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How to implement multi-level drop-down menu jDropMenu with jQuery_jquery

WBOY
WBOYOriginal
2016-05-16 15:41:481949browse

The example in this article describes how jQuery implements the multi-level drop-down menu jDropMenu. Share it with everyone for your reference. The details are as follows:

The jQuery multi-level drop-down menu navigation introduced here - multi-level drop-down menu, the English name is DropDown Menu. Add support for corresponding handling events mouseover, mouseout and tab operations through each() traversal. This effect is one of the most common effects we usually use, and it is also a very practical JavaScript special effect. For example, the main navigation of my BlueNight theme uses this effect of multi-level drop-down menus.

The screenshot of the running effect is as follows:

The online demo address is as follows:

http://demo.jb51.net/js/2015/jquery-nlevel-down-show-jdropmenu-codes/

The specific code is as follows: 

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>jDropMenu - jQuery 多级下拉菜单插件</title>
<style type="text/css">
#top-navigation {
 margin: 10px auto 600px;
 width:960px;
 height:36px;
}
.menu {
 margin: 0;
}
.menu-item {
 position: relative;
 z-index: 2;
 float: left;
 margin-left: 3px;
 font-size: 14px;
 width: 115px;
 line-height: 36px;
 list-style-type: none;
 text-align: center;
 display: inline;
}
.menu .has-sub-menu {
 border-top: 3px solid #369;
 line-height: 33px;
}
.sub-menu .has-sub-menu {
 border-top: none;
 line-height: 36px;
 border-right: 3px solid #369;
 width: 112px;
}
.menu-item a:link, .menu-item a:visited, .menu-item a:hover {
 font-weight: bold;
 display: block;
 width: 100%;
 background-color: #3B3939;
 color: #fff;
 overflow: hidden;
}
.menu-item a:hover {
 color: #009FBC;
 background-color: #FFF;
 text-decoration: none;
}
.menu-item .sub-menu {
 display: none;
 position: absolute;
 z-index: 3;
 top: 33px;
 left: 0;
 margin: 0;
 box-shadow: 0 3px 10px #333;
 width: 115px;
}
.sub-menu li {
 margin-left: 0;
}
.sub-menu .sub-menu {
 top: 0;
 left: 115px;
 z-index: 4;
} 
</style>
</head>
<body>
<div class="header">
 <h1>jDropMenu - jQuery 多级下拉菜单插件</h1>
</div>
<div id="top-navigation"> 
<ul class="menu" id="menu-top-navigation">
 <li class="menu-item">
 <a href="#">Home</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">Frontend</a>
 <ul class="sub-menu">
 <li class="menu-item">
 <a href="#">XHTML</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS</a>
 </li>
 <li class="menu-item">
 <a href="#">HTML5</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS 3</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">JavaScript</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item has-sub-menu">
  <a href="#">YUI</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
  </li>
 </ul>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">DOM</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">Ajax</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">JSON</a>
 <ul class="sub-menu">
 <li class="menu-item">
 <a href="#">XHTML</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">HTML5</a>
 <ul class="sub-menu">
 <li class="menu-item">
 <a href="#">XHTML</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS</a>
 </li>
 <li class="menu-item">
 <a href="#">HTML5</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS 3</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">JavaScript</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item has-sub-menu">
  <a href="#">YUI</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
  </li>
 </ul>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">DOM</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">Ajax</a>
 </li>
 <li class="menu-item">
 <a href="#">JSON</a>
 </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">CSS 3</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">JavaScript</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item has-sub-menu">
  <a href="#">YUI</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
  </li>
 </ul>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">DOM</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">Ajax</a>
 </li>
 <li class="menu-item">
 <a href="#">JSON</a>
 </li>
 </ul>
 </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">PHP</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">WordPress</a>
 <ul class="sub-menu">
 <li class="menu-item">
 <a href="#">WP Themes</a>
 </li>
 <li class="menu-item">
 <a href="#">WP Plugins</a>
 </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">SEO</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">Video</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item has-sub-menu">
  <a href="#">YUI</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item has-sub-menu">
  <a href="#">YUI</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item has-sub-menu">
  <a href="#">YUI</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
  </li>
 </ul>
  </li>
 </ul>
  </li>
 </ul>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">Downloads</a>
 <ul class="sub-menu">
 <li class="menu-item">
 <a href="#">XHTML</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS</a>
 </li>
 <li class="menu-item">
 <a href="#">HTML5</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS 3</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">JavaScript</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item has-sub-menu">
  <a href="#">YUI</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
  </li>
 </ul>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">DOM</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">Ajax</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">JSON</a>
 <ul class="sub-menu">
 <li class="menu-item">
 <a href="#">XHTML</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">HTML5</a>
 <ul class="sub-menu">
 <li class="menu-item">
 <a href="#">XHTML</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS</a>
 </li>
 <li class="menu-item">
 <a href="#">HTML5</a>
 </li>
 <li class="menu-item">
 <a href="#">CSS 3</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">JavaScript</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item has-sub-menu">
  <a href="#">YUI</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
  </li>
 </ul>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">DOM</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">Ajax</a>
 </li>
 <li class="menu-item">
 <a href="#">JSON</a>
 </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">CSS 3</a>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">JavaScript</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item has-sub-menu">
  <a href="#">YUI</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
  </li>
 </ul>
 </li>
 <li class="menu-item has-sub-menu">
 <a href="#">DOM</a>
 <ul class="sub-menu">
  <li class="menu-item">
  <a href="#">jQuery</a>
  </li>
  <li class="menu-item">
  <a href="#">YUI</a>
  </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">Ajax</a>
 </li>
 <li class="menu-item">
 <a href="#">JSON</a>
 </li>
 </ul>
 </li>
 </ul>
 </li>
 <li class="menu-item">
 <a href="#">About Us</a>
 </li>
</ul>
</div>
 <script type="text/javascript" src="jquery-1.6.2.min.js"></script>
 <script type="text/javascript">
 (function($){
 $.fn.extend({
 dropMenu: function(menuItem, subMenuItem){
 var root = $(this), // 首先找到菜单（的根节点） 
 CLS_HAS_MENU = 'has-sub-menu', 
 isIE = $.browser.msie, // 是否为 IE 浏览器
 version = $.browser.version; // 浏览器的版本
 // 没有找到菜单则退出
 // root.find(':first') 都是得到 document.getElementById('top-navigation')
 if (!root[0]) {
 return false;
 }
 // 默认的菜单标签为 li 标签（选择器）
 if (!menuItem) {
 menuItem = 'li';
 }
 // 默认的子菜单标签为 ul 标签（选择器）
 if (!subMenuItem) {
 subMenuItem = 'ul';
 }
 // $(root).find(menuItem) 找到导航菜单下所有的 li 节点
 // 通过 each() 遍历添加相应的处理事件 mouseover,mouseout 和 tab 操作的支持
 $(root).find(menuItem).each(function(i, li){
 var curMenu = $(li),
 // 找到 li 下的第一个 a 标签，添加 tab 键的支持时需要用到的
 curLink = curMenu.is('a') &#63; curMenu : $(curMenu.find('a:first')), 
 // 找到当前 li 标签下的子菜单
 subMenus = $(subMenuItem, curMenu), 
 // 判断是否有子菜单节点
 hasMenu = subMenus.length >= 1, 
 // 当前 li 标签下的子菜单
 curSubMenu = null,
 // 当前子菜单的最后一项（a 标签） 
 curSubMenuLastItem = null, 
 // 显示子菜单
 show = function(){
 // show sub menu 发现 IE6 中使用 show() 方无法显示二级以下的子菜单
 // 所以很无赖的 hack 了一下
 if (!isIE || (isIE && version > 6)) {
  curSubMenu.show(200);
 }
 else {
  curSubMenu.css('display', 'block');
 }
 }, 
 // 隐藏子菜单
 hide = function(){
 // hide sub menu
 if (!isIE || (isIE && version > 6)) {
  curSubMenu.hide(150);
 }
 else {
  curSubMenu.css('display', 'none');
 }
 };
 // 只在有子菜单的时候才做相应的处理
 if (hasMenu) {
 // 无赖 WordPress 的输出没有 .has-sub-menu
 // 只要自己手动加上了
 curMenu.addClass(CLS_HAS_MENU);
 // 找到当前 li 对应的子菜单，而不是把更次级的子菜单都找到
 // 不习惯用 subMenus.get(0)
 curSubMenu = $(subMenus[0]);
 // 当前子菜单的最后一项（a 标签） 
  curSubMenuLastItem = curSubMenu.find('a:last');
 // mouse event
 curMenu.hover(show, hide);
 // key(tab key) event
 // 获得焦点是在当前 li 下的第一个A标签上处理
 curLink.focus(show);
 // 失去焦点则需要是tab让子菜单的最后一个菜单项都走过了，才关闭子菜单
 curSubMenuLastItem.blur(hide);
 }
 });
 }
 });
 $('#top-navigation').dropMenu();
})(jQuery); 
 </script> 
 <script type="text/javascript">
 (function(){
 var _gaq = _gaq || [];
 _gaq.push(['_setAccount', 'UA-4473199-1']);
 _gaq.push(['_trackPageview']);
 (function(){
  var ga = document.createElement('script');
  ga.type = 'text/javascript';
  ga.async = true;
  ga.src = ('https:' == document.location.protocol &#63; 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
  var s = document.getElementsByTagName('script')[0];
  s.parentNode.insertBefore(ga, s);
 })();
 })();
 </script>
</body>
</html>

I hope this article will be helpful to everyone’s jquery programming design.

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