这是Bootstrap 3内置的。 只需将此添加到您的CSS:

.dropdown:hover .dropdown-menu {
    display: block;
}

这将隐藏下拉列表和它们的插入符号，如果它们比平板电脑小。

@media (max-width: 768px) {
    .navbar ul.dropdown-menu, .navbar li.dropdown b.caret {
        display: none;
    }
}

最好的方法是用鼠标悬停来触发Bootstrap的点击事件。这样，它应该仍然保持触摸设备友好。

$('.dropdown').hover(function(){ 
  $('.dropdown-toggle', this).trigger('click'); 
});

在我看来，最好的办法是这样的:

;(function($, window, undefined) {
    // Outside the scope of the jQuery plugin to
    // keep track of all dropdowns
    var $allDropdowns = $();

    // If instantlyCloseOthers is true, then it will instantly
    // shut other nav items when a new one is hovered over
    $.fn.dropdownHover = function(options) {

        // The element we really care about
        // is the dropdown-toggle's parent
        $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) {

                // So a neighbor can't open the dropdown
                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 helps with button groups!
            $this.hover(function() {
                if(settings.instantlyCloseOthers === true)
                    $allDropdowns.removeClass('open');

                window.clearTimeout(timeout);
                $parent.addClass('open');
            });

            // Handle submenus
            $parent.find('.dropdown-submenu').each(function(){
                var $this = $(this);
                var subTimeout;
                $this.hover(function() {
                    window.clearTimeout(subTimeout);
                    $this.children('.dropdown-menu').show();

                    // Always close submenu siblings instantly
                    $this.siblings().children('.dropdown-menu').hide();
                }, function() {
                    var $submenu = $this.children('.dropdown-menu');
                    subTimeout = window.setTimeout(function() {
                        $submenu.hide();
                    }, settings.delay);
                });
            });
        });
    };

    $(document).ready(function() {
        // apply dropdownHover to all elements with the data-hover="dropdown" attribute
        $('[data-hover="dropdown"]').dropdownHover();
    });
})(jQuery, this);

样本的标记:

<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>

我们看到，除了“My Head Hurts”的答案，“Cory Price”还发现了两个问题:

问题1:单击下拉链接将打开下拉菜单。它会一直打开，除非用户点击某个地方 或者返回到它上面，创建一个尴尬的UI。 解决方案:从导航链接中删除“class”和“data-toggle”元素

这个解决方案近乎完美，但这里的问题是，当涉及到移动设备和平板电脑时，它就行不通了!

我使用了一些jQuery代码来修复这个问题..

if ($(window).width() > 769) {
    $('.dropdown-toggle').removeAttr('data-toggle');
    $('.dropdown-menu').removeAttr('style');
    $('.dropdown').removeClass('open');
}
$(window).resize(function () {
    if ($(window).width() > 769) {
        $('.dropdown-toggle').removeAttr('data-toggle');
        $('.dropdown-menu').removeAttr('style');
        $('.dropdown').removeClass('open');
    }
    else {
        $('.dropdown-toggle').attr("data-toggle", "dropdown");
    }
});

注意:这里我们假设移动设备和平板电脑的折痕从768px开始。

我希望这能有所帮助。查看链接https://jsfiddle.net/awb7gfb1/

<nav>
    <div id="menubar" class=" collapse navbar-collapse row">
        <ul id="dropdownNavbar" class="nav navbar-nav">
            <li class="dropdown">
                <button type="button" class="btn btn-primary dropbtn"><span class="glyphicon glyphicon-time"></span>
                Time Card
                <span class="caret"></span></button>
                <div class="dropdown-content">
                    <a id="showTimeCard" href="#">My Time Card</a>
                    <a href="#">Sub Menu 2</a>
                    <a href="#">Sub Menu 3</a>
                    <a href="#">Sub Menu 4</a>
                    <a href="#">Sub Menu 5</a>
                </div>
            </li>
            <li class="dropdown">
                <button type="button" class="btn btn-primary dropbtn"><span class="glyphicon glyphicon-stats"></span>
                Project
                <span class="caret"></span></button>
                <div class="dropdown-content">
                    <a href="#">Sub Menu 1</a>
                    <a href="#">Sub Menu 2</a>
                    <a href="#">Sub Menu 3</a>
                </div>
            </li>
            <li class="dropdown">
                <button type="button" class="btn btn-primary dropbtn"><span class="glyphicon glyphicon-user"></span>
                HR Links
                <span class="caret"></span></button>
                <div class="dropdown-content">
                    <a href="#">Sub Menu 1</a>
                    <a href="#">Sub Menu 2</a>
                </div>
            </li>
            <li class="dropdown">
                <button type="button" class="btn btn-primary dropbtn">
                <span class="glyphicon glyphicon-screenshot"></span>
                Leave Tracker
                <span class="caret"></span></button>
                <div class="dropdown-content">
                    <a href="#">Sub Menu 1</a>
                    <a href="#">Sub Menu 2</a>
                    <a href="#">Sub Menu 3</a>
                    <a href="#">Sub Menu 4</a>
                </div>
            </li>
            <li class="dropdown">
                <button type="button" class="btn btn-primary dropbtn">
                <span class="glyphicon glyphicon-briefcase"></span>
                Accounts
                <span class="caret"></span></button>
                <div class="dropdown-content">
                    <a href="#">Sub Menu 1</a>
                    <a href="#">Sub Menu 2</a>
                    <a href="#">Sub Menu 3</a>
                    <a href="#">Sub Menu 4</a>
                    <a href="#">Sub Menu 5</a>
                </div>
            </li>
            <li class="dropdown">
                <button type="button" class="btn btn-primary dropbtn">
                <span class="glyphicon glyphicon-headphones"></span>
                Service Desk
                <span class="caret"></span></button>
                <div class="dropdown-content">
                    <a href="#">Sub Menu 1</a>
                    <a href="#">Sub Menu 2</a>
                    <a href="#">Sub Menu 3</a>
                    <a href="#">Sub Menu 4</a>
                </div>
            </li>
            <li class="dropdown">
                <button type="button" class="btn btn-primary dropbtn">
                <span class="glyphicon glyphicon-file"></span>
                Reports
                <span class="caret"></span></button>
                <div class="dropdown-content">
                    <a href="#">Sub Menu 1</a>
                    <a href="#">Sub Menu 2</a>
                    <a href="#">Sub Menu 3</a>
                    <a href="#">Sub Menu 4</a>
                    <a href="#">Sub Menu 5</a>
                </div>
            </li>
            <li class="dropdown">
                <button type="button" class="btn btn-primary dropbtn">
                <span class="glyphicon glyphicon-cog"></span>
                Settings
                <span class="caret"></span></button>
                <div class="dropdown-content">
                    <a href="#">Sub Menu 1</a>
                    <a href="#">Sub Menu 2</a>
                    <a href="#">Sub Menu 3</a>
                </div>
            </li>
        </ul>
    </div>
</nav>

还有CSS

.dropdown {
    float: left;
    padding-right: 1px;
}

.dropbtn{
    border: 0px;
    height: 30px;
    border-radius: 0px 10px;
}
li button, .dropbtn {
    display: inline-block;
    color: white;
    text-align: center;
}

li button:hover, .dropdown:hover .dropbtn {
    background-color: #12A5F4;
}

.dropbtn.active {
    background: #12A5F4;
}

.dropdown-content {
    display: none;
    position: absolute;
    background-color: #e8f3f4;
    min-width: 100%;
    box-shadow: 0px 8px 16px 0px rgba(0, 0, 0, 0.1);
    z-index: 10;
}

.navbar-header{
    overflow: visible;
    z-index: 1;
}

.dropdown-content a {
    color: black;
    padding: 5px 10px;
    display: block;
    text-align: left;
}

.dropdown-content a:hover {
    background-color: #d8dee2
}

.dropdown:hover .dropdown-content {
    display: block;
}

#menubar{
    padding-top: 5px;
    overflow: visible;
    z-index: 10;
    padding-left: 0px;
    padding-right: 0px;
    margin: 0px;
}

#dropdownNavbar{
    margin: 0px;
}

.navbar-toggle{
    background-color: #3382d5;
}
.navbar-toggle span{
    background-color: white;
}