Net/docs/api/scripts/navigation-loader.js

navigationPageText = fetch(pathToRoot + "navigation.html").then(response => response.text())

displayNavigationFromPage = () => {
    navigationPageText.then(data => {
        document.getElementById("sideMenu").innerHTML = data;
    }).then(() => {
        document.querySelectorAll(".overview > a").forEach(link => {
            link.setAttribute("href", pathToRoot + link.getAttribute("href"));
        })
    }).then(() => {
        document.querySelectorAll(".sideMenuPart").forEach(nav => {
            if (!nav.classList.contains("hidden"))
                nav.classList.add("hidden")
        })
    }).then(() => {
        revealNavigationForCurrentPage()
    })
    document.querySelectorAll('.footer a[href^="#"]').forEach(anchor => {
        anchor.addEventListener('click', function (e) {
            e.preventDefault();
            document.querySelector(this.getAttribute('href')).scrollIntoView({
                behavior: 'smooth'
            });
        });
    });
}

revealNavigationForCurrentPage = () => {
    let pageId = document.getElementById("content").attributes["pageIds"].value.toString();
    let parts = document.querySelectorAll(".sideMenuPart");
    let found = 0;
    do {
        parts.forEach(part => {
            if (part.attributes['pageId'].value.indexOf(pageId) !== -1 && found === 0) {
                found = 1;
                if (part.classList.contains("hidden")) {
                    part.classList.remove("hidden");
                    part.setAttribute('data-active', "");
                }
                revealParents(part)
            }
        });
        pageId = pageId.substring(0, pageId.lastIndexOf("/"))
    } while (pageId.indexOf("/") !== -1 && found === 0)
};
revealParents = (part) => {
    if (part.classList.contains("sideMenuPart")) {
        if (part.classList.contains("hidden"))
            part.classList.remove("hidden");
        revealParents(part.parentNode)
    }
};

/*
    This is a work-around for safari being IE of our times.
    It doesn't fire a DOMContentLoaded, presumabely because eventListener is added after it wants to do it
*/
if (document.readyState == 'loading') {
    window.addEventListener('DOMContentLoaded', () => {
        displayNavigationFromPage()
    })
} else {
    displayNavigationFromPage()
}