像平时购物选择地址时一样，通过选择的省动态加载城市列表，通过选择的城市动态加载县区列表，从而可以实现省市县的三级联动，下面使用原生的JavaScript来实现这个功能：
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>三级联动测试</title>
<script src="https://www.linuxidc.com/jquery-2.1.4.min.js"></script>
<script type="text/javascript">
//用来获得option元素中selected属性为true的元素的id
function Get_Selected_Id(place){
var pro = document.getElementById(place);
var Selected_Id = pro.options[pro.selectedIndex].id;
return Selected_Id; //返回selected属性为true的元素的id
}
//改变下一个级联的option元素的内容，即加载市或县
function Get_Next_Place(This_Place_ID,Action){
var Selected_Id = Get_Selected_Id(This_Place_ID); //Selected_Id用来记录当前被选中的省或市的ID
if(Action=='Get_city') //从而可以在下一个级联中加载相应的市或县
Add_city(Selected_Id);
else if(Action=='Get_country')
Add_country(Selected_Id);
}
//用来存储省市区的数据结构
var Place_dict = {
"GuangDong":{
"GuangZhou":["PanYu","HuangPu","TianHe"],
"QingYuan":["QingCheng","YingDe","LianShan"],
"FoShan":["NanHai","ShunDe","SanShui"]
},
"ShanDong":{
"JiNan":["LiXia","ShiZhong","TianQiao"],
"QingDao":["ShiNan","HuangDao","JiaoZhou"]
},
"HuNan":{
"ChangSha":["KaiFu","YuHua","WangCheng"],
"ChenZhou":["BeiHu","SuXian","YongXian"]
}
};
//加载城市选项
function Add_city(Province_Selected_Id){
$("#city").empty();
$("#city").append("<option>City</option>");
$("#country").empty();
$("#country").append("<option>Country</option>");
//上面的两次清空与两次添加是为了保持级联的一致性
var province_dict = Place_dict[Province_Selected_Id]; //获得一个省的字典
for(city in province_dict){ //取得省的字典中的城市
//添加内容的同时在option标签中添加对应的城市ID
var text = "<option"+">"+city+"</option>";
$("#city").append(text);
console.log(text); //用来观察生成的text数据
}
}
//加载县区选项
function Add_country(City_Selected_Id){
$("#country").empty();
$("#country").append("<option>Country</option>");
//上面的清空与添加是为了保持级联的一致性
var Province_Selected_ID = Get_Selected_Id("province"); //获得被选中省的ID，从而方便在字典中加载数据
var country_list = Place_dict[Province_Selected_ID][City_Selected_Id]; //获得城市列表
for(index in country_list){
////添加内容的同时在option标签中添加对应的县区ID
var text = "<option"+" id=\'"+country_list[index]+"\'>"+country_list[index]+"</option>";
$("#country").append(text);
console.log(text); //用来观察生成的text数据
}
}
</script>
</head>
<body>
<p>您的收货地址：</p>
<select onchange="Get_Next_Place('province','Get_city')">
<option>Province</option>
<option value="GuangDong">GuangDong</option>
<option value="ShanDong">ShanDong</option>
<option value="HuNan">HuNan</option>
</select>
<select onchange="Get_Next_Place('city','Get_country')">
<option>City</option>
</select>
<select>
<option>Country</option>
</select>
<br/>
</body>
</html>
测试结果如下：
未做任何选择时：
选择时：
当然，省市县三者都是动态联动的，只要顶级的内容发生改变，所有子级的内容也会发生改变或被重置为City或Country.