const $ = (selector) => {
  const element = document.querySelector(selector);

  element.on = (event, callback) => {
    element.addEventListener(event, callback);
  };

  element.hide = function () {
    this.style.display = 'none';
  };

  element.show = function () {
    this.style.display = 'block';
  };

  return element;
}

$('#hide').on('click', function ()  {
  this.hide();
})