[SPIKE] Kartographer uses MobileFrontend hook for section expansion, not applying to Parsoid
Closed, ResolvedPublic2 Estimated Story PointsBUG REPORT
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Description

Many projects have been using parsoid now.
While doing some code cleanup in MobileFrontend I noticed Kartographer makes use of the mobileFrontend.section-toggled hook which is not present in the Parsoid version and in the legacy parser marked as Internal for use inside ExternalGuidance.
https://gerrit.wikimedia.org/g/mediawiki/extensions/Kartographer/+/2914baaa1260d7cf3cf9961fcb3e7503c028478e/modules/mapframe/mapframe.js#102

Is this still needed? If so could you provide context on what bug it is addressing so the #readers-growth team can consider whether to ?

TODO

Determine if Kartographer still needs it (And if there is a bug in production that has resurfaced relating to this)
- alternative method found using InteractionObserver, and merged
If needed, update the documentation that Kartographer uses the hook and add it to the Parsoid sectionCollapsing code.
- n/a as not needed
If not remove hook from code.
- done

Details

Related Changes in Gerrit:

	Subject	Repo	Branch	Lines +/-
	Use intersection observer to invalidate size	mediawiki/extensions/Kartographer	master	+10 -8
	Remove mobileFrontend.section-toggled hook	mediawiki/extensions/MobileFrontend	master	+2 -13

Customize query in gerrit

Related Objects

Mentioned Here: T414221: Frontend performance issue for tablet devices loading parsoid content

Event Timeline

Jdlrobson-WMF created this task.Oct 30 2025, 9:20 PM

Restricted Application added a subscriber: Aklapper. · View Herald TranscriptOct 30 2025, 9:20 PM

Jdlrobson-WMF added a project: Reader Growth Team.Oct 30 2025, 9:29 PM

Jdlrobson-WMF updated the task description. (Show Details)

Hook may have already been removed due to a patch Eric made the other day.

HSwan-WMF triaged this task as Low priority.Nov 19 2025, 6:13 PM

HSwan-WMF moved this task from Incoming/Inbox to Needs Refinement on the Reader Growth Team board.Nov 19 2025, 6:15 PM

it is mentioned right above there right ?

// Special case for collapsed maps.
// When the container is initially hidden Leaflet is not able to
// calculate the expected size when visible. We need to force
// updating the map to the new container size on `expand`.

// do the same for mobile sections

So kartographer (or rather Leaflet) needs to calculate its own size and when it is not rendered, it cannot do so (because its parent has no dimensions). So it has to force (a redo of) this calculation step when it has been made visible.

This is probably only for dynamic maps on things like wikivoyage, where we draw an inline dynamic map

@TheDJ I saw the comment but this hook has never been executed in Parsoid which has been live on wikivoyage for quite some time and nobody reported an issue, so we're questioning whether it's still needed. Can we replicate the original bug?

Is this the same issue (I can't reliably replicate it)?
https://en.wikivoyage.org/wiki/San_Carlos_de_Bariloche

Screenshot 2025-11-25 at 10.50.10 AM.png (822×493 px, 149 KB)

Could IntersectionObserver be used here instead to address this issue?

In T408875#11407005, @Jdlrobson-WMF wrote:

Is this the same issue (I can't reliably replicate it)?
https://en.wikivoyage.org/wiki/San_Carlos_de_Bariloche

Yes it is.

Could IntersectionObserver be used here instead to address this issue?

Not sure

HSwan-WMF renamed this task from Kartographer uses MobileFrontend hook for section expansion, not applying to Parsoid to [SPIKE] Kartographer uses MobileFrontend hook for section expansion, not applying to Parsoid.Nov 26 2025, 5:47 PM

HSwan-WMF set the point value for this task to 2.

HSwan-WMF moved this task from Needs Refinement to Ready on the Reader Growth Team board.Dec 3 2025, 4:59 PM

Jdlrobson-WMF added a project: Readers Essential Work 2025 (WE6.3.4 Fix bugs within the reading experience across platforms for Parsoid Read Views).Dec 11 2025, 1:14 AM

matthiasmullie claimed this task.Dec 17 2025, 3:04 PM

SherryYang-WMF moved this task from Ready to Sprint 1 (Jan 6 - Feb 3) Q3 25/26 on the Reader Growth Team board.Jan 6 2026, 6:05 PM

SherryYang-WMF edited projects, added Reader Growth Team (Sprint 1 (Jan 6 - Feb 3) Q3 25/26); removed Reader Growth Team.

Jdlrobson-WMF moved this task from Backlog to Non-blockers on the Readers Essential Work 2025 (WE6.3.4 Fix bugs within the reading experience across platforms for Parsoid Read Views) board.Jan 6 2026, 6:30 PM

matthiasmullie moved this task from Committed to Doing on the Reader Growth Team (Sprint 1 (Jan 6 - Feb 3) Q3 25/26) board.Jan 7 2026, 5:07 PM

Change #1224637 had a related patch set uploaded (by Matthias Mullie; author: Matthias Mullie):

[mediawiki/extensions/Kartographer@master] Use intersection observer to invalidate size

https://gerrit.wikimedia.org/r/1224637

gerritbot added a project: Patch-For-Review.Jan 8 2026, 12:05 PM

Change #1224650 had a related patch set uploaded (by Matthias Mullie; author: Matthias Mullie):

[mediawiki/extensions/MobileFrontend@master] Remove mobileFrontend.section-toggled hook

https://gerrit.wikimedia.org/r/1224650

In T408875#11407166, @TheDJ wrote:

Could IntersectionObserver be used here instead to address this issue?

Not sure

I tested with a (local version of) https://en.wikivoyage.org/wiki/San_Carlos_de_Bariloche, and it seems to work well enough with a simple intersection observer instead of relying on that hook.
Patches in CR.

Does the bug still exist in production? If so, what are the steps to replicate the bug? I ask because I'm not able to replicate the bug on mobile view (locally or production wiki) using the example page, https://en.wikivoyage.org/wiki/San_Carlos_de_Bariloche
For local setup, I configured LocalSettings to retrieve content from the Wikivoyage API ($wgMFMwApiContentProviderBaseUri = "https://en.wikivoyage.org/w/api.php").

Visit https://en.wikivoyage.org/wiki/San_Carlos_de_Bariloche?useparsoid=1 on a desktop/tablet device. At 900px you'll notice the sections visibly expand (which itself is a bug that I just raised here: T414221: Frontend performance issue for tablet devices loading parsoid content ). Make sure all sections are expanded on load and you are in the Minerva skin.
Scroll to "Get in" section. Map should look like

Note you can replicate this locally with latest version of MobileFrontendContentProvider and http://localhost:8888/w/index.php/San_Carlos_de_Bariloche?mfproviderproject=wikivoyage&useparsoid=1

Without bug: I shoulds see no flash.

Thanks @Jdlrobson-WMF ! My viewport was too small to see the bug in production. Now, I notice the bug when sections are initially expanded (640px and larger) and collapsed (639px and smaller). The map is broken between 481-1119px on Minerva mobile view with Parsoid enabled (Parsoid appears to be the default for Wikivoyage in production)

FYI I wasn't really able to reproduce through above scenario, but loading it on my phone (iPhone; width around 390px) with sections collapsed consistently showed the issue upon expanding the section.

Jdlrobson-WMF moved this task from Code Review to QA on the Reader Growth Team (Sprint 1 (Jan 6 - Feb 3) Q3 25/26) board.Jan 12 2026, 7:06 PM

Change #1224637 merged by jenkins-bot:

[mediawiki/extensions/Kartographer@master] Use intersection observer to invalidate size

https://gerrit.wikimedia.org/r/1224637

Change #1224650 merged by jenkins-bot:

[mediawiki/extensions/MobileFrontend@master] Remove mobileFrontend.section-toggled hook

https://gerrit.wikimedia.org/r/1224650

Maintenance_bot removed a project: Patch-For-Review.Jan 12 2026, 7:31 PM

Jdlrobson-WMF moved this task from Non-blockers to Tracking on the Readers Essential Work 2025 (WE6.3.4 Fix bugs within the reading experience across platforms for Parsoid Read Views) board.Jan 12 2026, 10:36 PM

The issue is consistently reproducible in wmf.10 on a real mobile device (e.g. iPhone) - some other examples:
https://en.wikivoyage.org/wiki/Manchester/Castlefield-Petersfield
https://en.wikivoyage.org/wiki/Altrincham

Checked on enwikivoyage wmf.11 - issue is fixed.

Etonkovidova moved this task from QA to Signoff on the Reader Growth Team (Sprint 1 (Jan 6 - Feb 3) Q3 25/26) board.Wed, Jan 14, 10:52 PM

Confirmed that todo list is all complete and fix is live for enwikivoyage. Signing off and closing. :)

	F70653192: Screenshot 2025-11-25 at 10.50.10 AM.png
	Nov 25 2025, 6:51 PM

[SPIKE] Kartographer uses MobileFrontend hook for section expansion, not applying to ParsoidClosed, ResolvedPublic2 Estimated Story PointsBUG REPORTActions