gistfile1.txt

            let frame;
            const headerElement = document.getElementById('header');
            let headerToggled = false;

            function update(frameId,skip){


                frame = false;

                if ( headerToggled && window.pageYOffset > 100 ) {
                    headerToggled = false;
                    headerElement.classList.add('nav-bar');
                    console.log(headerToggled);
                } else if ( !headerToggled && window.pageYOffset < 100 ) {
                    headerToggled = true;
                    headerElement.classList.remove('nav-bar');
                    console.log(headerToggled);
                }
            }


            function callUpdate(){
                frame = frame || requestAnimationFrame(update);
            }

            window.addEventListener('scroll', callUpdate);