JSFiddle - React, Tailwind, and code Playground

by Renatoch

HTML

<div class="form-group">
                    <label for="services">Serviço</label>
                      <select id="select"  name="services">
                        <option value="1" selected>Compra de veículo novo</option>
                        <option value="2">Revisão</option>
                        <option value="3">Reparo</option>
                        <option value="4">Diagnóstico</option>
                        <option value="5"> Troca de óleo</option>
                        <option value="6">Outros</option>
                        </select>
                     </div>

                     <div id="textarea" class="form-group">
                    <label for="exampleFormControlTextarea1">Adicione o serviço realizado </label>
                     <textarea  class="form-control" id="exampleFormControlTextarea1" rows="3"></textarea>
                      </div>

CSS

#textarea {
  display: none;
}

JavaScript

$('#select').change(function(){

        var textarea = $('#textarea');
        var select   = $(this).val();

        textarea.hide();

        if (select == '6'){
          textarea.show();
        }

     });