SOURCE

$(function(){
   $(".div2").click(function(){
     alert(1);
   })
})
function xuanzhong(obj){ 	 
   var selectVal=$(obj).val();
   if(selectVal!=""){
      $(obj).css("background-color","yellow");
      $(obj).parent().css("background-color","yellow");
      $(".div2").css("background-color","white");
   }
}

<script src="https://cdn.static.runoob.com/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdn.static.runoob.com/libs/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<div class="div1">
  <div class="div2">ByStore</div>
  <div class="div3">
    <select id='select1' class="select1" onchange="xuanzhong(this)">
      <option value="">ByPeople</option>
       <option value="111"> 11111</option>
       <option value="222"> 2222</option>
    </select>
  </div>
</div>

.div1{
  display:inline-flex;
  border-radius:5px;
  border:1px solid #eee;
  background-color:white;
  
}
.div2{
  background-color: yellow;
  border-right:1px solid red;
  padding:5px;
  font-size:13px;
  cursor:pointer;
}
.div3{
  
}
.select1{
  padding:0px;
  margin:0px;
  border:none;
}
.select1:focus{
  border:none;
  outline: none;
}

select,input{
    -webkit-tap-highlight-color: rgba(0, 0, 0, 0);   }