本文介绍如何使用JavaScript实现具有图形渐隐效果的导航菜单栏。通过简单的HTML结构和JS交互，打造美观且交互友好的导航组件，适合前端开发者参考学习。
JS实现图形渐隐导航菜单栏
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <meta name="keywords" content=""> <style type=text/css> body { background:#799AE1; margin:0px; font:normal 12px 宋体; } table { border:0px; } td { font:normal 12px 宋体; } img { vertical-align:bottom; border:0px; } a { font:normal 12px 宋体; color:#215DC6; text-decoration:none; } a:hover { color:#428EFF } .sec_menu { border-left:1px solid white; border-right:1px solid white; border-bottom:1px solid white; overflow:hidden; background:#D6DFF7; } .menu_title { } .menu_title span { position:relative; top:2px; left:8px; color:#215DC6; font-weight:bold; } .menu_title2 { } .menu_title2 span { position:relative; top:2px; left:8px; color:#428EFF; font-weight:bold; } </style> <base target=main> </head> <body onselectstart="return false;" ondragstart="return false;" oncontextmenu="return false;"> <table cellpadding=0 cellspacing=0 width=158 align=center> <tr style="cursor:hand;"> <td height=42 valign=bottom> <img src=images/title.gif width=158 height=38> </td> </tr> </table> <table cellpadding=0 cellspacing=0 width=158 align=center> <tr style="cursor:hand;"> <td height=25 class=menu_title onmouseover=this.className='menu_title2'; onmouseout=this.className='menu_title'; background=http://images.jojoo.net/js/title_bg_hide.gif id=menuTitle1 onclick="menuChange(menu1,80,menuTitle1);"> <span>系统选项</span> </td> </tr> <tr> <td> <div class=sec_menu style="width:158px;height:80px;filter:alpha(Opacity=100);overflow:hidden;" id=menu1> <table cellpadding=0 cellspacing=0 align=center width=135 style="position:relative;top:10px;"> <tr> <td height=20> <img src=images/icon_safe.gif> 安全选项 </td> </tr> <tr> <td height=20> <img src=images/icon_recycle.gif> 垃圾邮件选项 </td> </tr> <tr> <td height=20> <img src=images/icon_dynamic.gif> 动态规则选项 </td> </tr> </table> </div> </td> </tr> </table> <table cellpadding=0 cellspacing=0 width=158 align=center> <tr style="cursor:hand;"> <td height=25 class=menu_title onmouseover=this.className='menu_title2'; onmouseout=this.className='menu_title'; background=http://images.jojoo.net/js/title_bg_show.gif id=menuTitle2 onclick="menuChange(menu2,120,menuTitle2);"> <span>系统规则</span> </td> </tr> <tr> <td> <div class=sec_menu style="width:158;height:0;filter:alpha(Opacity=0);display:none;" id=menu2> <table cellpadding=0 cellspacing=0 align=center width=135 style="position:relative;top:10px;"> <tr> <td height=20> <img src=images/icon_ip.gif> IP过滤规则 </td> </tr> <tr> <td height=20> <img src=images/icon_mailer.gif> 信封过滤规则 </td> </tr> <tr> <td height=20> <img src=images/icon_mailheader.gif> 信头过滤规则 </td> </tr> <tr> <td height=20> <img src=images/icon_mailbody.gif> 信体过滤规则 </td> </tr> <tr> <td height=20> <img src=images/icon_accessory.gif> 附件过滤规则 </td> </tr> </table> </div> </td> </tr> </table> <table cellpadding=0 cellspacing=0 width=158 align=center> <tr style="cursor:hand;"> <td height=25 class=menu_title onmouseover=this.className='menu_title2'; onmouseout=this.className='menu_title'; background=http://images.jojoo.net/js/title_bg_show.gif id=menuTitle3 onclick="menuChange(menu3,120,menuTitle3);"> <span>系统管理</span> </td> </tr> <tr> <td> <div class=sec_menu style="width:158;height:0;filter:alpha(Opacity=0);display:none;" id=menu3> <table cellpadding=0 cellspacing=0 align=center width=135 style="position:relative;top:10px;"> <tr> <td height=20> <img src=images/icon_user.gif> 用户管理 </td> </tr> <tr> <td height=20> <img src=images/icon_course.gif> 进程管理 </td> </tr> <tr> <td height=20> <img src=images/icon_host.gif> 主机运行状态 </td> </tr> <tr> <td height=20> <img src=images/icon_data.gif> 数据备份 </td> </tr> <tr> <td height=20> <img src=images/icon_recycle.gif> 垃圾目录管理 </td> </tr> </table> </div> </td> </tr> </table> <table cellpadding=0 cellspacing=0 width=158 align=center> <tr style="cursor:hand;"> <td height=25 class=menu_title onmouseover=this.className='menu_title2'; onmouseout=this.className='menu_title'; background=http://images.jojoo.net/js/title_bg_show.gif id=menuTitle4 onclick="menuChange(menu4,140,menuTitle4);"> <span>系统统计</span> </td> </tr> <tr> <td> <div class=sec_menu style="width:158;height:0;filter:alpha(Opacity=0);display:none;" id=menu4> <table cellpadding=0 cellspacing=0 align=center width=135 style="position:relative;top:10px;"> <tr> <td height=20> <img src=images/icon_ip.gif> IP过滤统计 </td> </tr> <tr> <td height=20> <img src=images/icon_mailer.gif> 信封过滤统计 </td> </tr> <tr> <td height=20> <img src=images/icon_mailheader.gif> 信头过滤统计 </td> </tr> <tr> <td height=20> <img src=images/icon_mailbody.gif> 信体过滤统计 </td> </tr> <tr> <td height=20> <img src=images/icon_accessory.gif> 附件过滤统计 </td> </tr> <tr> <td height=20> <img src=images/icon_dynamic.gif> 动态规则统计 </td> </tr> </table> </div> </td> </tr> </table> <table cellpadding=0 cellspacing=0 width=158 align=center> <tr style="cursor:hand;"> <td height=25 class=menu_title onmouseover=this.className='menu_title2'; onmouseout=this.className='menu_title'; background=http://images.jojoo.net/js/title_bg_quit.gif> <span>退出系统</span> </td> </tr> </table> </body> </html>注意：引入外部JavaScript文件后，需要刷新页面才能执行相关效果。