Question

我想显示Bootstrap Navbar的子菜单，因为它是默认设置。在每个导航项目下方。

但是我也想将子菜单背景缩放到浏览器窗口的整个宽度。

我尝试了多种解决方案，但找不到任何东西。

此刻，我尝试使用:before来设置背景，但这也不起作用。有什么解决办法吗？

到目前为止，这是我的代码：https://codepen.io/cray_code/pen/QXNVLK

如您所见，全角下拉菜单有一个解决方案。但是我希望它位于父菜单项下面而不是左边。

这是全宽版本的CSS。导航栏本身的HTML不变：

.navbar-full .dropdown-menu {
    position: absolute !important;
    left: 0 !important;
    right: 0 !important;
}

.navbar-full .dropdown, .navbar-full .navbar-nav .nav-item.dropdown {
    position: static !important;
}

Answer 1

如果您知道导航栏菜单项@media only screen and (min-width: 768px)，则可以使用媒体查询来执行此操作。
您还可以使用引导程序类来减少代码。将w-100应用于dropdown-menu，其父项dropdown应包括类position-static
更新：如果您无法控制菜单项，则可以使用jQuery

    $('a.nav-link').hover(function () {
      if ($(window).width() >= 768) {
        var myId = $(this).attr("id");
        if ($("#" + myId).length > 0) {
          var pos = Math.round($('#' + myId).position().left) + 12;
          $("a.dropdown-item").css('paddingLeft', pos + 'px');
        }
      }
    })

$('a.nav-link').hover(function() {
  if ($(window).width() >= 768) {
    var myId = $(this).attr("id");
    if ($("#" + myId).length > 0) {
      var pos = Math.round($('#' + myId).position().left) + 12;
      $("a.dropdown-item").css('paddingLeft', pos + 'px');
    }
  }
})

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

<!DOCTYPE html>
<html lang="en">

<head>
  <title>Bootstrap Example</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.8.1/css/all.css" integrity="sha384-50oBUHEmvpQ+1lW4y57PTFmhCaXp0ML5d60M1M7uH2+nqUivzIebhndOJK28anvf" crossorigin="anonymous">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js"></script>
</head>

<body>
  <nav class="navbar navbar-full 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="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>

    <div class="collapse navbar-collapse" id="navbarSupportedContent">
      <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</a>
        </li>
        <li class="nav-item dropdown position-static" id="parent">
          <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
            Dropdown 1
          </a>
          <div class="dropdown-menu w-100" aria-labelledby="navbarDropdown">
            <a class="dropdown-item mx-auto" href="#">Action</a>
            <a class="dropdown-item" href="#">Another action</a>
            <a class="dropdown-item" href="#">Another action</a>
            <a class="dropdown-item" href="#">Another action</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="#">Something else here</a>
          </div>
        </li>
        <li class="nav-item dropdown position-static" id="parent1">
          <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown1" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
              Dropdown 2
            </a>
          <div class="dropdown-menu w-100" aria-labelledby="navbarDropdown1">
            <a class="dropdown-item mx-auto" href="#">Hello</a>
            <a class="dropdown-item" href="#">New</a>
            <div class="dropdown-divider"></div>
            <a class="dropdown-item" href="#">Something else here</a>
          </div>
        </li>
        <li class="nav-item">
          <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
        </li>
      </ul>
      <form class="form-inline my-2 my-lg-0">
        <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
        <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
      </form>
    </div>
  </nav>
</body>

</html>

全宽下拉菜单，在导航项下方有子菜单

1 个答案: