JS implements three-level cascade

This time I will bring you JS to implement three-level cascade. What are the precautions for JS to implement three-level cascade? The following is a practical case, let's take a look.

The example in this article shares with you the specific code for realizing three-level cascading special effects in js for your reference. The specific content is as follows

nbsp;html>

  
    <meta>
    <title></title>
  
  
<!-- 实现效果：选择省会出现相应的县下拉框，同时市的下拉框改变-->
    <script>  
    //二维数组存放市的信息
      var shi =[["丽水市","杭州市"],["新乡","郑州"]]; 
      //三维数组存放县的信息   
   var xianes = [[["云和","景宁"],["桐庐","原阳"]],[["卫辉","下乡"],["中原","二七"]]];
      //所选的省值
    var proIndex = 0;
      function sgc(){
        //获得所选择的省的下拉框值
     var pro = document.getElementById("sheng");
       //获得市的下拉框 
    var cit = document.getElementById("shi");
       //将省的value与市的一维数组下标所对应 
    proIndex = pro.value-1;
    //清空市下拉框中原有的值
        cit.options.length = 1;
        //通过for循环往下拉框中添加市的信息
        for(var i = 0;i < shi[proIndex].length;i++){
          var op = document.createElement("option");
          var citName = document.createTextNode(shi[proIndex][i]);
          op.value = i;
          op.appendChild(citName);
          cit.appendChild(op);          
        }      
      }
   //市的值改变后改变县的值
      function sic(){
        var are = document.getElementById("xian");
        var cit = document.getElementById("shi");
        are.options.length = 1;
    //通过proIndex获得所选的省的值作为县的数组的一维数组下标，通过cit.value作为县数组的二维数组下标，遍历获得数组值
        for(var i = 0;i<xianes[proIndex][cit.value].length;i++){
          var op = document.createElement("option");
          var areName = document.createTextNode(xianes[proIndex][cit.value][i]);
          op.value = i;
          op.appendChild(areName);
          are.appendChild(op);
        }
      }
    </script>
  //onchange():控件的value值改变后调用方法
    <select>
      <option>----省份---</option>
      <option>浙江省</option>
      <option>河南省</option>
    </select>
    <select>
      <option>---市区---</option>
    </select>
    <select>
      <option>---县区---</option>
    </select>
  

I believe you have mastered the method after reading the case in this article. More Please pay attention to other related articles on the php Chinese website!

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