Reading/Web/Desktop Improvements/Features/Loading Vector 2010 scripts

When working on Vector 2022, we wanted to ease the transition from Vector legacy (2010) for communities. To fulfill this, we didn't change how scripts worked. So Vector 2022 would initially:


 * load both and  for sites
 * load both and  for users

This meant less work for the communities at the time of changing the default skin for their wikis.

But this was temporary. In late 2023 or early 2024, Vector 2022 will not load any scripts for Vector 2010 on any wiki. Communities, interface administrators, and individual users will need to make some decisions.

It is also possible for communities to request the change to take place sooner. To do that, write on our talk page or create a new task on Phabricator, tagged, that requests the disabling of.

A community may decide to do nothing. But the new behaviour of Vector 2022 will become the default. Delaying action here is likely to cause problems for users.

Examples
In late 2023 or early 2024, users will suddenly see the message "Behaviour after site request". This will mean local site styles would have stopped loading (if those would still be relied on). In consequence, many user scripts will stop loading unexpectedly.

Communities' decisions
We recommend that communities:
 * discuss this change – please decide if it's preferable for your community to change this configuration earlier than the end of the year,
 * if/when your community decides to do so:
 * notify any users it might affect, to avoid disruption or confusion,
 * use this as an opportunity to encourage housekeeping. E.g. deletion of local skin JS/CSS that is no longer used,
 * after making changes to your code, write on our talk page or create a new task on Phabricator, tagged, that requests the disabling of  . Example: T332809.

Actions for interface administrators
General cleanup, as needed.
 * CSS: Copy any necessary content from into.
 * JavaScript: Migrate any content from into  . (NOT duplicating it, because that can cause errors, unless you know what you are doing.)

Actions for users

 * CSS: Copy or migrate any necessary content from into  – OR –.
 * JavaScript: Migrate any content from into  – OR –  . (NOT duplicating it, because that can cause errors, unless you know what you are doing.)