JS小例子之二级联动
联动原理
当用户点击省级的下拉选项,选择所在省,下一个下拉选项里的选项,则变成用户选择省下的所有市的信息,不会出现其它省市的信息.
省市数据
把省市数据,保存在js文件中,以json形式保存,以便读取,下面代码使用部分数据,不影响效果
var china = [
{
"p_name": "吉林省",
"p_id": "jl",
"cities": [
{
"c_name": "长春",
"c_id": "cc"
},
{
"c_name": "四平",
"c_id": "sp"
},
{
"c_name": "通化",
"c_id": "th"
},
{
"c_name": "松原",
"c_id": "sy"
}
]
},
{
"p_name": "辽宁省",
"p_id": "ln",
"cities": [
{
"c_name": "沈阳",
"c_id": "sy"
},
{
"c_name": "大连",
"c_id": "dl"
},
{
"c_name": "抚顺",
"c_id": "fs"
},
{
"c_name": "铁岭",
"c_id": "tl"
}
]
},
{
"p_name": "山东省",
"p_id": "sd",
"cities": [
{
"c_name": "济南",
"c_id": "jn"
},
{
"c_name": "青岛",
"c_id": "qd"
},
{
"c_name": "威海",
"c_id": "wh"
},
{
"c_name": "烟台",
"c_id": "yt"
}
]
},
{
"p_name": "上海市",
"p_id": "sh",
"cities": [
{
"c_name": "闵行区",
"c_id": "mh"
},
{
"c_name": "徐汇区",
"c_id": "xh"
},
{
"c_name": "黄浦区",
"c_id": "hp"
},
{
"c_name": "浦东新区",
"c_id": "pd"
}
]
}
];获取省市数据
通过js dom编程读取省市数据,把省市数据读取到对应的select选项中.
<!DOCTYPE html>
<html>
<head>
<title>二级联动</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body>
<select id="province" name="province">
<option value="none">--请选择省--</option>
</select>
<select id="city" name="city">
<option value="none">--请选择市--</option>
</select>
<!-- 载入省市数据 -->
<script type="text/javascript" src="cities.js"></script>
<script type="text/javascript" >
//获得省级下拉框对象
var province = document.getElementById("province");
//遍历省市数据,并把里面省的数据追加到option选项中
for (var i=0; i<china.length; i++) {
var option = document.createElement("option");
option.value = china[i].p_id;
option.innerHTML = china[i].p_name;
province.appendChild(option);
}
//省级下拉框发生改变事件
province.onchange = function() {
//获取当前点击对象的值
var proid = this.value;
var cities;
//遍历省市数据,把省级下点击的那一个选项的值和省市数据中的
//省级数据对比,如果相等,取出当前的市的数据
for (var i=0; i<china.length; i++) {
if (proid == china[i].p_id) {
cities = china[i].cities;
}
}
//获得市级下拉框对象
var city = document.getElementById("city");
//每次点击省级后,市级初始化,避免高级重复追加
city.innerHTML = "<option value='none'>--请选择市--</option>";
//遍历市级数据,并取出市级数据,追加到市级对象中
for (var i=0; i<cities.length; i++) {
var option = document.createElement("option");
option.innerHTML = cities[i].c_name;
option.value = cities[i].c_id;
city.appendChild(option);
}
}
</script>
</body>
</html>二级联动效果
