<script type="text/javascript">
var array = new Array();
array['黑龙江']=['哈尔滨市','齐齐哈尔市','鸡西市','鹤岗市'];
array['陕西']=['西安','咸阳','渭南','汉中'];
array['山东']=['济南','青岛','威海','日照'];
array['黑龙江']['哈尔滨市']=['道里区','南岗区','道外区','平房区'];
array['黑龙江']['齐齐哈尔市']=['龙沙区','建华区','铁锋区','昂昂溪区'];
array['黑龙江']['鸡西市']=['鸡冠区','恒山区','滴道区','梨树区'];
array['黑龙江']['鹤岗市']=['向阳区','工农区','南山区','兴安区'];
array['陕西']['西安']=['新城区','碑林区','莲湖区','灞桥区'];
array['陕西']['咸阳']=['三原县','礼泉县','彬县','长武县'];
array['陕西']['渭南']=['临渭区','华县','合阳县','白水县'];
array['陕西']['汉中']=['汉台区','南郑县','洋县','西乡县'];
array['山东']['济南']=['历下区','市中区','天桥区','历城区'];
array['山东']['青岛']=['市南区','市北区','四方区','黄岛区'];
array['山东']['威海']=['环翠区','文登市','荣成市','乳山市'];
array['山东']['日照']=['东港区','岚山区','五莲县'];
function displayShi(){
var sheng = document.getElementById("sheng").value;
var o_shi = document.getElementById("shi").options;
var o_xian = document.getElementById("xian").options;
o_shi.length=0;
o_xian.length=0;
for(i=0;i<array[sheng].length;i++){
o_shi.add(new Option(array[sheng][i],array[sheng][i]));
}
var first_shi = array[sheng][0];
for(i=0;i<array[sheng][first_shi].length;i++){ //注意这里不能写成array[sheng][0].length
o_xian.add(new Option(array[sheng][first_shi][i],array[sheng][first_shi][i]));
}
}
function displayXian(){
var sheng = document.getElementById("sheng").value;
var shi = document.getElementById("shi").value;
var o_xian = document.getElementById("xian").options;
o_xian.length=0;
for(i=0;i<array[sheng][shi].length;i++){
o_xian.add(new Option(array[sheng][shi][i],array[sheng][shi][i]));
}
}
</script>
</head>
<body>
<select name="sheng" id="sheng" onchange="displayShi()">
<option value="">--请选择--</option>
<option value="黑龙江">黑龙江</option>
<option value="陕西">陕西</option>
<option value="山东">山东</option>
</select>
<select name="shi" id="shi" onchange="displayXian()">
<option value="">--请选择--</option>
</select>
<select name="xian" id="xian">
<option value="">--请选择--</option>
</select>
<input type="button" value="点我" onclick="test()" />
</body>