Game-Jaming/Frontend/Javascript/OverlayScrollbar.js

let instance;

document.addEventListener("DOMContentLoaded", function() {
    //The first argument are the elements to which the plugin shall be initialized
    //The second argument has to be at least a empty object or a object with your desired options
    instance = OverlayScrollbars(document.querySelectorAll('body'), { });
});

$(function() {

    var prevScrollpos = instance.scroll().position.y;
    const BackToTop = $('#return-to-top');

    instance.options("callbacks.onScroll", function(e) {

        var currentScrollPos = instance.scroll().position.y;
        if (prevScrollpos > currentScrollPos) {
            //Scroll down
            $("#header").css({"top" : "0"});
        } else {
            //Scroll up
            $("#header").css({"top" : "-50px"});
        }

        if (currentScrollPos <= 50) {
            //Scroll down
            BackToTop.fadeOut(300);
        } else {
            //Scroll up
            BackToTop.fadeIn(300);
        }

        prevScrollpos = currentScrollPos;
    });

    GoToTop = function() {
        instance.scroll({ y : "0%"  });

        $("#header").css({"top" : "0"});
        BackToTop.fadeOut(300);
    }

    // Floating button functionality
    $('#return-to-top').click(function() {
        GoToTop();
    });
});