const selects = document.querySelectorAll('select');
for (const select of selects) {
  select.onchange = (function (onchange) {
    return function (evt) {
      // reference to event to pass argument properly
      evt = evt || event;
      // if an existing event already existed then execute it.
      if (onchange) { onchange(evt); }
      var text = $(this).find('option:selected').text()
      var $aux = $('<select/>').append($('<option/>').text(text))
      $(this).after($aux)
      $(this).width($aux.width())
      $aux.remove()
    }
  })(select.onchange);
}