<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
    <head>
  <title>JS联动下拉框</title>
  <meta name="GENERATOR" content="Microsoft FrontPage 4.0">
  <meta name="ProgId" content="FrontPage.Editor.Document">
  <meta name="Originator" content="Microsoft Visual Studio .NET 7.1">
  <script language="javascript" >
  /*  
**    ==================================================================================================  
**    类名:CLASS_LIANDONG_YAO  
**    功能:多级连动菜单  
**    
**    作者:YAODAYIZI  

**    ==================================================================================================  
**/      
  function CLASS_LIANDONG_YAO(array)
  {
   //数组,联动的数据源
      this.array=array; 
      this.indexName='';
      this.obj='';
      //设置子SELECT
    // 参数:当前onchange的SELECT ID,要设置的SELECT ID
      this.subSelectChange=function(selectName1,selectName2)
      {
      //try
      //{
    var obj1=document.all[selectName1];
    var obj2=document.all[selectName2];
    var objName=this.toString();
    var me=this;
  
    obj1.οnchange=function()
    {
        
        me.optionChange(this.options[this.selectedIndex].value,obj2.id)
    }

      }
      //设置第一个SELECT
    // 参数:indexName指选中项,selectName指select的ID
      this.firstSelectChange=function(indexName,selectName)  
      {
      this.obj=document.all[selectName];
      this.indexName=indexName;
      this.optionChange(this.indexName,this.obj.id)

      }
  
  // indexName指选中项,selectName指select的ID
      this.optionChange=function (indexName,selectName)
      {
    var obj1=document.all[selectName];
    var me=this;
    obj1.length=0;
    obj1.options[0]=new Option("请选择",'');
    for(var i=0;i<this.array.length;i++)
    {    
    
        if(this.array[i][1]==indexName)
        {
        //alert(this.array[i][1]+" "+indexName);
      obj1.options[obj1.length]=new Option(this.array[i][2],this.array[i][0]);
        }
    }
      }
      
  }
  </script>
    </head>
    <body>
    <form name="form1" method="post">
       
      <SELECT ID="s1" NAME="s1"  >
    <OPTION selected></OPTION>
      </SELECT>
      <SELECT ID="s2" NAME="s2"  >
    <OPTION selected></OPTION>
      </SELECT>
      <SELECT ID="s3" NAME="s3">
    <OPTION selected></OPTION>
      </SELECT>
     
 
     


      <SELECT ID="x1" NAME="x1"  >
    <OPTION selected></OPTION>
      </SELECT>
      <SELECT ID="x2" NAME="x2"  >
    <OPTION selected></OPTION>
      </SELECT>
      <SELECT ID="x3" NAME="x3">
    <OPTION selected></OPTION>
      </SELECT>
      <SELECT ID="x4" NAME="x4">
    <OPTION selected></OPTION>
      </SELECT>
      <SELECT ID="x5" NAME="x5">
    <OPTION selected></OPTION>
      </SELECT>
      
  </form>
    </body>

    
    
    <script language="javascript">
    //例子1-------------------------------------------------------------
    //数据源
  var array=new Array();
  array[0]=new Array("华南地区","根目录","华南地区"); //数据格式 ID,父级ID,名称
  array[1]=new Array("华北地区","根目录","华北地区");
  array[2]=new Array("上海","华南地区","上海");
  array[3]=new Array("广东","华南地区","广东");
  array[4]=new Array("徐家汇","上海","徐家汇");
  array[5]=new Array("普托","上海","普托");    
  array[6]=new Array("广州","广东","广州");
  array[7]=new Array("湛江","广东","湛江");
  //--------------------------------------------
  //这是调用代码
  var liandong=new CLASS_LIANDONG_YAO(array) //设置数据源
  liandong.firstSelectChange("根目录","s1"); //设置第一个选择框
  liandong.subSelectChange("s1","s2"); //设置子级选择框
  liandong.subSelectChange("s2","s3");
  
  
    //例子2-------------------------------------------------------------
    //数据源    
  var array2=new Array();//数据格式 ID,父级ID,名称
  array2[0]=new Array("测试测试","根目录","测试测试"); 
  array2[1]=new Array("华北地区","根目录","华北地区");
  array2[2]=new Array("上海","测试测试","上海");
  array2[3]=new Array("广东","测试测试","广东");
  array2[4]=new Array("徐家汇","上海","徐家汇");
  array2[5]=new Array("普托","上海","普托");    
  array2[6]=new Array("广州","广东","广州");
  array2[7]=new Array("湛江","广东","湛江");
  array2[8]=new Array("不知道","湛江","不知道");
  array2[9]=new Array("5555","湛江","555");
  array2[10]=new Array("++++","不知道","++++");
  array2[11]=new Array("111","徐家汇","111");
  array2[12]=new Array("222","111","222");
  array2[13]=new Array("333","222","333");
  //--------------------------------------------
  //这是调用代码
  //设置数据源
  var liandong2=new CLASS_LIANDONG_YAO(array2);
  //设置第一个选择框
  liandong2.firstSelectChange("根目录","x1");
  //设置子选择框
  liandong2.subSelectChange("x1","x2")
  liandong2.subSelectChange("x2","x3")
  liandong2.subSelectChange("x3","x4")
  liandong2.subSelectChange("x4","x5")
    </script>
</html>

 

9:最简单的二个下拉菜单连动范例
<select οnchange='ok(this)' id=a><option>音乐<option>电影</select>
<select id=b>
</select>
<script>
function ok(objs){  //风云舞
if(objs.options[objs.selectedIndex].text=="音乐")b.outerHTML="<select id=b><option selected>音乐1<option>音乐2"
if(objs.options[objs.selectedIndex].text=="电影")b.outerHTML="<select id=b><option selected>电影1<option>电影2"
}
ok(a)
</script>