效果图：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style>
select{
width: 80px;
margin: 5px;
}
</style>
<script>
// 省份数组
var provinceArr = ['上海', '江苏', '河北'];
// 城市数组
var cityArr = [
['上海市'],
['苏州市', '南京市', '扬州市'],
['石家庄', '秦皇岛', '张家口']
];
// 区域数组
var countryArr = [
[
['黄浦区', '静安区', '长宁区', '浦东区']
],
[
['虎丘区', '吴中区', '相城区', '姑苏区', '吴江区'],
['玄武区', '秦淮区', '建邺区', '鼓楼区', '浦口区'],
['邗江区', '广陵区', '江都区']
],
[
['长安区', '桥西区', '新华区', '井陉矿区'],
['海港区', '山海关区', '北戴河区', '抚宁区'],
['桥东区', '桥西区', '宣化区', '下花园区']
]
];
window.onload = function(){
var province = document.getElementById('province');
var city = document.getElementById('city');
var country = document.getElementById('country');
createOption(province, provinceArr);
province.onchange = function(){
city.length = 0;
createOption(city, cityArr[this.selectedIndex]);
city.onchange();
}
city.onchange = function(){
country.length = 0;
createOption(country, countryArr[province.selectedIndex][this.selectedIndex]);
}
province.onchange();
}
function createOption(obj, data){
for (var i = 0; i < data.length; i++) {
var newOption = new Option(data[i], data[i]);
obj.add(newOption, null);
}
}
</script>
</head>
<body>
省份<select name="" id="province"></select>
城市<select name="" id="city"></select>
区域<select name="" id="country"></select>
</body>
</html>
