mycode

<script src = "http://code.jquery.com/jquery-latest.min.js" type = "text/javascript"></script>
<select name="tipo" id="tipo" class="form-control select2" required>
     <option></option>
     <option value="prev">Intervenção Preventiva</option>
     <option value="agenda">Intervenção Planeada</option>
 </select>
 <input id="teste" name="teste" type="number" placeholder="Nº De Repetições"
         class="form-control input-md">
         <script type="text/javascript">
              var hideAll = function () {
         $('.optiondiv1').hide();
     }
     $('#tipo').on('change', function () {
         hideAll();
         var category = $(this).val();
          $('.' + category).show();
          document.getElementById("teste").value = "teste";


     });
         </script>