js级联

<script type="text/javascript">    //选择地址
   var cityList=new Array();
   cityList['湖北省']=['武汉市','荆州市','孝感市','襄樊市'];
   cityList['湖南省']=['长沙市','常德市','澧县市','岳阳市'];
   cityList['河南省']=['郑州市','信阳市','洛阳市','新乡市'];
 
   function allcity(){
     var provice=document.getElementById("provice");
     for(var i in cityList){
       provice.add(new Option(i,i));
     }
   }
   function changecity(){
     var provice=document.getElementById("provice").value;
     var city=document.getElementById("city");
     city.options.length=0;
     for(var i in cityList){
      if(provice==i){
        for(var j in cityList[i]){
          city.add(new Option(cityList[i][j],cityList[i][j]));
        }
      }
     }
 }
 window.onload=allcity;
</script>