JSFiddle - React, Tailwind, and code Playground

by jquery juq

HTML

<select id="province"> 
      <option>----请选择省份----</option> 
       <option>北京</option> 
       <option>上海</option> 
       <option>江苏</option> 
   </select> 
   <select class="city"> 
   <option>----请选择城市----</option> 
   </select> 
   <select class="city"> 
       <option>东城</option> 
       <option>西城</option> 
       <option>崇文</option> 
       <option>宣武</option> 
       <option>朝阳</option> 
   </select>  
   <select class="city"> 
       <option>黄浦</option> 
       <option>卢湾</option> 
       <option>徐汇</option> 
       <option>长宁</option> 
       <option>静安</option> 
   </select> 
   <select class="city"> 
       <option>南京</option> 
       <option>镇江</option> 
       <option>苏州</option> 
       <option>南通</option> 
       <option>扬州</option> 
   </select>

JavaScript

var currentShowCity=0;
$(document).ready(function(){
   $("#province").change(function(){
   $("#province option").each(function(i,o){
   if($(this).attr("selected"))
   {
  
   $(".city").hide();
   $(".city").eq(i).show();
   currentShowCity=i;
   }
   });
   });
   $("#province").change();
});
function getSelectValue(){
alert("1级="+$("#province").val());
  
$(".city").each(function(i,o){
                    
 if(i == currentShowCity){
alert("2级="+$(".city").eq(i).val());
 }
   });
}