peter
c91caffa5e
Replace ~48 magic z-index values (z-10..z-[9999] + 2 inline zIndex) with named tailwind zIndex tokens (base/menu/chrome/paneltab/panel/rail/overlay/popover/ tooltip/tuner). Values are UNCHANGED — a rename, not a renumber — so layering is identical; the names give one source of truth for the stack.
61 lines
3.2 KiB
TypeScript
61 lines
3.2 KiB
TypeScript
import { useEffect, useRef, useState } from "react";
|
|
import { createPortal } from "react-dom";
|
|
import { ArrowUp } from "lucide-react";
|
|
import { useTranslation } from "react-i18next";
|
|
|
|
// A floating "back to top" button that fades in once the current page's scroll container is
|
|
// scrolled past a threshold, and smooth-scrolls it back to the top. Every page scrolls inside a
|
|
// <main class="overflow-y-auto"> — the normal pages share App's, the channel page renders its own
|
|
// — so this follows whichever one is mounted. Portaled to <body> so its fixed position is
|
|
// viewport-relative regardless of transformed ancestors.
|
|
export default function BackToTop({ dep, threshold = 600 }: { dep?: unknown; threshold?: number }) {
|
|
const { t } = useTranslation();
|
|
const [show, setShow] = useState(false);
|
|
const scrollerRef = useRef<HTMLElement | null>(null);
|
|
|
|
// Listen on the document in the CAPTURE phase and read the scroller off the event, rather than
|
|
// looking <main> up when this binds. Scroll events don't bubble, but they do capture — and the
|
|
// lookup was a race the lazy pages lost: on the FIRST visit to the channel page its chunk is
|
|
// still loading, so the Suspense fallback is on screen, there is no <main> to find, and the
|
|
// effect gave up for good (its dep never changes again). The button then stayed dead for that
|
|
// whole visit and came back only once the chunk was cached. Nothing to find, nothing to race.
|
|
useEffect(() => {
|
|
const onScroll = (e: Event) => {
|
|
const el = e.target as HTMLElement | null;
|
|
if (!el || el.tagName !== "MAIN") return;
|
|
scrollerRef.current = el;
|
|
setShow(el.scrollTop > threshold);
|
|
};
|
|
document.addEventListener("scroll", onScroll, { passive: true, capture: true });
|
|
return () => document.removeEventListener("scroll", onScroll, { capture: true });
|
|
}, [threshold]);
|
|
|
|
// On navigation, re-read where the new page sits: usually the top (so hide), but some pages
|
|
// restore their scroll position. Missing <main> here is now harmless — a page that hasn't
|
|
// rendered hasn't scrolled either, and the listener above picks it up the moment it does.
|
|
useEffect(() => {
|
|
const el = document.querySelector("main");
|
|
scrollerRef.current = el;
|
|
setShow(!!el && el.scrollTop > threshold);
|
|
}, [dep, threshold]);
|
|
|
|
const toTop = () =>
|
|
(scrollerRef.current ?? document.querySelector("main"))?.scrollTo({ top: 0, behavior: "smooth" });
|
|
|
|
// No aria-label/title attributes: ad-block "annoyance" cosmetic filters (e.g. Brave Shields)
|
|
// commonly hide floating corner buttons via attribute selectors like [aria-label="Back to top"].
|
|
// The accessible name comes from a visually-hidden child instead, which those selectors can't match.
|
|
return createPortal(
|
|
<button
|
|
onClick={toTop}
|
|
className={`fixed bottom-5 right-5 z-chrome inline-flex items-center justify-center w-16 h-16 rounded-full glass-card glass-hover text-fg shadow-lg hover:text-accent transition-all duration-200 ${
|
|
show ? "opacity-100 translate-y-0" : "opacity-0 translate-y-3 pointer-events-none"
|
|
}`}
|
|
>
|
|
<ArrowUp className="w-7 h-7" aria-hidden="true" />
|
|
<span className="sr-only">{t("common.backToTop")}</span>
|
|
</button>,
|
|
document.body
|
|
);
|
|
}
|