问题描述
在前端Bootstrap开发时，有时候会使用到Bootstrap的下拉菜单(dropdown menu)，Bootstrap提供的下拉菜单只有在点击时才会下拉展开菜单的选项，那么要实现在鼠标悬停时自动展开菜单选项应该如何处理呢？
方案一
以下是一个没有使用Javascript或者jQuery脚本和纯CSS实现的基于Bootstrap 2.0.2及以上版本的鼠标悬停时下拉菜单自动展开的功能，同时支持多级下拉菜单的自动展开，代码如下：
Style格式:
body {
padding-top: 60px;
padding-bottom: 40px;
}
.sidebar-nav {
padding: 9px 0;
}
.dropdown-menu .sub-menu {
left: 100%;
position: absolute;
top: 0;
visibility: hidden;
margin-top: -1px;
}
.dropdown-menu li:hover .sub-menu {
visibility: visible;
}
.dropdown:hover .dropdown-menu {
display: block;
}
.nav-tabs .dropdown-menu,
.nav-pills .dropdown-menu,
.navbar .dropdown-menu {
margin-top: 0;
}
.navbar .sub-menu:before {
border-bottom: 7px solid transparent;
border-left: none;
border-right: 7px solid rgba(0, 0, 0, 0.2);
border-top: 7px solid transparent;
left: -7px;
top: 10px;
}
.navbar .sub-menu:after {
border-top: 6px solid transparent;
border-left: none;
border-right: 6px solid #fff;
border-bottom: 6px solid transparent;
left: 10px;
top: 11px;
left: -6px;
}
HTML:
<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/2.3.2/css/bootstrap.min.css" rel="stylesheet" />
<div class="navbar navbar-fixed-top">
<div class="navbar-inner">
<div class="container-fluid">
<a data-target=".nav-collapse" data-toggle="collapse" class="btn btn-navbar">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</a>
<a href="#" class="brand">Project name</a>
<div class="nav-collapse">
<ul class="nav">
<li class="active"><a href="#">Home</a></li>
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
<li class="dropdown">
<a data-toggle="dropdown" class="dropdown-toggle" href="#">Dropdown <b class="caret"></b></a>
<ul class="dropdown-menu">
<li>
<a href="#">2-level Dropdown <i class="icon-arrow-right"></i></a>
<ul class="dropdown-menu sub-menu">
<li><a href="#">Action</a></li>
<li><a href="#">Another action</a></li>
<li><a href="#">Something else here</a></li>
<li class="divider"></li>
<li class="nav-header">Nav header</li>
<li><a href="#">Separated link</a></li>
<li><a href="#">One more separated link</a></li>
</ul>
</li>
<li><a href="#">Another action</a></li>
<li><a href="#">Something else here</a></li>
<li class="divider"></li>
<li class="nav-header">Nav header</li>
<li><a href="#">Separated link</a></li>
<li><a href="#">One more separated link</a></li>
</ul>
</li>
</ul>
<form action="" class="navbar-search pull-left">
<input type="text" placeholder="Search" class="search-query span2">
</form>
<ul class="nav pull-right">
<li><a href="#">Link</a></li>
<li class="divider-vertical"></li>
<li class="dropdown">
<a class="#" href="#">Menu</a>
</li>
</ul>
</div>
<!-- /.nav-collapse -->
</div>
</div>
</div>
<hr>
<ul class="nav nav-pills">
<li class="active"><a href="#">Regular link</a></li>
<li class="dropdown">
<a href="#" data-toggle="dropdown" class="dropdown-toggle">Dropdown <b class="caret"></b></a>
<ul class="dropdown-menu" id="menu1">
<li>
<a href="#">2-level Menu <i class="icon-arrow-right"></i></a>
<ul class="dropdown-menu sub-menu">
<li><a href="#">Action</a></li>
<li><a href="#">Another action</a></li>
<li><a href="#">Something else here</a></li>
<li class="divider"></li>
<li class="nav-header">Nav header</li>
<li><a href="#">Separated link</a></li>
<li><a href="#">One more separated link</a></li>
</ul>
</li>
<li><a href="#">Another action</a></li>
<li><a href="#">Something else here</a></li>
<li class="divider"></li>
<li><a href="#">Separated link</a></li>
</ul>
</li>
<li class="dropdown">
<a href="#">Menu</a>
</li>
<li class="dropdown">
<a href="#">Menu</a>
</li>
</ul>
方案二
以下是一个使用jQyery实现的下拉菜单(dropdown menu)悬停时自动展开的功能：
jQuery('ul.nav li.dropdown').hover(function() {
jQuery(this).find('.dropdown-menu').stop(true, true).delay(200).fadeIn();
}, function() {
jQuery(this).find('.dropdown-menu').stop(true, true).delay(200).fadeOut();
});
或者：
HTML:
<ul class="list-unstyled list-inline">
<li class="dropdown">
<a data-toggle="dropdown" href="#"><i class="fa fa-bars"></i> Dropdown 1</a>
<ul class="dropdown-menu">
<li><a href="">Item 1</a></li>
<li><a href="">Item 2</a></li>
<li><a href="">Item 3</a></li>
<li><a href="">Item 4</a></li>
<li><a href="">Item 5</a></li>
</ul>
</li>
<li class="dropdown">
<a data-toggle="dropdown" href="#"><i class="fa fa-user"></i> Dropdown 2</a>
<ul class="dropdown-menu">
<li><a href="">Item A</a></li>
<li><a href="">Item B</a></li>
<li><a href="">Item C</a></li>
<li><a href="">Item D</a></li>
<li><a href="">Item E</a></li>
</ul>
</li>
</ul>
jQuery:
<script>
$('.dropdown').hover(
function() {
$(this).find('.dropdown-menu').stop(true, true).delay(200).fadeIn();
},
function() {
$(this).find('.dropdown-menu').stop(true, true).delay(200).fadeOut();
}
);
$('.dropdown-menu').hover(
function() {
$(this).stop(true, true);
},
function() {
$(this).stop(true, true).delay(200).fadeOut();
}
);
</script>
方案三
这个实现方式有些取巧了，即当鼠标在下拉菜单上悬停时，使用jQuery代码触发下拉菜单的点击(click)事件，实现了鼠标悬停时自动展开下拉菜单选项的目的，如下：
$('.dropdown').hover(function(){
$('.dropdown-toggle', this).trigger('click');
});
方案四
封装一个jQuery的下拉菜单悬停展开菜单选项的插件，如下:
;(function($, window, undefined) {
var $allDropdowns = $();
$.fn.dropdownHover = function(options) {
$allDropdowns = $allDropdowns.add(this.parent());
return this.each(function() {
var $this = $(this),
$parent = $this.parent(),
defaults = {
delay: 500,
instantlyCloseOthers: true
},
data = {
delay: $(this).data('delay'),
instantlyCloseOthers: $(this).data('close-others')
},
settings = $.extend(true, {}, defaults, options, data),
timeout;
$parent.hover(function(event) {
if(!$parent.hasClass('open') && !$this.is(event.target)) {
return true;
}
if(settings.instantlyCloseOthers === true)
$allDropdowns.removeClass('open');
window.clearTimeout(timeout);
$parent.addClass('open');
}, function() {
timeout = window.setTimeout(function() {
$parent.removeClass('open');
}, settings.delay);
});
$this.hover(function() {
if(settings.instantlyCloseOthers === true)
$allDropdowns.removeClass('open');
window.clearTimeout(timeout);
$parent.addClass('open');
});
$parent.find('.dropdown-submenu').each(function(){
var $this = $(this);
var subTimeout;
$this.hover(function() {
window.clearTimeout(subTimeout);
$this.children('.dropdown-menu').show();
$this.siblings().children('.dropdown-menu').hide();
}, function() {
var $submenu = $this.children('.dropdown-menu');
subTimeout = window.setTimeout(function() {
$submenu.hide();
}, settings.delay);
});
});
});
};
$(document).ready(function() {
$('[data-hover="dropdown"]').dropdownHover();
});
})(jQuery, this);
调用示例：
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown" data-hover="dropdown" data-delay="1000" data-close-others="false">
Account <b class="caret"></b>
</a>
<ul class="dropdown-menu">
<li><a tabindex="-1" href="#">My Account</a></li>
<li class="divider"></li>
<li><a tabindex="-1" href="#">Change Email</a></li>
<li><a tabindex="-1" href="#">Change Password</a></li>
<li class="divider"></li>
<li><a tabindex="-1" href="#">Logout</a></li>
</ul>
</li>
版权声明：本作品系原创，版权归码友网所有，如未经许可，禁止任何形式转载，违者必究。
发表评论
登录用户才能发表评论， 请 登 录 或者 注册