hugo-PaperMod/layouts/partials/footer.html

<footer class="footer">
    {{- if .Site.Copyright }}
    <span>{{ .Site.Copyright | markdownify }}</span>
    {{- else }}
    <span>&copy; {{ now.Year }} <a href="{{ "" | absLangURL }}">{{ .Site.Title }}</a></span>
    {{- end }}
    <span>&middot;</span>
    <span>Powered by <a href="https://gohugo.io/" rel="noopener noreferrer" target="_blank">Hugo</a></span>
    <span>&middot;</span>
    <span>Theme <a href="https://git.io/hugopapermod" rel="noopener" target="_blank">PaperMod</a></span>
</footer>
<a href="#top" aria-label="go to top" title="Go to Top (Alt + G)">
    <button class="top-link" id="top-link" type="button" accesskey="g">
        <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 12 6">
            <path d="M12 6H0l6-6z" />
        </svg>
    </button>
</a>
{{- partial "extend_footer.html" . -}}
{{- $isHLJSdisabled := (.Site.Params.assets.disableHLJS | default .Params.disableHLJS ) }}
{{- if (and (in site.Params.mainSections .Type) (ne .Layout `archives`) (ne .Layout `search`) (not $isHLJSdisabled)) }}
{{- if not .Site.Params.assets.disableFingerprinting }}
{{- $highlight := slice (resources.Get "js/highlight.min.js") | resources.Concat "assets/js/highlight.js" | minify | fingerprint }}
<script defer src="{{ $highlight.Permalink }}" integrity="{{ $highlight.Data.Integrity }}"
    onload="hljs.initHighlightingOnLoad();"></script>
{{- else}}
{{- $highlight := slice (resources.Get "js/highlight.min.js") | resources.Concat "assets/js/highlight.js" | minify }}
<script defer src="{{ $highlight.Permalink }}" onload="hljs.initHighlightingOnLoad();"></script>
{{- end}}
{{- end }}
<script>
    window.onload = function () {
        if (localStorage.getItem("menu-scroll-position")) {
            document.getElementById('menu').scrollLeft = localStorage.getItem("menu-scroll-position");
        }
    }
    document.querySelectorAll('a[href^="#"]').forEach(anchor => {
        anchor.addEventListener("click", function (e) {
            e.preventDefault();
            var id = this.getAttribute("href").substr(1);
            document.querySelector(`[id='${decodeURIComponent(id)}']`).scrollIntoView({
                behavior: "smooth"
            });
            if (id === "top") {
                history.replaceState(null, null, " ");
            } else {
                history.replaceState(null, null, `#${id}`);
            }
        });
    });
    var mybutton = document.getElementById("top-link");
    window.onscroll = function () {
        if (document.body.scrollTop > 800 || document.documentElement.scrollTop > 800) {
            mybutton.style.visibility = "visible";
            mybutton.style.opacity = "1";
        } else {
            mybutton.style.visibility = "hidden";
            mybutton.style.opacity = "0";
        }
    };

    function menu_on_scroll() {
        localStorage.setItem("menu-scroll-position", document.getElementById('menu').scrollLeft);
    }

</script>
{{- if (not .Site.Params.disableThemeToggle) }}
<script>
    document.getElementById("theme-toggle").addEventListener("click", () => {
        if (document.body.className.includes("dark")) {
            document.body.classList.remove('dark');
            localStorage.setItem("pref-theme", 'light');
        } else {
            document.body.classList.add('dark');
            localStorage.setItem("pref-theme", 'dark');
        }
    })

</script>
{{- end }}