change nav color on scroll vanilla js

1$(function () {
2  $(document).scroll(function () {
3    var $nav = $(".navbar-fixed-top");
4    $nav.toggleClass('scrolled', $(this).scrollTop() > $nav.height());
5  });
6});

1var myNav = document.getElementById("nav");
2
3window.onscroll = function() {
4  "use strict";
5  if (document.body.scrollTop >= 280 || document.documentElement.scrollTop >= 280) {
6    myNav.classList.add("scroll");
7  } else {
8    myNav.classList.remove("scroll");
9  }
10};

1if (document.body.scrollTop >= 280 || document.documentElement.scrollTop >= 280) {
2