Html Bootstrap 4:导航中的多级下拉菜单

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时间:2020-08-29 14:44:03  来源:igfitidea点击:

Bootstrap 4: Multilevel Dropdown Inside Navigation

htmlcsstwitter-bootstrapbootstrap-4

提问by Retros

What's the easiest way to make a multilevel dropdown in Bootstrap 4? All the examples I managed to find on SO were either too messy or not included in nav.

在 Bootstrap 4 中制作多级下拉菜单的最简单方法是什么?我在 SO 上找到的所有示例要么太混乱,要么未包含在导航中。

I've tried just placing a dropdown inside a dropdown, but that doesn't seem like it's working. Can someone help me with this one?

我试过只是在下拉菜单中放置一个下拉菜单,但这似乎不起作用。有人可以帮我解决这个问题吗?

Here's the basic outline of my code:

这是我的代码的基本轮廓:

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwtheitroadesjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.1.1.slim.min.js" integrity="sha384-A7FZj7v+d/sdmMqp/nOQwliLvUsJfDHW+k9Omg/a/EheAdgtzNs3hpfag6Ed950n" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>

<nav class="navbar navbar-toggleable-md navbar-light bg-faded">
  <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <a class="navbar-brand" href="#">Navbar</a>
  <div class="collapse navbar-collapse" id="navbarNavDropdown">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link 1</a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="http://example.com" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Dropdown link
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>
    </ul>
  </div>
</nav>

回答by Gerhard G?tz

I use the following piece of CSS and JavaScript. It uses an extra class dropdown-submenu. I tested it with Bootstrap 4 beta.

我使用以下 CSS 和 JavaScript。它使用一个额外的类dropdown-submenu。我用 Bootstrap 4 beta 测试了它。

It supports multi level sub menus.

它支持多级子菜单。

$('.dropdown-menu a.dropdown-toggle').on('click', function(e) {
  if (!$(this).next().hasClass('show')) {
    $(this).parents('.dropdown-menu').first().find('.show').removeClass('show');
  }
  var $subMenu = $(this).next('.dropdown-menu');
  $subMenu.toggleClass('show');


  $(this).parents('li.nav-item.dropdown.show').on('hidden.bs.dropdown', function(e) {
    $('.dropdown-submenu .show').removeClass('show');
  });


  return false;
});
.dropdown-submenu {
  position: relative;
}

.dropdown-submenu a::after {
  transform: rotate(-90deg);
  position: absolute;
  right: 6px;
  top: .8em;
}

.dropdown-submenu .dropdown-menu {
  top: 0;
  left: 100%;
  margin-left: .1rem;
  margin-right: .1rem;
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous">

<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" integrity="sha384-h0AbiXch4ZDo7tp9hKZ4TsHbi047NrKGLO3SEJAg45jXxnGIfYzk4Si90RDIqNm1" crossorigin="anonymous"></script>

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNavDropdown">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="http://example.com" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Dropdown link
        </a>
        <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
          <li><a class="dropdown-item" href="#">Action</a></li>
          <li><a class="dropdown-item" href="#">Another action</a></li>
          <li class="dropdown-submenu">
            <a class="dropdown-item dropdown-toggle" href="#">Submenu</a>
            <ul class="dropdown-menu">
              <li><a class="dropdown-item" href="#">Submenu action</a></li>
              <li><a class="dropdown-item" href="#">Another submenu action</a></li>


              <li class="dropdown-submenu">
                <a class="dropdown-item dropdown-toggle" href="#">Subsubmenu</a>
                <ul class="dropdown-menu">
                  <li><a class="dropdown-item" href="#">Subsubmenu action</a></li>
                  <li><a class="dropdown-item" href="#">Another subsubmenu action</a></li>
                </ul>
              </li>
              <li class="dropdown-submenu">
                <a class="dropdown-item dropdown-toggle" href="#">Second subsubmenu</a>
                <ul class="dropdown-menu">
                  <li><a class="dropdown-item" href="#">Subsubmenu action</a></li>
                  <li><a class="dropdown-item" href="#">Another subsubmenu action</a></li>
                </ul>
              </li>



            </ul>
          </li>
        </ul>
      </li>
    </ul>
  </div>
</nav>

回答by Zim

Updated 2018

2018 年更新

Here is another variation on the Bootstrap 4.1Navbar with multi-level dropdown. This one uses minimal CSS for the submenu, and can be re-positioned as desired:

这是Bootstrap 4.1Navbar 的另一个变体,带有多级下拉菜单。这个子菜单使用最少的 CSS,并且可以根据需要重新定位:

enter image description here

在此处输入图片说明

https://www.codeply.com/go/nG6iMAmI2X

https://www.codeply.com/go/nG6iMAmI2X

.dropdown-submenu {
  position: relative;
}

.dropdown-submenu .dropdown-menu {
  top: 0;
  left: 100%;
  margin-top: -1px;
}

jQuery to control display of submenus:

jQuery 控制子菜单的显示:

$('.dropdown-submenu > a').on("click", function(e) {
    var submenu = $(this);
    $('.dropdown-submenu .dropdown-menu').removeClass('show');
    submenu.next('.dropdown-menu').addClass('show');
    e.stopPropagation();
});

$('.dropdown').on("hidden.bs.dropdown", function() {
    // hide any open menus when parent closes
    $('.dropdown-menu.show').removeClass('show');
});


See this answer for activating the Bootstrap 4 submenus on hover

请参阅此答案以在悬停时激活Bootstrap 4 子菜单

回答by Soheil Pourbafrani

The following is MultiLevel dropdown based on bootstrap4. I tried it was according to the bootstrap4 basic dropdown.

以下是基于 bootstrap4 的 MultiLevel 下拉菜单。我是根据 bootstrap4 基本下拉菜单尝试的。

.dropdown-submenu{
    position: relative;
}
.dropdown-submenu a::after{
    transform: rotate(-90deg);
    position: absolute;
    right: 3px;
    top: 40%;
}
.dropdown-submenu:hover .dropdown-menu, .dropdown-submenu:focus .dropdown-menu{
    display: flex;
    flex-direction: column;
    position: absolute !important;
    margin-top: -30px;
    left: 100%;
}
@media (max-width: 992px) {
    .dropdown-menu{
        width: 50%;
    }
    .dropdown-menu .dropdown-submenu{
        width: auto;
    }
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwtheitroadesjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.1.1.slim.min.js" integrity="sha384-A7FZj7v+d/sdmMqp/nOQwliLvUsJfDHW+k9Omg/a/EheAdgtzNs3hpfag6Ed950n" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>

<nav class="navbar navbar-toggleable-md navbar-light bg-faded">
  <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <a class="navbar-brand" href="#">Navbar</a>
  <div class="collapse navbar-collapse" id="navbarNavDropdown">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link 1</a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="http://example.com" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Dropdown link
        </a>
        <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
          <li><a class="dropdown-item" href="#">Action</a></li>
          <li><a class="dropdown-item" href="#">Another action</a></li>
          <li class="dropdown-submenu"><a class="dropdown-item dropdown-toggle" data-toggle="dropdown" href="#">Something else here</a>
            <ul class="dropdown-menu">
              <a class="dropdown-item" href="#">A</a>
              <a class="dropdown-item" href="#">b</a>
            </ul>
          </li>
        </ul>
      </li>
    </ul>
  </div>
</nav>

回答by Дтдця

I found this multidrop-down menuwhich work great in all device.

我发现这个多下拉菜单适用于所有设备。

Also, have hover style

另外,有悬停风格

It supports multi-level submenus with bootstrap 4.

它支持带有 bootstrap 4 的多级子菜单。

$( document ).ready( function () {
    $( '.navbar a.dropdown-toggle' ).on( 'click', function ( e ) {
        var $el = $( this );
        var $parent = $( this ).offsetParent( ".dropdown-menu" );
        $( this ).parent( "li" ).toggleClass( 'show' );

        if ( !$parent.parent().hasClass( 'navbar-nav' ) ) {
            $el.next().css( { "top": $el[0].offsetTop, "left": $parent.outerWidth() - 4 } );
        }
        $( '.navbar-nav li.show' ).not( $( this ).parents( "li" ) ).removeClass( "show" );
        return false;
    } );
} );
.navbar-light .navbar-nav .nav-link {
    color: rgb(64, 64, 64);
}
.btco-menu li > a {
    padding: 10px 15px;
    color: #000;
}

.btco-menu .active a:focus,
.btco-menu li a:focus ,
.navbar > .show > a:focus{
    background: transparent;
    outline: 0;
}

.dropdown-menu .show > .dropdown-toggle::after{
    transform: rotate(-90deg);
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" integrity="sha384-rwtheitroadesjU2yc3z8GV/NPeZWAv56rSmLldC3R/AZzGRnGxQQKnKkoFVhFQhNUwEyJ" crossorigin="anonymous">

<script src="https://code.jquery.com/jquery-3.1.1.slim.min.js" integrity="sha384-A7FZj7v+d/sdmMqp/nOQwliLvUsJfDHW+k9Omg/a/EheAdgtzNs3hpfag6Ed950n" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.min.js" integrity="sha384-DztdAPBWPRXSA/3eYEEUWrWCy7G5KFbe8fFjk5JAIxUYHKkDx6Qin1DkWx51bBrb" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/js/bootstrap.min.js" integrity="sha384-vBWWzlZJ8ea9aCX4pEW3rVHjgjt7zpkNpZk+02D9phzyeVkE+jo0ieGizqPLForn" crossorigin="anonymous"></script>

<nav class="navbar navbar-toggleable-md navbar-light bg-faded btco-menu">
    <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
        <span class="navbar-toggler-icon"></span>
    </button>
    <a class="navbar-brand" href="#">Navbar</a>
    <div class="collapse navbar-collapse" id="navbarNavDropdown">
        <ul class="navbar-nav">
            <li class="nav-item active">
                <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
            </li>
            <li class="nav-item">
                <a class="nav-link" href="#">Features</a>
            </li>
            <li class="nav-item">
                <a class="nav-link" href="#">Pricing</a>
            </li>
            <li class="nav-item dropdown">
                <a class="nav-link dropdown-toggle" href="https://bootstrapthemes.co" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Dropdown link</a>
                <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
                    <li><a class="dropdown-item" href="#">Action</a></li>
                    <li><a class="dropdown-item" href="#">Another action</a></li>
                    <li><a class="dropdown-item dropdown-toggle" href="#">Submenu</a>
                        <ul class="dropdown-menu">
                            <li><a class="dropdown-item" href="#">Submenu action</a></li>
                            <li><a class="dropdown-item" href="#">Another submenu action</a></li>

                            <li><a class="dropdown-item dropdown-toggle" href="#">Subsubmenu</a>
                                <ul class="dropdown-menu">
                                    <li><a class="dropdown-item" href="#">Subsubmenu action</a></li>
                                    <li><a class="dropdown-item" href="#">Another subsubmenu action</a></li>
                                </ul>
                            </li>
                            <li><a class="dropdown-item dropdown-toggle" href="#">Second subsubmenu</a>
                                <ul class="dropdown-menu">
                                    <li><a class="dropdown-item" href="#">Subsubmenu action</a></li>
                                    <li><a class="dropdown-item" href="#">Another subsubmenu action</a></li>
                                </ul>
                            </li>
                        </ul>
                    </li>
                </ul>
            </li>
        </ul>
    </div>
</nav>

回答by Yunhai

This one works on Bootstrap 4.3.1.

这个适用于Bootstrap 4.3.1

Jsfiddle: https://jsfiddle.net/ko6L31w4/1/

jsfiddle:https://jsfiddle.net/ko6L31w4/1/

The HTML code might be a little bit messy because I create a slightly complex dropdown menu for comprehensive test, otherwise everything is pretty straight forward.

HTML 代码可能有点乱,因为我为综合测试创建了一个稍微复杂的下拉菜单,否则一切都非常简单。

Js includes fewer ways to collapse opened dropdowns and CSS only includes minimal styles for full functionalities.

Js 包含的折叠打开的下拉列表的方法较少,而 CSS 仅包含完整功能的最小样式。

$(function() {
  $("ul.dropdown-menu [data-toggle='dropdown']").on("click", function(event) {
    event.preventDefault();
    event.stopPropagation();
    
    //method 1: remove show from sibilings and their children under your first parent
    
/*   if (!$(this).next().hasClass('show')) {
        
          $(this).parents('.dropdown-menu').first().find('.show').removeClass('show');
       }  */     
     
     
    //method 2: remove show from all siblings of all your parents
    $(this).parents('.dropdown-submenu').siblings().find('.show').removeClass("show");
    
    $(this).siblings().toggleClass("show");
    
    
    //collapse all after nav is closed
    $(this).parents('li.nav-item.dropdown.show').on('hidden.bs.dropdown', function(e) {
      $('.dropdown-submenu .show').removeClass("show");
    });

  });
});
.dropdown-submenu {
  position: relative;
}

.dropdown-submenu>.dropdown-menu {
  top: 0;
  left: 100%;
}
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" crossorigin="anonymous"></script>


<nav class="navbar navbar-expand-md navbar-light bg-white py-3 shadow-sm">
  <div class="container-fluid">
    <a href="#" class="navbar-brand font-weight-bold">Multilevel Dropdown</a>
    
  <button type="button" data-toggle="collapse" data-target="#navbarContent" aria-controls="navbars" aria-expanded="false" aria-label="Toggle navigation" class="navbar-toggler">
    <span class="navbar-toggler-icon"></span>
  </button>


  <div id="navbarContent" class="collapse navbar-collapse">
      <ul class="navbar-nav mr-auto">
      
        <!-- nav dropdown -->
        <li class="nav-item dropdown">
        
          <a href="#" data-toggle="dropdown" class="nav-link dropdown-toggle">Dropdown</a>
          <ul class="dropdown-menu">
            
            <li><a href="#" class="dropdown-item">Some action</a></li>
            
            <!-- lvl 1 dropdown -->
            <li class="dropdown-submenu">
              <a href="#" role="button" data-toggle="dropdown" class="dropdown-item dropdown-toggle">level 1</a>
              <ul class="dropdown-menu">
                <li><a href="#" class="dropdown-item">level 2</a></li>
                
                <!-- lvl 2 dropdown -->
                <li class="dropdown-submenu">
                  <a href="#" role="button" data-toggle="dropdown" class="dropdown-item dropdown-toggle">level 2</a>
                  <ul class="dropdown-menu">
                    <li><a href="#" class="dropdown-item">level 3</a></li>
                    
                    <!-- lvl 3 dropdown --> 
                    <li class="dropdown-submenu">
                      <a href="#" role="button" data-toggle="dropdown" class="dropdown-item dropdown-toggle">level 3</a>
                      <ul class="dropdown-menu">
                        <li><a href="#" class="dropdown-item">level 4</a></li>
                      </ul>
                    </li>
                    
                  </ul>
                </li>

                <li><a href="#" class="dropdown-item">level 2</a></li>
                <li><a href="#" class="dropdown-item">level 2</a></li>
              </ul>
            </li>
            
            <li><a href="#" class="dropdown-item">Some other action</a></li>
            
            <li class="dropdown-submenu">
              <a href="#" role="button" data-toggle="dropdown" class="dropdown-item dropdown-toggle">level 1</a>
              <ul class="dropdown-menu">
                
                <li class="dropdown-submenu">
                  <a href="#" role="button" data-toggle="dropdown" class="dropdown-item dropdown-toggle">level 2</a>
                  <ul class="dropdown-menu">
                    <li><a href="#" class="dropdown-item">level 3</a></li>
                    <li><a href="#" class="dropdown-item">level 3</a></li>
                  </ul>
                </li>
                
                <li class="dropdown-submenu">
                  <a href="#" role="button" data-toggle="dropdown" class="dropdown-item dropdown-toggle">level 2</a>
                  <ul class="dropdown-menu">
                    <li><a href="#" class="dropdown-item">level 3</a></li>
                    <li><a href="#" class="dropdown-item">level 3</a></li>
                  </ul>
                </li>

                <li><a href="#" class="dropdown-item">level 2</a></li>
                
                                <li class="dropdown-submenu">
                  <a href="#" role="button" data-toggle="dropdown" class="dropdown-item dropdown-toggle">level 2</a>
                  <ul class="dropdown-menu">
                    <li><a href="#" class="dropdown-item">level 3</a></li>
                    <li><a href="#" class="dropdown-item">level 3</a></li>
                  </ul>
                </li>
                
                <li><a href="#" class="dropdown-item">level 2</a></li>
              </ul>
            </li>  
          </ul>
        </li>

        <li class="nav-item"><a href="#" class="nav-link">About</a></li>
        <li class="nav-item"><a href="#" class="nav-link">Services</a></li>
        <li class="nav-item"><a href="#" class="nav-link">Contact</a></li>
      </ul>
    </div>
  </div>
</nav>

回答by dallaslu

Using official HTML without adding extra CSS styles and classes, it's like native support.

使用官方 HTML 而不添加额外的 CSS 样式和类,就像原生支持一样。

Just add the following code:

只需添加以下代码:

$.fn.dropdown = (function() {
    var $bsDropdown = $.fn.dropdown;
    return function(config) {
        if (typeof config === 'string' && config === 'toggle') { // dropdown toggle trigged
            $('.has-child-dropdown-show').removeClass('has-child-dropdown-show');
            $(this).closest('.dropdown').parents('.dropdown').addClass('has-child-dropdown-show');
        }
        var ret = $bsDropdown.call($(this), config);
        $(this).off('click.bs.dropdown'); // Turn off dropdown.js click event, it will call 'this.toggle()' internal
        return ret;
    }
})();

$(function() {
    $('.dropdown [data-toggle="dropdown"]').on('click', function(e) {
        $(this).dropdown('toggle');
        e.stopPropagation();
    });
    $('.dropdown').on('hide.bs.dropdown', function(e) {
        if ($(this).is('.has-child-dropdown-show')) {
            $(this).removeClass('has-child-dropdown-show');
            e.preventDefault();
        }
        e.stopPropagation();
    });
});

Dropdown of bootstrap can be easily changed to infinite level. It's a pity that they didn't do it.

引导程序的下拉菜单可以轻松更改为无限级别。很遗憾他们没有这样做。

BTW, a hover version: https://github.com/dallaslu/bootstrap-4-multi-level-dropdown

顺便说一句,悬停版本:https: //github.com/dallaslu/bootstrap-4-multi-level-dropdown

Here is a perfect demo: https://jsfiddle.net/dallaslu/adky6jvs/(works well with Bootstrap v4.4.1)

这是一个完美的演示:https: //jsfiddle.net/dallaslu/adky6jvs/(适用于 Bootstrap v4.4.1)