Spiceworks on-scroll fixed header functionality

gistfile1.txt

//Html Code

//Note: fixed position style should be in inline style.
<header class="dell-infographic"  id="app-fixed-header" style="position:fixed"></header>


//JS code
/*
* getting the fix header element
*/
var appHeader = document.querySelector('#app-fixed-header'); 

/*
* This function will  set the top value to the fixed header element based on the scroll top
*/
function adjustHeader() {
    if (appHeader.style.position == "fixed") {
        var spiceWorksHeader = document.querySelector('.sui-opt-in');
        var topVal = spiceWorksHeader.getBoundingClientRect().top + spiceWorksHeader.scrollHeight;
        if (topVal >= 0) {
            appHeader.style.top = topVal + "px";
        }
        else {
            appHeader.style.top = "0";
        }
    }
}

window.addEventListener('scroll', function () {
    adjustHeader();
});