javascript 3레벨 드롭다운 선택 메뉴 레벨 object_navigation 메뉴

JavaScript：

复代码 代码如下:

HTML:

复主代码 代码如下:

< ;양식>

演示代码：

<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">제목 없는 문서<title> </title> <form> <select id="first"> </select> <select id="second"> </select> <select id="third"> </select> </form>
[Ctrl A 전체选 注:如需引入외부Js需刷新才能执行]