JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery-validate/1.15.0/additional-methods.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery-validate/1.15.0/jquery.validate.js"></script>
<form method="post" action="" id="myform">
  <select name="listaopt" id="OptList">
    <option value="selecione...">selecione</option>
    <option value="option 1">option 1</option>
    <option value="option 2">option 2</option>
    <option value="option 3">option 3</option>
    <option value="option 4">option 4</option>
  </select>
  <br>
  <br>
  <input type="submit" value="enviar">
</form>

JavaScript

$('#myform').validate({
  rules: {
    listaopt: {
      required: true
    }
  }
});