How to display multiple value selected in dropdown

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdn.rawgit.com/harvesthq/chosen/gh-pages/chosen.jquery.min.js"></script>
<link href="https://cdn.rawgit.com/harvesthq/chosen/gh-pages/chosen.min.css" rel="stylesheet" />

<select data-placeholder="Begin typing a name to filter..." id="mulValue" multiple class="chosen-select" name="test">
  <option value=""></option>
  <option value="American Black Bear">American Black Bear</option>
  <option value="Sloth Bear">Sloth Bear</option>
  <option value="Sun Bear">Sun Bear</option>
  <option value="Polar Bear">Polar Bear</option>
  <option value="Spectacled Bear">Spectacled Bear</option>
</select>
<input onclick=show() type="submit">


<script>
  $(".chosen-select").chosen({
    no_results_text: "Oops, nothing found!"
  })

  function show() {
    var a = document.getElementById("mulValue").value;
    console.log('aaaaaa', a)
  }
</script>