​

function constant() {

  return {

    COUNTER_PLURAL_MESSAGE: " caracteres digitados - máximo ",

    COUNTER_SINGLE_MESSAGE: " caracter digitado - máximo ",

    LIMIT_MESSAGE: "Limite de caracteres atingido!"

  };

}

​

function characterCounter() {

  const max = 100;

  const container = document.getElementById('container');

  const [textArea, inputMessage] = container.children;

  const amountCharacterTyped = textArea.value.length;

  const selectMessage = () => amountCharacterTyped === 1

      ? constant().COUNTER_SINGLE_MESSAGE

      : constant().COUNTER_PLURAL_MESSAGE;

​

  if (amountCharacterTyped === 0){

    inputMessage.innerHTML = '';

  } else if (amountCharacterTyped > 0 && amountCharacterTyped < max) {

    inputMessage.innerHTML = amountCharacterTyped + selectMessage() + max;

  } else {

    inputMessage.innerHTML = constant().LIMIT_MESSAGE;

  }

}

​

function clear() {

  document.querySelector('#container p').inputMessage.innerHTML = "";

}

​

document.querySelector('textarea').addEventListener("keyup", characterCounter);

document.querySelector('textarea').addEventListener("focusout", clear);