1 <!doctype html>
2 <html>
3 <head>
4 <meta charset="UTF-8">
5 <title>HTML--JS 二级联动</title>
6 <script language="javascript">
7 var cities=[
8 ["山东省","青岛市","济南市","威海市"],
9 ["安徽省","合肥市","阜阳市","亳州市"],
10 ["河南省","郑州市","新乡市","洛阳市"]
11 ];
12 function show(val){
13 for(i=0;i<cities.length;i++){ //循环遍历，一维数组长度
14 if(cities[i][0]==val){ //一维数组下标为0的元素即省 与下拉菜单值比较
15 document.getElementById("city").length=1; // city 长度设为1
16 for(j=1;j<cities[i].length;j++){ //循环遍历，二维数组长度
17 document.getElementById("city").add(
18 new Option(cities[i][j])); //给city赋新cities选出的值
19
20 }
21 }
22
23 }
24 }
25 </script>
26 </head>
27 <body>
28 <form action="" method="post" name="myform">
29 地区:
30 <select name="area" onchange="show(this.value)" >
31 <option value="0">=请选择=</option>
32 <option value="山东省">山东省</option>
33 <option value="安徽省">安徽省</option>
34 <option value="河南省">河南省</option>
35 </select>
36
37 <select >
38 <option value="0">=请选择=</option> <!--此处一个长度-->
39 </select>
40 </form>
41 </body>
42 </html>