bootstrap 4 header sticky code example

Example 1: sticky operations in javascript

var siteHeader = document.getElementById('siteHeader'),
    siteNav = document.getElementById('siteNav');

    window.onscroll = function() {
        if ( siteNav.offsetTop < document.documentElement.scrollTop + 26 || siteNav.offsetTop < document.body.scrollTop + 26) {
            siteHeader.setAttribute("class","sticky");
        }
        else {
            siteHeader.setAttribute("class","");
        }
    }

Example 2: css sticky navigatiojn

nav {
	position:sticky;
	top:0;
}

/*Top can be replaced with bottom, left, or right 
	depending on what you want :) */