mediawiki-skins-Citizen/resources/scripts/toc.js

/*
 * Citizen - ToC JS
 * https://starcitizen.tools
 *
 * Smooth scroll fallback and Scrollspy
 */

function SmoothScroll() {
    var navLinks, eventListener, link;
    if (!("scrollBehavior" in document.documentElement.style)) {
        navLinks = document.querySelectorAll("#toc a");
        eventListener = function eventListener(e) {
            e.preventDefault();
            e.target.scrollIntoView({
                behavior: "smooth"
            });
        };

        for (link in navLinks) {
            if (Object.prototype.hasOwnProperty.call(navLinks, link)) {
                navLinks[link].addEventListener("click", eventListener);
            }
        }
    }
}

function ScrollSpy() {
    var sections = document.querySelectorAll(".mw-headline");
    window.addEventListener("scroll", function() {
        var scrollPos = document.documentElement.scrollTop || document.body.scrollTop,
            sectionm id;

        for (section in sections) {
            if (
                Object.prototype.hasOwnProperty.call(sections, section) &&
                sections[section].offsetTop <= scrollPos
            ) {
                id = mw.util.escapeIdForAttribute(sections[section].id),
                    node = document.querySelector('a[href * = "'.concat(id, '"]'))
                    .parentNode,
                    active = document.querySelector(".active");

                if (active !== null) {
                    active.classList.remove("active");
                }
                if (node !== null) {
                    node.classList.add("active");
                }
            }
        }
    });
}

function CheckToC() {
    if (document.getElementById("toc")) {
        SmoothScroll();
        ScrollSpy();
    }
}

if (document.readyState !== "loading") {
    CheckToC();
} else if (document.addEventListener) {
    // All modern browsers to register DOMContentLoaded
    document.addEventListener("DOMContentLoaded", CheckToC);
} else {
    // Old IE browsers
    document.attachEvent("onreadystatechange", function() {
        if (document.readyState === "complete") {
            CheckToC();
        }
    });
}