bootstrap4 按钮组及下拉菜单

<div class="btn-group">

<button type="button" class="btn btn-primary">

Apple</button>

<button type="button" class="btn btn-primary">

Samsung</button>

<div class="btn-group">

<button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">

Sony </button>

<div class="dropdown-menu">

<a class="dropdown-item" href="#">

Tablet</a> <a class="dropdown-item" href="#">

Smartphone</a>

</div>

</div></div>