peter
e257e2aca0
Prettier 3 (pinned), printWidth 100, double quotes — chosen to match the existing hand-formatting and minimise reflow. This commit is ONLY the mechanical format pass (`prettier --write`) plus the config/ignore/scripts, isolated so it never pollutes a feature diff. Verified behaviour-neutral: typecheck, eslint (0 errors), and vitest all green before and after. See .git-blame-ignore-revs — `git blame` skips this sha.
64 lines
3.2 KiB
TypeScript
64 lines
3.2 KiB
TypeScript
import { useEffect, useRef, useState } from "react";
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import { createPortal } from "react-dom";
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import { ArrowUp } from "lucide-react";
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import { useTranslation } from "react-i18next";
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// A floating "back to top" button that fades in once the current page's scroll container is
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// scrolled past a threshold, and smooth-scrolls it back to the top. Every page scrolls inside a
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// <main class="overflow-y-auto"> — the normal pages share App's, the channel page renders its own
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// — so this follows whichever one is mounted. Portaled to <body> so its fixed position is
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// viewport-relative regardless of transformed ancestors.
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export default function BackToTop({ dep, threshold = 600 }: { dep?: unknown; threshold?: number }) {
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const { t } = useTranslation();
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const [show, setShow] = useState(false);
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const scrollerRef = useRef<HTMLElement | null>(null);
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// Listen on the document in the CAPTURE phase and read the scroller off the event, rather than
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// looking <main> up when this binds. Scroll events don't bubble, but they do capture — and the
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// lookup was a race the lazy pages lost: on the FIRST visit to the channel page its chunk is
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// still loading, so the Suspense fallback is on screen, there is no <main> to find, and the
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// effect gave up for good (its dep never changes again). The button then stayed dead for that
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// whole visit and came back only once the chunk was cached. Nothing to find, nothing to race.
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useEffect(() => {
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const onScroll = (e: Event) => {
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const el = e.target as HTMLElement | null;
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if (!el || el.tagName !== "MAIN") return;
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scrollerRef.current = el;
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setShow(el.scrollTop > threshold);
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};
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document.addEventListener("scroll", onScroll, { passive: true, capture: true });
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return () => document.removeEventListener("scroll", onScroll, { capture: true });
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}, [threshold]);
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// On navigation, re-read where the new page sits: usually the top (so hide), but some pages
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// restore their scroll position. Missing <main> here is now harmless — a page that hasn't
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// rendered hasn't scrolled either, and the listener above picks it up the moment it does.
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useEffect(() => {
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const el = document.querySelector("main");
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scrollerRef.current = el;
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setShow(!!el && el.scrollTop > threshold);
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}, [dep, threshold]);
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const toTop = () =>
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(scrollerRef.current ?? document.querySelector("main"))?.scrollTo({
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top: 0,
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behavior: "smooth",
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});
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// No aria-label/title attributes: ad-block "annoyance" cosmetic filters (e.g. Brave Shields)
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// commonly hide floating corner buttons via attribute selectors like [aria-label="Back to top"].
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// The accessible name comes from a visually-hidden child instead, which those selectors can't match.
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return createPortal(
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<button
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onClick={toTop}
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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 ${
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show ? "opacity-100 translate-y-0" : "opacity-0 translate-y-3 pointer-events-none"
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}`}
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>
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<ArrowUp className="w-7 h-7" aria-hidden="true" />
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<span className="sr-only">{t("common.backToTop")}</span>
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</button>,
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document.body,
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);
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}
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