dropdown bootstrap select code example

Example 1: bootstrap 4 dropdown

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown button
  </button>
  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
    <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>

Example 2: selectpicker dropdown in bootsttrap

<select class="selectpicker" required multiple>
  <optgroup label="Picnic">
    <option>Mustard</option>
    <option>Ketchup</option>
    <option>Relish</option>
  </optgroup>
  <optgroup label="Camping">
    <option>Tent</option>
    <option>Flashlight</option>
    <option>Toilet Paper</option>
  </optgroup>
</select>