Javascript（四）javascript实现级联菜单

//初始化所有的信息

var cityarr=new Array(3);

cityarr["广东省"]=["广州市","江门市","清远市"];

cityarr["广西省"]=["南宁市","桂林市","北海市"];

cityarr["山东省"]=["青岛市","济南市","烟台市"];

省：<select οnchange="selectcity()" id="first">

<option value="0">--请选择--</option>

<option value="广东省">广东</option>

<option value="广西省">广西</option>

<option value="山东省">山东</option>

</select>

<br /> 

市：

<select id="city">

<option>--请选择--</option>

</select>

function selectcity(){

      //

      var first=document.getElementById("first");

      var city=document.getElementById("city");

      //先清空

      city.options.length=0;      

      if(first.value==0){

            var opt=new Option("--请选择--",0);

            city.add(opt);

      }else{

         //1、获得用户选择的值

     for(var i=0;i< cityarr[first.value].length;i++){

         var opt=new Option(cityarr[first.value][i],cityarr[first.value][i]);

         city.add(opt);

     }

      }

  }