原生javascript AJAX 三级联动的实现代码
js 三级联动的实现代码如下所示：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>js原生ajax</title>
</head>
<body>
<select name="sel1">
<option value="" >-请选择 省/直辖市/自治区-</option>
</select>
<select name="sel2">
<option value="" >-请选择 市-</option>
</select>
<input type="text" value="" id="int"/>
<script>
var sel1 = document.getElementsByName('sel1')[0];
var sel2 = document.getElementsByName('sel2')[0];
var ints = document.getElementById('int');
// 创建请求对象
var a = new XMLHttpRequest();
// 初始化
a.open('get','city.json','true');
// 发送
a.send();
//readySate 状态码 交互进行到了哪一步
//0：请求未初始化
//1：服务器链接已建立
//2：请求已经接受
//3：请求处理中
//4：请求已经完成，且响应已就绪
//status 交互是否成功
a.onreadystatechange = function(){
if(a.status ==200||a.status == 304){
if(a.readyState == 4){
var obj = JSON.parse(a.response);//responseText:获得字符串形式的响应数据。
var b = obj.城市代码;
for(var i = 0;i<b.length;i++){
var nOpt = document.createElement('option');
var nOpt_t =document.createTextNode(b[i].省);
nOpt.appendChild(nOpt_t);
sel1.appendChild(nOpt);
nOpt.value = i;
console.log(ints.value)
}
sel1.onchange = function (){
var index = sel1.selectedIndex; //获取select选择的option的下标值
var va = sel1.options[index].value//获取select第几个option的value值
var city = b[va].市; //获取他下边的市
sel2.options.length = 1; //清空所有的select下的option的值
for(var i = 0;i<city.length;i++){
var nOpt = document.createElement('option');
var nOpt_t =document.createTextNode(city[i].市名);
nOpt.appendChild(nOpt_t);
sel2.appendChild(nOpt);
nOpt.value = i;
ints.value = "";
}
}
sel2.onchange = function (){
var sel1v = sel1.value;
var sel2v = sel2.value;
var intsi = b[sel1v]['市'][sel2v]['编码'];
ints.value = intsi;
}
}
}
}
</script>
</body>
</html>总结
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