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Reddit Multi Column: fix residual iOS stacked-column flash on post tap (v0.3.24) #20

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Merged
heyflorin merged 1 commit into from
Jun 27, 2026
Merged

Reddit Multi Column: fix residual iOS stacked-column flash on post tap (v0.3.24) #20

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73 changes: 58 additions & 15 deletions Reddit Multi Column.user.js
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
// ==UserScript==
// @name Reddit Multi Column
// @namespace https://gist.github.com/c6p/463892bb243f611f2a3cfa4268c6435e
// @version 0.3.23
// @version 0.3.24
// @description Multi column layout for reddit redesign (with SPA nav support)
// @author Can Altıparmak
// @homepageURL https://gist.github.com/c6p/463892bb243f611f2a3cfa4268c6435e
Expand All @@ -13,6 +13,30 @@
// ==/UserScript==
/* jshint esversion: 6 */

// --- 0.3.24 ------------------------------------------------------------------
// Closes the iOS / iPadOS stacked-column flash that 0.3.23 still let through
// "sometimes" when tapping a post.
//
// Cause: 0.3.23 recognised the lingering previous feed by reference equality
// (found === priorFeed). But Reddit's router navigates to a post with a
// pushState IMMEDIATELY followed by a replaceState to the canonical permalink
// (the URL with the title slug) — two path changes in the same task. onNavigate
// nulls `parent` on the first, so the second captures priorFeed = null. The
// re-search then re-finds the still-visible gridded feed, (found === priorFeed)
// is false, and the grid is stood down WHILE VISIBLE — the stacked flash. The
// fast desktop swap hides this; the slow iOS/iPadOS swap leaves the un-gridded
// feed on screen. (Reproduced deterministically in a headless browser harness:
// single-nav was clean, the push→replace double-nav flashed every original card
// at full opacity until Reddit removed the feed.)
//
// Fix: mark every feed we grid with a durable flag (__rmcGridded) and decide
// suppression from that flag instead of the fragile priorFeed reference. A
// gridded node re-found on a post-detail page is, by definition, the previous
// feed lingering through the swap, so it stays hidden no matter how priorFeed
// was lost. priorFeed is kept only as a secondary signal. No stacked frame ever
// paints, on single- or double-navigation.
// -----------------------------------------------------------------------------

// --- 0.3.23 ------------------------------------------------------------------
// Fixes a brief flash on iOS / iPadOS where the multi-column feed collapses to
// a single stacked column for a moment when you tap a post, before the post
Expand Down Expand Up @@ -141,11 +165,12 @@
let parent = null;
let currentPath = location.pathname;

// The feed we were gridding right before the most recent navigation. If
// Reddit hasn't torn it down by the time we re-search (slow SPA swaps on
// iOS/iPadOS), we'll re-find this exact node on the new — post-detail —
// page; recognising it lets us keep it hidden instead of un-gridding it
// into a visible stacked flash. See the 0.3.23 note above.
// The feed we were gridding right before the most recent navigation, kept as
// a SECONDARY signal for recognising a lingering previous feed on the new
// page. It can be lost on a pushState→replaceState navigation (the first
// change nulls `parent`, so the second captures null here), which is why the
// primary signal is now the durable `__rmcGridded` marker set on each feed we
// grid — see the 0.3.24 note above and engageFeed.
let priorFeed = null;
// True while we're deliberately keeping a stood-down feed hidden (the
// lingering-feed-on-post-detail case). Guards revealFeed so a stray
Expand Down Expand Up @@ -456,6 +481,15 @@
// We're actually gridding now, so any prior suppression is over.
suppressed = false;
if (parent.style.position !== "relative") parent.style.position = "relative";
// Durable mark on the node we grid. If this exact node is re-found later
// on a post-detail page (the previous feed lingering through Reddit's
// slow SPA swap), engageFeed uses this to keep it HIDDEN instead of
// un-gridding it into a visible stacked flash — and it survives losing
// the `priorFeed` reference (e.g. a pushState→replaceState pair where the
// first nav already nulled it). Never cleared: a feed node is only ever a
// pure-post feed (re-gridded) or removed by Reddit, so a lingering marked
// node on a stand-down page is always a previous grid, never live content.
parent.__rmcGridded = true;

const containerWidth = parent.clientWidth;
const newColumns = columnCountFor(containerWidth);
Expand Down Expand Up @@ -653,16 +687,25 @@
// and laying it out.
const standdown = isMixedFeed() || isTooNarrow();
if (standdown) {
// Was THIS node one we'd gridded? Read it before standDown() runs —
// standDown() doesn't touch the marker, but read first regardless so
// the decision can never depend on standDown()'s side effects. The
// `priorFeed` reference is kept only as a secondary signal; the
// durable `__rmcGridded` marker is what makes this survive Reddit's
// pushState→replaceState navigation (two path changes in one task,
// the first of which nulls priorFeed — the race that still let a
// stacked frame flash through on iOS/iPadOS in 0.3.23).
const wasGridded = !!found.__rmcGridded || found === priorFeed;
standDown();
// The previous gridded feed, re-found while we're now on a
// post-detail page, is lingering through Reddit's SPA swap (slow on
// iOS/iPadOS). Revealing it would un-grid it into a stacked flash
// before the post renders. Keep it hidden instead — there's no feed
// to show on a post-detail page; it'll be removed, or re-gridded and
// revealed on back-navigation. Any other stood-down feed (a genuine
// profile/search mixed feed, or a too-narrow phone layout) is real
// content and must be shown.
if (found === priorFeed && isPostDetail()) {
// A node we'd gridded, re-found while we're now on a post-detail
// page, is the previous feed lingering through Reddit's SPA swap
// (slow on iOS/iPadOS). Revealing it would un-grid it into a stacked
// flash before the post renders. Keep it hidden instead — there's no
// feed to show on a post-detail page; it'll be removed, or re-gridded
// and revealed on back-navigation. Any other stood-down feed (a
// genuine profile/search mixed feed we never gridded, or a too-narrow
// phone layout) is real content and must be shown.
if (wasGridded && isPostDetail()) {
suppressed = true;
hideFeed();
} else {
Expand Down