連動菜單---【菜鳥自娛】

**html內容**
<select id="province" name="province" οnchange="changeList()">
<option value="" >請選擇</option>
<option value="0" >北京</option>
<option value="1" >山東</option>
<option value="2" >四川</option>
</select>
<select id="city" name="city" οnchange="changeList()"></select>
**JavaScript代碼**
var arr=[["東城區","朝陽區",'海定區'],['青島市','濟南市','威海市'],['成都市','廣元市','綿陽市']]
function changeList(){
var pro=document.getElementById("province");
var i=parseInt(pro.value);
var chaneL=document.getElementById("city");
chaneL.innerHTML="";
for(var j=0;j<arr[i].length;j++){
chaneL.innerHTML+="<option>"+arr[i][j]+"</option>"
}
}