function Counter() {
  const _counter = new Map();
  return {
    count(element) {
      _counter.set(element, _counter.has(element) ? _counter.get(element) + 1 : 1);
      return _counter.get(element);
    },
    get counter() { return _counter }
  };
}

const counter = Counter();

document.querySelector(".wrapper").addEventListener("click", ({ target }) => {
  target.textContent = counter.count(target);
  console.log(counter.counter);
});

const btns = document.querySelectorAll('.btn');

function closure() {
  let count = 0;
  return function() {
    count++;
    this.innerText = count;
  }
}

btns.forEach(e => {
  e.addEventListener('click', closure());
})