How to make header or navigation bar sticky while scrolling - using javascript

========================= Sticky header js ===========

<script>
//<![CDATA[
//Sticky header
$(document).scroll(function(){var e=$(document).scrollTop();e>75?$(".header-header").addClass("sticky"):$(".header-header").removeClass("sticky")});
//]]>
</script>

----CSS---

.header-header.sticky{position:fixed;transition: all 0.4s ease;margin:0 auto;top:0;padding:0;border-bottom:1px solid #eee;z-index:999999;width:100%}

---