eBox() {
        var box = document.createElement('div');
        box.textContent = 'This is a box';
        section.appendChild(box);
      }

      createBtn.onclick = createBox;

      resetBtn.onclick = function() {
        while (section.firstChild) {
            section.removeChild(section.firstChild);
        }
        createBox();
        createBox();
        createBox();
      }
    </script>
  </body>
</html>