Alternative to a persistent scroll event listener. This fires only when the user scrolls, then stops after 250ms.

noScrollSpy.js

var timeout = null;
$(window).scroll(function () {
  if(!timeout) {
    timeout = setTimeout(function() {
      clearTimeout(timeout);
      timeout = null;
      if ($(window).scrollTop() >= $("#navTtigger").offset().top) {
        $("nav").addClass("fixed");
      } else { $("nav").removeClass("fixed"); }
    }, 250);
  }
});