代码实现
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>JS的三级联动</title>
<style>
.js-demo {
700px;
margin: 0 auto;
padding-top: 100px;
}
select {
margin-right: 50px;
}
</style>
</head>
<body>
<div class="js-demo">
省份：
<select id="province"></select>
城市：
<select id="city"></select>
区县：
<select id="county"></select>
</div>
<script>
// ===== ===== ===== 获取select元素 ===== ===== =====
// 获取下拉表单
var select_province = document.getElementById('province');
var select_city = document.getElementById('city');
var select_county = document.getElementById('county');
// ===== ===== ===== 准备三级联动的数据 ===== ===== =====
// 省份
var arr_province = [
// 省份ID, 省份名称
{ id: 110000, name: '北京市' },
{ id: 120000, name: '天津市' },
{ id: 130000, name: '河北省' },
{ id: 140000, name: '山西省' },
{ id: 150000, name: '内蒙古自治区' },
{ id: 210000, name: '辽宁省' },
{ id: 220000, name: '吉林省' },
{ id: 230000, name: '黑龙江省' },
{ id: 310000, name: '上海市' },
{ id: 320000, name: '江苏省' }
];
// 城市
var arr_city = [
// 城市ID, 城市名称, 城市所属的省份（即本级的上一级的ID）
{ id: 110000, name: '北京市', province_id: 110000 },
{ id: 120000, name: '天津市', province_id: 120000 },
{ id: 320100, name: '南京市', province_id: 320000 },
{ id: 320200, name: '无锡市', province_id: 320000 },
{ id: 320300, name: '徐州市', province_id: 320000 },
{ id: 320400, name: '常州市', province_id: 320000 },
{ id: 320500, name: '苏州市', province_id: 320000 },
{ id: 320600, name: '南通市', province_id: 320000 },
{ id: 320700, name: '连云港市', province_id: 320000 },
{ id: 320800, name: '淮安市', province_id: 320000 }
];
// 区县
var arr_county = [
// 区县ID, 区县名称, 区县所属的城市（即本级的上一级的ID）
{ id: 110101, name: '东城区', city_id: 110000 },
{ id: 110102, name: '西城区', city_id: 110000 },
{ id: 110105, name: '朝阳区', city_id: 110000 },
{ id: 110106, name: '丰台区', city_id: 110000 },
{ id: 110107, name: '石景山区', city_id: 110000 },
{ id: 110108, name: '海淀区', city_id: 110000 },
{ id: 110109, name: '门头沟区', city_id: 110000 },
{ id: 110111, name: '房山区', city_id: 110000 },
{ id: 110112, name: '通州区', city_id: 110000 },
{ id: 110113, name: '顺义区', city_id: 110000 },
{ id: 110114, name: '昌平区', city_id: 110000 },
{ id: 110115, name: '大兴区', city_id: 110000 },
{ id: 110116, name: '怀柔区', city_id: 110000 },
{ id: 110117, name: '平谷区', city_id: 110000 },
{ id: 110118, name: '密云区', city_id: 110000 },
{ id: 110119, name: '延庆区', city_id: 110000 },
{ id: 320102, name: '玄武区', city_id: 320100 },
{ id: 320104, name: '秦淮区', city_id: 320100 },
{ id: 320105, name: '建邺区', city_id: 320100 },
{ id: 320106, name: '鼓楼区', city_id: 320100 },
{ id: 320111, name: '浦口区', city_id: 320100 },
{ id: 320113, name: '栖霞区', city_id: 320100 },
{ id: 320114, name: '雨花台区', city_id: 320100 },
{ id: 320115, name: '江宁区', city_id: 320100 },
{ id: 320116, name: '六合区', city_id: 320100 },
{ id: 320117, name: '溧水区', city_id: 320100 },
{ id: 320118, name: '高淳区', city_id: 320100 },
{ id: 320117, name: '溧水区', city_id: 320100 }
];
// ===== ===== ===== 给select填充数据的操作 ===== ===== =====
// 填充province
function addDataProvince() {
var html = "<option value='0'>请选择省份</option>";
var length = arr_province.length;
for (var i = 0; i < length; i++) {
html += "<option value='" + arr_province[i].id + "'>" + arr_province[i].name + "</option>";
}
select_province.innerHTML = html;
}
// 填充city
function addDataCity(provinceId) {
var html = "<option value='0'>请选择城市</option>";
var length = arr_city.length;
for (var i = 0; i < length; i++) {
var obj = arr_city[i];
if (obj.province_id == provinceId) {
html += "<option value='" + obj.id + "'>" + obj.name + "</option>";
}
}
select_city.innerHTML = html;
}
// 填充county
function addDataCounty(cityId) {
var html = "<option value='0'>请选择区县</option>";
var length = arr_county.length;
for (var i = 0; i < length; i++) {
var obj = arr_county[i];
if (obj.city_id == cityId) {
html += "<option value='" + obj.id + "'>" + obj.name + "</option>";
}
}
select_county.innerHTML = html;
}
// ===== ===== ===== 给select绑定change事件 ===== ===== =====
// select_province绑定change事件
select_province.onchange = function () {
var provinceId = select_province.value;
addDataCity(provinceId);
};
// select_city绑定change事件
select_city.onchange = function () {
var cityId = select_city.value;
addDataCounty(cityId);
};
// select初始化数据
addDataProvince();
addDataCity(arr_province[0].id);
addDataCounty(arr_city[0].id);
/* 核心思想就是，通过监听上一级的变化获得上级的value，进而改变本级显示的列表内容。*/
</script>
</body>
</html>
效果图如下：
本文链接：https://www.cnblogs.com/connect/p/web-three-level-linkage.html