How Do I Implement Submenus in Bootstrap 3, 4, and 5?

Submenu Implementation in Bootstrap

Bootstrap 3's initial release lacked a dedicated class for submenu functionality. However, you can still implement submenus with a bit of additional CSS.

Bootstrap 5 (2023 Update)

To implement submenus, add JavaScript to prevent the closure of submenus when their parent dropdown is open:

let dropdowns = document.querySelectorAll('.dropdown-toggle')
dropdowns.forEach((dd) => {
    dd.addEventListener('click', function (e) {
        var el = this.nextElementSibling
        el.style.display = el.style.display === 'block' ? 'none' : 'block'
    })
})

Alternatively, use CSS specifically for Navbar dropdowns:

.dropdown-submenu {
  position: relative;
}

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

.navbar-nav li:hover > ul.dropdown-menu {
    display: block;
}

Bootstrap 4 (2018 Update)

Bootstrap 4 removed the .dropdown-submenu class. Instead, use CSS to achieve submenu functionality:

Navbar Submenu on Hover:

.navbar-nav li:hover > ul.dropdown-menu {
    display: block;
}
.dropdown-submenu {
    position:relative;
}
.dropdown-submenu>.dropdown-menu {
    top:0;
    left:100%;
    margin-top:-6px;
}

Bootstrap 3

Refer to this example using Bootstrap 3:

CSS:

.dropdown-submenu {
    position:relative;
}
.dropdown-submenu>.dropdown-menu {
    top:0;
    left:100%;
    margin-top:-6px;
    margin-left:-1px;
    -webkit-border-radius:0 6px 6px 6px;
    -moz-border-radius:0 6px 6px 6px;
    border-radius:0 6px 6px 6px;
}
.dropdown-submenu:hover>.dropdown-menu {
    display:block;
}

.dropdown-submenu>a:after {
    display:block;
    content:" ";
    float:right;
    width:0;
    height:0;
    border-color:transparent;
    border-style:solid;
    border-width:5px 0 5px 5px;
    border-left-color:#cccccc;
    margin-top:5px;
    margin-right:-10px;
}
.dropdown-submenu:hover>a:after {
    border-left-color:#ffffff;
}
.dropdown-submenu.pull-left {
    float:none;
}
.dropdown-submenu.pull-left>.dropdown-menu {
    left:-100%;
    margin-left:10px;
    -webkit-border-radius:6px 0 6px 6px;
    -moz-border-radius:6px 0 6px 6px;
    border-radius:6px 0 6px 6px;
}

Markup:

<ul class="nav navbar-nav">
  <li class="menu-item dropdown">
    <a href="#" class="dropdown-toggle" data-toggle="dropdown">Drop Down<b class="caret"></b></a>
    <ul class="dropdown-menu">
      <li class="menu-item dropdown dropdown-submenu">
        <a href="#" class="dropdown-toggle" data-toggle="dropdown">Level 1</a>
        <ul class="dropdown-menu">
          <li class="menu-item ">
            <a href="#">Link 1</a>
          </li>
          <li class="menu-item dropdown dropdown-submenu">
            <a href="#" class="dropdown-toggle" data-toggle="dropdown">Level 2</a>
            <ul class="dropdown-menu">
              <li>
                <a href="#">Link 3</a>
              </li>
            </ul>
          </li>
        </ul>
      </li>
    </ul>
  </li>
</ul>

The above is the detailed content of How Do I Implement Submenus in Bootstrap 3, 4, and 5?. For more information, please follow other related articles on the PHP Chinese website!