const box = document.querySelector('.box');

document.addEventListener('click', function (event) {
  // If user clicks inside the element, do nothing
  if (event.target.closest('.box')) return;

  // If user clicks outside the element, hide it!
  box.classList.add('js-is-hidden');
  localStorage.setItem('boxHidden', true);
});

document.addEventListener(
  'DOMContentLoaded',
  () => {
    const isHidden = localStorage.getItem('boxHidden');
    if (isHidden) {
      box.classList.add('js-is-hidden');
    }
  },
  false
);