原生js二级联动效果

//创建两个下拉列表 select标签 是下拉列表
   var sel = document.createElement("select");
   var sel1 = document.createElement("select");
   //添加到body
   document.body.appendChild(sel);
   document.body.appendChild(sel1);
//   创建一个数组
   var firstSelectArr = ["未选择","医院","学校","公司","星座"];
   var detailFirstArr = ["未选择","院长","主任","大夫","护士"];
   var detailSecondArr = ["未选择","校长","老师","学生","主任"];
   var arr2 = ["未选择","CEO","职员","主任","下属"];
   var arr3 = ["未选择","白羊座","射手座","处女座","天秤座"];
   function addChild(arr,parentN){
    //封装函数
    for(var i=0;i=0;i--){
     //删除选项
     sel1.removeChild(sel1.childNodes[i]);
    }
    
   }