelect.parent().show(); 
 carnameSelect.next().show(); 
 }else{ 
 //返回的数据为空 
 cartypeSelect.parent().hide(); 
 carnameSelect.next().hide(); 
 } 
 carnameSelect.data(carnameValue,data); 
 },"json"); 
 }else{ 
 //在缓冲区中 
 var data = carnameSelect.data(carnameValue); 
 if (data.length != 0){ 
 //返回的数据不为空 
 cartypeSelect.html(""); 
 $("请选择汽车类型").appendTo(cartypeSelect); 
 for(var i = 0;i < data.length; i++ ){ 
 $(" "+ data[i] +"").appendTo(cartypeSelect); 
 } 
 cartypeSelect.parent().show(); 
 carnameSelect.next().show(); 
 }else{ 
 //返回的数据为空 
 cartypeSelect.parent().hide(); 
 carnameSelect.next().hide(); 
 } 
 } 
 }else{ 
 //carnameValue为空的情况，隐藏第二个下拉框 
 cartypeSelect.parent().hide(); 
 carnameSelect.next().hide(); 
 } 
 }); 
 
});