JavaScript二级下拉框联动_python二级联动下拉框-优快云博客

本文介绍了一个使用JavaScript实现的下拉菜单联动效果。通过一级菜单的选择来更新二级菜单的内容，展示了如何根据不同的一级菜单选项加载对应的二级菜单选项。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">

<script language="javascript">
//获取一级菜单长度
var select1_len = document.frm.s1.options.length;
var select2 = new Array(select1_len);

//把一级菜单都设为数组
for (i=0; i<select1_len; i++)
{
 select2[i] = new Array();
}

//定义基本选项
select2[0][0] = new Option("请选择", " ");

select2[1][0] = new Option("PHP", " ");
select2[1][1] = new Option("ASP", " ");
select2[1][2] = new Option("JSP", " ");

select2[2][0] = new Option("C/C++", " ");
select2[2][1] = new Option("Java", " ");
select2[2][2] = new Option("C#", " ");

select2[3][0] = new Option("Perl", " ");
select2[3][1] = new Option("Ruby", " ");
select2[3][2] = new Option("Python", " ");

//联动函数
function redirec(x)
{
 var temp = document.frm.s2; 
 for (i=0;i<select2[x].length;i++)
 {
  temp.options[i]=new Option(select2[x][i].text,select2[x][i].value);
 }
 temp.options[0].selected=true;

}

</script>
</head>
<form name="frm">
<select name="s1" onChange="redirec(document.frm.s1.options.selectedIndex)">
 <option selected>请选择</option>
 <option value="1">脚本语言</option>
 <option value="2">高级语言</option>
 <option value="3">其他语言</option>
</select> 

<select name="s2">
 <option value="请选择" selected>请选择</option>
</select>
</form><span style="font-family: Arial, Helvetica, sans-serif;"></html></span>

效果如下：