select in bootstrap v4 dropdown

问题

I put a select in a dropdown in bootstrap v4. It works fine on desktop; however, on mobile the select options won't show. Everything I try seems to leave desktop working and mobile not. Help greatly appreciated. Thanks.

<div class="dropdown">
  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
    Dropdown
  </button>
  <div class="dropdown-menu" aria-labelledby="dropdownMenu1">
    <span class="dropdown-item" ><input type="text"/></span>
    <span class="dropdown-item" >
      <!--<span>Grid Size</span>-->
      <select class="c-select" style="width: 50%" id="gridSize">
        <option>Grid Size</option>
        <option value="1">One</option>
        <option value="2">Two</option>
        <option value="3">Three</option>
      </select>
    </span>
    <a class="dropdown-item" href="#">Something else here</a>
  </div>
</div>

回答1:

to get selected value

$('#gridSize').val();

to get selected text

$('#gridSize:selected').text();

来源：https://stackoverflow.com/questions/36856314/select-in-bootstrap-v4-dropdown