JavaScript联动菜单实现详解

<!DOCTYPE html>
<html>
<head>
 <meta charset="utf-8">
 <meta http-equiv="X-UA-Compatible" content="IE=edge">
 <title></title>
 <link rel="stylesheet" href="">
</head>
<body>
 <h1>联动菜单</h1>
 <select id="province" onchange="ld();">
  <option value="-1">请选择</option>
  <option value="0">安徽</option>
  <option value="1">浙江</option>
 </select>
 <select id="city">
 </select>
</body>
<script>
 //定义地区数组
 var area = [
  ['安庆','黄山','合肥'],
  ['杭州','温州','宁波']
 ];
 //联动函数
 function ld(){
   var province = document.getElementById('province');//找到省对象
   var city = document.getElementById('city');//找到市对象
   var opt = '';
   //如果是请选择，就显示空，并结束函数
   if(province.value == -1){
   city.innerHTML = opt;
   return ;
   }
   for(var i = 0 ,len = area[province.value].length;i < len;i++){
   opt += '<option value="'+i+'">'+area[province.value][i]+'</option>';
   }
   city.innerHTML = opt;
 }
</script>
</html>