当我们注册一个qq的时候，会看到一个三级年月日的联动菜单，下面简单介绍。
<!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="Generator" content="EditPlus®"> <meta name="Author" content=""> <meta name="Keywords" content=""> <meta name="Description" content=""> <title>Document</title> </head> <body> <form name=form1> <select name=YYYY onchange="YYYYMM(this.value)"> <option value="">年</option> </select> <select name=MM onchange="MMDD(this.value)"> <option value="">月</option> </select> <select name=DD> <option value="">日</option> </select> </form> </body> <script language="JavaScript"> <
