function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}

async function changeNavAttach() {
    if (window.pageYOffset >= sticky) {
        navbar.classList.add("sticky");
        navbar.classList.add("ontop");
    } else {
        navbar.classList.remove("sticky");
        navbar.classList.remove("ontop");
    }
}

async function topForBottomBarProductPreview() {
    if (window.windowWidth < 1001) {
        document.getElementById("purchaseSection").style.top = (825 + document.getElementById("productPage").scrollTop) + "px";
    } else {
        document.getElementById("purchaseSection").style.top = null;
    }
}

document.getElementById("productPage").onscroll = function () {
    topForBottomBarProductPreview();
};

window.onscroll = function () {
    changeNavAttach();
};

function disableScroll() {
    window.addEventListener('DOMMouseScroll', preventDefault, false); // older FF
    window.addEventListener(wheelEvent, preventDefault, wheelOpt); // modern desktop
    window.addEventListener('touchmove', preventDefault, wheelOpt); // mobile
    window.addEventListener('keydown', preventDefaultForScrollKeys, false);
}

function enableScroll() {
    window.removeEventListener('DOMMouseScroll', preventDefault, false);
    window.removeEventListener(wheelEvent, preventDefault, wheelOpt);
    window.removeEventListener('touchmove', preventDefault, wheelOpt);
    window.removeEventListener('keydown', preventDefaultForScrollKeys, false);
}

function preventDefault(e) {
    e.preventDefault();
}

function preventDefaultForScrollKeys(e) {
    if (keys[e.keyCode]) {
        preventDefault(e);
        return false;
    }
}

function menu() {
    var x = document.getElementById("navbar");
    if (x.className.includes("responsive")) {
        x.className = x.className.replace(" responsive", "");
    } else {
        x.className += " responsive";
    }
}