<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
select{
100px;
float: left;
margin-right: 10px;
}
</style>
</head>
<body>
<select name="" id="may01">
<option value="0">请选择省份</option>
<option value="四川">四川</option>
<option value="云南">云南</option>
<option value="贵州">贵州</option>
</select>
<select name="" id="may02"></select>
<select name="" id="may03"></select>
<script>
var may01 = document.getElementById("may01");
var may02 = document.getElementById("may02");
var may03 = document.getElementById("may03");
may01.onchange=function(){
var val = this.value;
if(val=='四川'){
var sichuan=["成都市","绵阳市","乐山市"];
var str="<option value='0'>"+"请选择城市"+"</option>";
for(var i=0;i<sichuan.length;i++){
str+='<option value="'+sichuan[i]+'">'+sichuan[i]+'</option>'
}
may02.innerHTML=str
}
};
may02.onchange=function(){
var val=this.value;
if(val=="成都市"){
var chengdu=["青羊区","锦江区","武侯区"];
var str="<option value='0'>"+"请选择城市"+"</option>";
for(var i=0;i<chengdu.length;i++){
str+='<option value="'+chengdu[i]+'">'+chengdu[i]+'</option>'
}
may03.innerHTML=str
}else{
may03.innerHTML=""
}
}
</script>
</body>
</html>