Apply event to DatetimePicker when clicking on a date

Good afternoon, I'm using the DatetimePicker plugin and I'm trying to apply an event when a date is pressed, for example, when selecting a date automatically, an alert is generated. I have dealt with the onclick event but I can not get it to work. I attach my code:

<div class="row" id="datosCita">
    <div class="col-md-12">
      <div class="card">
        <div class="card-header">
          Rellene los siguientes datos
        </div>
        <div class="card-body">
          <div class="row"> 
            <div  id="datos">
              <select class="select2" id="listEspec">
                <option value="0">-- Seleccione una especialidad --</option>
              </select>
            </div>
            <div id="profesionales">
              <select class="select2" id="listProf">
                <option value="0">-- Seleccione un profesional --</option>
              </select>
            </div>
            <div class="input-group">
              <div class="input-group-addon">
                <i class="fa fa-calendar"></i>
              </div>
              <input class="form-control" id="date" name="date" placeholder="DD/MM/YYYY" type="text"/>
            </div>
          </div>     

        </div>
      </div>
        </div>
      </div>
    </div>
    <div class="col-md-12">
      <div class="form-footer">
        <div class="form-group">
          <div class="col-md-9 col-md-offset-3">
            <button type="submit" class="btn btn-primary">Confirmar cita</button>
            <button type="button" class="btn btn-default">Cancelar</button>
          </div>
        </div>
      </div>
    </form>
        </div>
      </div>
    </div>
  </div>
</div>

  </div>

  <script type="text/javascript" src="assets/js/vendor.js"></script>
  <script type="text/javascript" src="assets/js/app.js"></script>
   <script src='js_propio/cookies.js'></script>

<!-- Include Date Range Picker -->

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.4.1/js/bootstrap-datepicker.min.js"></script>
<script src="js/moment.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.4.1/locales/bootstrap-datepicker.es.min.js"></script>

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.4.1/css/bootstrap-datepicker3.css"/>

<script type="text/javascript">
  $(document).ready(function(){
    var date_input=$('input[name="date"]'); //our date input has the name "date"
    var container=$('.bootstrap-iso form').length>0 ? $('.bootstrap-iso form').parent() : "body";
    date_input.datepicker({
    useCurrent: false,
    format: 'dd/mm/yyyy',
    container: container,
    todayHighlight: true,
    autoclose: true,
    startDate: "today",
    language: 'es'
    })
  })
</script>
</body>

I appreciate any help. Thank you very much in advance.