Of course, the global function call is to be adapted to use jQuery like ( function ( $ ) { ... } ( jQuery ) );

What is the problem you are experiencing and wanting to solve?

See 78d9e3bcf63eb / https://gerrit.wikimedia.org/r/#/c/mediawiki/extensions/TocTree/+/307687/.

In case of a runtime errrors mw.hook() is sometimes not working. This can be overcome by using jQuery.ready function.

Sometimes a runtime error (TypeError) occurs but not in any case. This error prevents proper function of mw.hook().

Console log:

TypeError: data is null[Learn More]  load.php:93:1378
	module.exports</</< https://de.wikivoyage.org/w/load.php:93:1378
	.each https://de.wikivoyage.org/w/load.php:165:859
	jQuery.prototype.each https://de.wikivoyage.org/w/load.php:163:925
	module.exports</< https://de.wikivoyage.org/w/load.php:93:1213
	jQuery.Callbacks/fire https://de.wikivoyage.org/w/load.php:206:897
	jQuery.Callbacks/self.fireWith https://de.wikivoyage.org/w/load.php:208:114
	mw.hook</</<.fire https://de.wikivoyage.org/w/load.php:712:567
	<anonymous> https://de.wikivoyage.org/w/load.php:764:1275
	resolve/</mightThrow https://de.wikivoyage.org/w/load.php:209:848
	resolve/</process< https://de.wikivoyage.org/w/load.php:210:516

TocTree is correct as far as I see. Maybe there is a race-condition somewhere else.

When I load a random page like https://de.wikivoyage.org/wiki/Arnsberg I can see no error. But when I throttle the requests in Firefox then I get

ReferenceError: jQuery33109765425919619954_1554750849522 is not defined

I can see it often (30-40%) when calling the article about Ko Lanta. TOC remains open and the console shows some errors (see above). I use the firefox as well.

There are some missing dependencies in https://de.wikivoyage.org/ that lead to race conditions. But the extension TocTree is not the root cause.

Change 502396 had a related patch set uploaded (by Fomafix; owner: Fomafix):
[mediawiki/extensions/Kartographer@master] Handle the case that getMapData returns null

https://gerrit.wikimedia.org/r/502396

With https://gerrit.wikimedia.org/r/502396 I fix an failure in Maps (Kartographer) which causes the exception in T220308#5091821.

On the JavaScript code in https://de.wikivoyage.org/ there are some dependencies on modules missing. This leads to a race condition is the code fail. This may also lead to some error, which causes TocTree gets not fired.

User scripts on de.wikivoyage.org only seldom use external modules. The dependencies are realized with mw.loader.using()/require() calls. Maybe there are missing dependencies in Kartographer. Some time ago we found such a failure (T197655).

In https://de.wikivoyage.org/wiki/MediaWiki:ListingEditor.js a dependency on module mediawiki.api is missing because it uses mw.Api(). I identified this with a throttled network connection in Firefox.

Fixed in https://de.wikivoyage.org/w/index.php?title=MediaWiki:ListingEditor.js&diff=1195136&oldid=1195058

I found the reason for the race condition:

The HTML of https://de.wikivoyage.org/wiki/Ko_Lanta contains 92 elements with class mw-kartographer-maplink:

$( '.mw-kartographer-maplink[mw-data="interface"]', '.mw-body' ).length // 92

After loading https://de.wikivoyage.org/wiki/MediaWiki:GeneralChanges.js there are 118 elements with class mw-kartographer-maplink. The 26 new elements have no attribute mw-data="interface":

$( '.mw-kartographer-maplink', '.mw-body' ).length // 118

The race condition is also between Maps (Kartographer) and https://de.wikivoyage.org/wiki/MediaWiki:GeneralChanges.js

https://gerrit.wikimedia.org/r/502396 should fix this problem because now it ignores elements without mw-data="interface" instead of raising a runtime error.

Change 502396 merged by jenkins-bot:
[mediawiki/extensions/Kartographer@master] Handle the case that getMapData returns null

https://gerrit.wikimedia.org/r/502396

I can not find any JavaScript errors while loading of https://de.wikivoyage.org/wiki/Arnsberg anymore.