JavaScript实现二级联动菜单与图片悬停放大效果

<script type="text/javascript">
var arr_province=["请选择省份/城市","北京市","上海市","天津市","河南省","山东省","河北省"];
var arr_city=[
  ["请选择城市/地区"],
  ["中关村","海淀区","朝阳区","昌平区","丰台区","大兴区"],
  ["宝坻区","浦东新区","长宁区","徐汇区","虹口区","宝山区"],
  ["和平区","河东区","河西区","塘沽区","大港区","北辰区"],
  ["郑州市","洛阳市","商丘市","开封市","安阳市","濮阳市"],
  ["济南市","青岛市","烟台市","德州市"],
  ["石家庄","菏泽市","唐山市"],
  ];
function init()
{
 var province=document.form1.province;
 province.style.width=150+"px";
 var city=document.form1.city;
 city.style.width=150+"px";
 //给province赋值高度，才能在其里面写入内容
 province.length=arr_province.length;
 for(var i=0;i<arr_province.length;i++)
 {
 province.options[i].text=arr_province[i];
 province.options[i].value=arr_province[i];
 }
 //设置默认被选中的选项
 var index=0;
 province.selectedIndex=index;
 //给city赋值高度，才能在其里面写入内容
 city.length=arr_city[index].length;
 for(var j=0;j<arr_city[index].length;j++)
 {
 city.options[j].text=arr_city[index][j];
 city.options[j].value=arr_city[index][j];
 }
 
}
function select_change(num)
{
 var city=document.form1.city;
 city.length=0;
 city.length=arr_city[num].length;
 for(var i=0; i<arr_city[num].length;i++)
 {
 city.options[i].text=arr_city[num][i];
 city.options[i].value=arr_city[num][i];
 }
}
</script>

<body onload="init()">
 <form name="form1">
 所在地区：<select name="province" onchange="select_change(this.selectedIndex)"></select>
 城市：<select name="city"></select>
 </form>
</body>

<script type="text/javascript">
function init()
{
 var img0=document.getElementById("img0");
 img0.onmouseover=function()
  {
  img0.style.width=img0.offsetWidth*1.5+"px"
  }
 img0.onmouseout=function()
  {
  img0.style.width=img0.offsetWidth/1.5+"px"
  }
}
</script>

<body onload="init()">
<img id="img0" src="images/4.jpg" />
</body>