<head>
<script language="JavaScript" type="text/javascript">
//定义了城市的二维数组，里面的顺序跟省份的顺序是相同的。通过selectedIndex获得省份的下标值来得到相应的城市数组
var city=[
["北京","天津","上海","重庆"],
["南京","苏州","南通","常州"],
["福州","福安","龙岩","南平"],
["广州","潮阳","潮州","澄海"],
["兰州","白银","定西","敦煌"]
];
function getCity(){
//获得省份下拉框的对象
var sltProvince=document.form1.province;
//获得城市下拉框的对象
var sltCity=document.form1.city;
//得到对应省份的城市数组
var provinceCity=city[sltProvince.selectedIndex - 1];
//清空城市下拉框，仅留提示选项
sltCity.length=1;
//将城市数组中的值填充到城市下拉框中
for(var i=0;i<provinceCity.length;i++){
sltCity[i+1]=new Option(provinceCity[i],city[i]);}
}
</script>
</head>
<body>
<form METHOD=POST ACTION="" name="form1">
<select NAME="province" onChange="getCity()">
<option VALUE="0">请选择所在省份 </option>
<option VALUE="1">直辖市 </option>
<option VALUE="2">江苏省 </option>
<option VALUE="3">福建省 </option>
<option VALUE="4">广东省 </option>
<option VALUE="5">甘肃省 </option>
</select>
<select NAME="city">
<option VALUE="0">请选择所在城市 </option>
</select>
</form>
</body>
