Create a bootstrap dropdown which occurs after press an specific key code example

Example 1: dropdown forms in bootstrap

<li class="dropdown">
         <a href="#" class="dropdown-toggle" data-toggle="dropdown">Dropdown            

         <b class="caret"></b></a>
         <ul class="dropdown-menu">
           <li><a href="#"><form role="form">
<div class="form-group">
  <label for="sel1">Select list (select one):</label>
  <select class="form-control" id="sel1">
    <option>1</option>
    <option>2</option>
    <option>3</option>
    <option>4</option>
  </select>
  <br>
  <label for="sel2">Mutiple select list (hold shift to select more than one):</label>
  <select multiple class="form-control" id="sel2">
    <option>1</option>
    <option>2</option>
    <option>3</option>
    <option>4</option>
    <option>5</option>
  </select>
</div>

Example 2: on click drop down bootstrao

<p>
  <a class="btn btn-primary" data-toggle="collapse" href="#collapseExample" role="button" aria-expanded="false" aria-controls="collapseExample">
    Link with href
  </a>
  <button class="btn btn-primary" type="button" data-toggle="collapse" data-target="#collapseExample" aria-expanded="false" aria-controls="collapseExample">
    Button with data-target
  </button>
</p>
<div class="collapse" id="collapseExample">
  <div class="card card-body">
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  </div>
</div>