使 Bootstrap 4 导航栏按钮始终可见并在任何屏幕尺寸上右对齐

Question

我正在使用最新的 Bootstrap 4 和 MDB 作为导航栏。

我怎样才能让这个按钮在右侧靠近汉堡图标的地方也可见？我无法仅使用 m*-auto 找到正确的解决方案。如果我在移动屏幕上正确显示，则它不会正确显示在桌面上，反之亦然。

我不想在里面放两个按钮。

<nav class="navbar navbar-expand-lg navbar-dark primary-color">
<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 ml-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="#">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="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>
    <button class="btn btn-sm align-middle btn-primary" type="button">Always visible here!</button>
</div>

Answer 1

将您的按钮作为 HTML 中的第二个项目（在导航栏中），然后向其中添加类ml-auto mr-3 order-lg-last，并ml-auto从ul元素中删除类，如下面的代码片段所示。

将按钮定位为HTML 中的第二项将使其位于切换器的前面，即它会出现在小屏幕上的切换器的左侧。

在ml-auto类（保证金左：自动）将按下按钮右边，mr-3给它3个单位的右边缘，而order-lg-last将重新排序它作为最后一个项目上有大的（屏幕lg）或更大。

这是代码片段（单击“运行代码片段”并展开到整页进行测试）：

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" 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/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>

<nav class="navbar navbar-expand-lg navbar-dark bg-dark primary-color">
    <a class="navbar-brand" href="#">Navbar</a>
    <button class="btn btn-sm align-middle btn-primary ml-auto mr-3 order-lg-last" type="button">Always visible here!</button>
    <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">
                <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="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>

要控制lg屏幕及上方按钮的右边距，您可以将mr-lg-0类添加到按钮。0意味着没有边距，即与切换器通常具有的右边距相同。

如果您希望按钮位于 toggler 的右侧，则可以使用以下代码（使用与上述相同的基本逻辑）：

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" 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/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>

<nav class="navbar navbar-expand-lg navbar-dark bg-dark primary-color">
    <a class="navbar-brand" href="#">Navbar</a>
    <button class="navbar-toggler ml-auto" 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>
    <button class="btn btn-sm align-middle btn-primary ml-3 order-lg-last" type="button">Always visible here!</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">
                <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="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>