升级联动啊。这个是从数据库取出来的还是js、写好的。我这有省级联动的例子你看下。
index.html
<!DOCTYPE html><html>
<head>
<meta charset="utf-8" />
<title></title>
</head>
<body>
<div>
<select id="province" name="province" onchange="getCity(this)">
<option value="">--请选择--</option>
</select>省
<select id="city" name="city" onchange="getDistrict(this)">
<option value="">--请选择--</option>
</select>市
<select id="district" name="district">
<option value="">--请选择--</option>
</select>区/县
</div>
<script type="text/javascript" src="js/data.js" ></script>
<script type="text/javascript">
/**
* 自调用函数，页面加载所用省份数据
* @param {Object} provice 传入js中的变量proviceJson
*/
(function(provice){
// 1.禁用城市和区县乡下拉框
var city = document.getElementById("city")
var district = document.getElementById("district")
city.disabled = "disabled"
district.disabled = "disabled"
// 2.加载所有省份
for (var i = 0 i < provice.length i++) {
var provinceOption = document.createElement("option")
var provinceSelect = document.getElementById("province")
provinceOption.innerText = provice[i].name
provinceOption.value = i//循环变量i作为option的value属性值
provinceSelect.appendChild(provinceOption)
}
})(proviceJson)
/**
* 根据省份获取城市
*/
function getCity(obj) {
// 1.激活城市下拉框
var citySel = obj.nextElementSibling || obj.nextSibling
citySel.disabled = ""
// 2.清空城市下拉框上次缓存内容（查询结果）
citySel.innerHTML = ""
var cityOpt = document.createElement("option")
cityOpt.innerText = "--请选择--"
citySel.appendChild(cityOpt)
// 3.清空区县乡下拉框上次缓存内容（查询结果）
var districtSel = obj.nextElementSibling.nextElementSibling || obj.nextSibling.nextSibling
districtSel.innerHTML = ""
var cityOpt = document.createElement("option")
cityOpt.innerText = "--请选择--"
districtSel.appendChild(cityOpt)
// 4.获取所选省份下拉框value属性值
var val = obj.value
// 5.获取省份下的城市数组
var cityArr = proviceJson[val].city
for (var i = 0 i < cityArr.length i++) {
var cityOption = document.createElement("option")
var citySelect = document.getElementById("city")
cityOption.innerText = cityArr[i].name
cityOption.value = i //循环变量i作为option的value属性值
citySelect.appendChild(cityOption)
}
}
/**
* 根据城市获取区县乡
*/
function getDistrict(obj) {
// 1.激活区县乡下拉框
var districtSel = obj.nextElementSibling || obj.nextSibling
districtSel.disabled = ""
// 2.获取所选省份value属性
var proVal = (obj.previousElementSibling || obj.previousSibling).value
// 3.获取所选择城市下拉框value属性值
var cityVal = obj.value
// 4.获取省份下的城市数组
var districtArr = proviceJson[proVal].city[cityVal].districtAndCounty
for (var i = 0 i < districtArr.length i++) {
var districtOption = document.createElement("option")
var districtSelect = document.getElementById("district")
districtOption.innerText = districtArr[i]
districtOption.value = i//循环变量i作为option的value属性值
districtSelect.appendChild(districtOption)
}
}
</script>
</body>
</html>
data.js（模拟数据）
var proviceJson = [{name: "北京市",
city: [{
name: "北京市",
districtAndCounty: ["东城区", "西城区", "崇文区", "宣武区", "朝阳区", "丰台区", "石景山区", "海淀区", "门头沟区", "房山区", "通州区", "顺义区", "昌平区", "大兴区", "怀柔区", "平谷区", "密云县", "延庆县", "延庆镇"]
}]
}, {
name: "重庆市",
city: [{
name: "重庆市",
districtAndCounty: ["渝中区", "大渡口区", "江北区", "沙坪坝区", "九龙坡区", "南岸区", "北碚区", "万盛区", "双桥区", "渝北区", "巴南区", "万州区", "涪陵区", "黔江区", "长寿区", "合川市", "永川区市", "江津市", "南川市", "綦江县", "潼南县", "铜梁县", "大足县", "荣昌县", "璧山县", "垫江县", "武隆县", "丰都县", "城口县", "梁平县", "开县", "巫溪县", "巫山县", "奉节县", "云阳县", "忠县", "石柱土家族自治县", "彭水苗族土家族自治县", "酉阳土家族苗族自治县", "秀山土家族苗族自治县"]
}]
}, {
name: "河北省",
city: [{
name: "石家庄市",
districtAndCounty: ["长安区", "桥东区", "桥西区", "新华区", "裕华区", "井陉矿区", "辛集市", "藁城市", "晋州市", "新乐市", "鹿泉市", "井陉县", "微水镇", "正定县", "正定镇", "栾城县", "栾城镇", "行唐县", "龙州镇", "灵寿县", "灵寿镇", "高邑县", "高邑镇", "深泽县", "深泽镇", "赞皇县", "赞皇镇", "无极县", "无极镇", "平山县", "平山镇", "元氏县", "槐阳镇", "赵县", "赵州镇"]
}, {
name: "张家口市",
districtAndCounty: ["桥西区", "桥东区", "宣化区", "下花园区", "宣化县", "张家口市宣化区", "张北县", "张北镇", "康保县", "康保镇", "沽源县", "平定堡镇", "尚义县", "南壕堑镇", "蔚县", "蔚州镇", "阳原县", "西城镇", "怀安县", "柴沟堡镇", "万全县", "孔家庄镇", "怀来县", "沙城镇", "涿鹿县", "涿鹿镇", "赤城县", "赤城镇", "崇礼县", "西湾子镇"]
}, {
name: "承德市",
districtAndCounty: ["双桥区", "双滦区", "鹰手营子矿区", "承德县", "下板城镇", "兴隆县", "兴隆镇", "平泉县", "平泉镇", "滦平县", "滦平镇", "隆化县", "隆化镇", "丰宁满族自治县", "大阁镇", "宽城满族自治县", "宽城镇", "围场满族蒙古族自治县", "围场镇"]
}, {
name: "秦皇岛市",
districtAndCounty: ["海港区", "山海关区", "北戴河区", "昌黎县", "昌黎镇", "抚宁县", "抚宁镇", "卢龙县", "卢龙镇", "青龙满族自治县", "青龙镇"]
}]
}]
js的全名是“JavaScript”，是其中一种前端编程语言。前端即网站前台部分，运行在PC端，移动端等浏览器上展现给用户浏览的网页。前端包含很多编程语言技术（js、html、css、vue等）
J代表原济南军区，JS就代表济南军区下属的省军区系统单位。
军改之后部队公车车牌没有更换，仍在用老式。B字母代表的是北京军区，同理，S就代表沈阳军区、L就代表原兰州军区，J代表原济南军区 ，N代表原南京军区，G代表原广州军区，C代表原成都军区。BS就代表北京军区下属的省军区系统单位。
扩展资料
在马路上行走或开汽车行驶时，经常会看到与蓝底白字车牌不一样的车牌，有黑底白字的，这是使馆用车，有白底红黑字的，这是部队工作用车。
原来的空、海，都代表空军和海军，现在的新车牌，K代表的是空，H代表的是海军。
我国陆军车牌，军委总部第一位为“军”，集团军随其所在大区字头。
样式示例：军V·01236，京V为中央军委，单独一个军字就是总部，军A为总参谋部军，军B为总政治部，军C为总后勤部，军D为总装备部，军E为军事科学院，军F为国防大学，军G为国防科技大学，军R为陆军军事院校，军T为总参三部，军V为火箭军司令部（原第二炮兵司令部），军K为总后直属单位，军M为总部所属的联勤部门。
