<div class="dropdown">  <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">    Primary  </button>  <div class="dropdown-menu">    <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></div>

<div class="btn-group">  <button type="button" class="btn btn-primary">Primary</button>  <button type="button" class="btn btn-primary dropdown-toggle dropdown-toggle-split" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">    <span class="sr-only">Toggle Dropdown</span>  </button>  <div class="dropdown-menu">    <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 class="dropdown-divider"></div>    <a class="dropdown-item" href="#">Separated link</a>  </div></div>

<!-- Large button groups (default and split) --><div class="btn-group">  <button class="btn btn-secondary btn-lg dropdown-toggle" type="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">    Large button  </button>  <div class="dropdown-menu">    ...  </div></div><div class="btn-group">  <button class="btn btn-secondary btn-lg" type="button">    Large split button  </button>  <button type="button" class="btn btn-lg btn-secondary dropdown-toggle dropdown-toggle-split" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">    <span class="sr-only">Toggle Dropdown</span>  </button>  <div class="dropdown-menu">    ...  </div></div><!-- Small button groups (default and split) --><div class="btn-group">  <button class="btn btn-secondary btn-sm dropdown-toggle" type="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">    Small button  </button>  <div class="dropdown-menu">    ...  </div></div><div class="btn-group">  <button class="btn btn-secondary btn-sm" type="button">    Small split button  </button>  <button type="button" class="btn btn-sm btn-secondary dropdown-toggle dropdown-toggle-split" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">    <span class="sr-only">Toggle Dropdown</span>  </button>  <div class="dropdown-menu">    ...  </div></div>

<!-- Default dropup button --><div class="btn-group dropup">  <button type="button" class="btn btn-secondary dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">    Dropup  </button>  <div class="dropdown-menu">    <!-- Dropdown menu links -->  </div></div><!-- Split dropup button --><div class="btn-group dropup">  <button type="button" class="btn btn-secondary">    Split dropup  </button>  <button type="button" class="btn btn-secondary dropdown-toggle dropdown-toggle-split" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">    <span class="sr-only">Toggle Dropdown</span>  </button>  <div class="dropdown-menu">    <!-- Dropdown menu links -->  </div></div>