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

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

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

            for (var link in navLinks) {
                if (Object.prototype.hasOwnProperty.call(navLinks, link)) {
                    navLinks[link].addEventListener("click", eventListener);
                }
            }
        }
    },
    ScrollSpy = function ScrollSpy() {
        var sections = document.querySelectorAll(".mw-headline");
        window.addEventListener("scroll", function() {
            var scrollPos =
                document.documentElement.scrollTop || document.body.scrollTop;

            for (var section in sections) {
                if (
                    Object.prototype.hasOwnProperty.call(sections, section) &&
                    sections[section].offsetTop <= scrollPos
                ) {
                    var 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");
                    }
                }
            }
        });
    },
    CheckToC = 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();
        }
    });
}