怎样让 bootstrap 的点击下拉菜单变成 :hover 后自动下拉

如题。同时还不影响读屏器识别？

---

先在bootstrap.min.js下面增加

**

* @preserve
* Project: Bootstrap Hover Dropdown
* Author: Cameron Spear
* Version: v2.0.11
* Contributors: Mattia Larentis
* Dependencies: Bootstrap's Dropdown plugin, jQuery
* Description: A simple plugin to enable Bootstrap dropdowns to active on hover and provide a nice user experience.
* License: MIT
* Homepage: http://cameronspear.com/blog/bootstrap-dropdown-on-hover-plugin/
*/
;(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) {
    // don't do anything if touch is supported
    // (plugin causes some issues on mobile)
    if('ontouchstart' in document) return this; // don't want to affect chaining

    // 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')
            },
            showEvent   = 'show.bs.dropdown',
            hideEvent   = 'hide.bs.dropdown',
            // shownEvent  = 'shown.bs.dropdown',
            // hiddenEvent = 'hidden.bs.dropdown',
            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)) {
                // stop this event, stop executing any code
                // in this callback but continue to propagate
                return true;
            }

            openDropdown(event);
        }, function () {
            timeout = window.setTimeout(function () {
                $parent.removeClass('open');
                $this.trigger(hideEvent);
            }, settings.delay);
        });

        // this helps with button groups!
        $this.hover(function (event) {
            // this helps prevent a double event from firing.
            // see https://github.com/CWSpear/bootstrap-hover-dropdown/issues/55
            if(!$parent.hasClass('open') && !$parent.is(event.target)) {
                // stop this event, stop executing any code
                // in this callback but continue to propagate
                return true;
            }

            openDropdown(event);
        });

        // 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);
            });
        });

        function openDropdown(event) {
            $allDropdowns.find(':focus').blur();

            if(settings.instantlyCloseOthers === true)
                $allDropdowns.removeClass('open');

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

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

})(jQuery, this);

然后在网页的最后加
$('.dropdown-toggle').dropdownHover();
$('a.dropdown-toggle').one('click',function(){ location.href= $(this).attr('href'); });

---

如 http://v3.bootcss.com/javascript/#dropdowns 的示例，可以添加代码在 mouseover 事件中触发下拉

打开那个页面之后用 F12 打开开发者工具，在控制台输入下面的代码

$("#drop1").on("mouseover", function() {
    if ($(this).parent().is(".open")) {
        return
    }

    $(this).dropdown("toggle")
})

然后将鼠标移到第一个 Dropdown（即 “Project Name” 后面那第1个 Dropdown，就可以看到效果。