/**
 * .js-sticky-navbar
 *   ul
 *     li Item 1
 *     li Item 2
 */

document.addEventListener('DOMContentLoaded', function() {

  var ticking = false;
  var nav = document.querySelector('.js-sticky-navbar');

  window.addEventListener('scroll', function(e) {
      if (!ticking) {
          window.requestAnimationFrame(checkScroll);
          ticking = true;
      }
  }, false);

  // checks scroll direction and shows/hides navbar accordingly
  function checkScroll() {
      var sticky = window.scrollY > 0;
      nav.classList.toggle('navbar-sticky', sticky);
      ticking = false;
  }
  checkScroll();

});