Hey all,

TL;DR: * We did not make the breaking change last week for Wikimedia; it is postponed. * MediaWiki 1.24.0 will ship with jQuery Migrate switched off. * Wikimedia & non-Wikimedia wikis can enable jQuery Migrate if needed. * When MediaWiki 1.24 is released, we will switch off jQuery Migrate for Wikimedia wikis.

As we said last month, we are upgrading MediaWiki's jQuery to version 1.11.x [1], which removes some long-deprecated functions. These were done in phase one [2] and two [3] as of last week.

However, we have held off with phase 3 (removing the jQuery Migrate plugin) for a while to give migration a little more time.

The amount of migration work necessary has been much less than I anticipated. Very few scripts have actually needed changing, probably because these features have been deprecated for quite a while now. Some of newer developers may never have even known of these APIs.

Having said that, it does take a while for a message like this to spread out to some members of our large community. While those wiki scripts and gadgets which have active maintainers have been looked into, and (where needed) updated accordingly, a large number of gadgets and scripts in the cluster of Wikimedia wikis have not yet had a chance to get a grip on this, let alone extensions and wikis outside of Wikimedia.

While I don't want to set another deadline, I think it makes sense to ship the jQuery Migrate plugin for one release (with MediaWiki 1.24), and then remove it in MediaWiki 1.25. This will give all wikis' communities and extension authors a few more months until the MediaWiki 1.24 branch point (in Autumn 2014) before they will need to make adjustments to work with MediaWiki master.

MediaWiki 1.24.0 stable will disable support for legacy jQuery by default. If you find you have scripts, gadgets or extensions still using legacy jQuery APIs, you can enable them with a simple line in LocalSettings.php:

$wgIncludejQueryMigrate = true;

And of course when you find you need to do this, please make an effort to ensure the maintainers of those items still using these legacy features are aware of this so they may patch the code accordingly (using the upgrade guide[4] and my earlier announcement [5]). When MediaWiki 1.24 is released, we will switch off jQuery Migrate for Wikimedia wikis.

— Krinkle

[1] https://bugzilla.wikimedia.org/show_bug.cgi?id=44740 [2] https://gerrit.wikimedia.org/r/#/c/131494/ [3] https://gerrit.wikimedia.org/r/#/c/133477/ [4] http://jquery.com/upgrade-guide/1.9/ [5] http://www.mail-archive.com/wikitech-l@lists.wikimedia.org/msg75735.html

On 7 May 2014, at 18:29, Krinkle krinklemail@gmail.com wrote:

Hey all,

TL;DR: jQuery will soon be upgraded from v1.8.3 to v1.11.x (the latest). This major release removes deprecated functionality. Please migrate away from this deprecated functionality as soon as possible.

It's been a long time coming but we're now finally upgrading the jQuery package that ships with MediaWiki.

We used to regularly upgrade jQuery in the past, but got stuck at v1.8 a couple of years ago due to lack of time and concern about disruption. Because of this, many developers have needed to work around bugs that were already fixed in later versions of jQuery. Thankfully, jQuery v1.9 (and its v2 counterpart) has been the first release in jQuery history that needed an upgrade guide[1][2]. It's a major release that cleans up deprecated and dubious functionality.

Migration of existing code in extensions, gadgets, and user & site scripts should be trivial (swapping one method for another, maybe with a slight change to the parameters passed). This is all documented in the upgrade guide[1][2]. The upgrade guide may look scary (as it lists many of your favourite methods), but they are mostly just addressing edge cases.

== Call to action ==

This is a call for you, to:

1. Get familiar with http://jquery.com/upgrade-guide/1.9/.

2. Start migrating your code.

jQuery v1.9 is about removing deprecated functionality. The new functionality is already present in jQuery 1.8 or, in some cases, earlier.

3. Look out for deprecation warnings.

Once instrumentation has begun, using "?debug=true" will log jQuery deprecation warnings to the console. Look for ones marked "JQMIGRATE" [7]. You might also find deprecation notices from mediawiki.js, for more about those see the mail from last October [8].

== Plan ==

1. Instrumentation and logging

The first phase is to instrument jQuery to work out all the areas which will need work. I have started work on loading jQuery Migrate alongside the current version of jQuery. I expect that to land in master this week [6], and roll out on Wikimedia wikis the week after. This will enable you to detect usage of most deprecated functionality through your browser console. Don't forget the upgrade guide[1], as Migrate cannot detect everything.

2. Upgrade and Migrate

After this, the actual upgrade will take place, whilst Migrate stays. This should not break anything since Migrate covers almost all functionality that will be removed. The instrumentation and logging will remain during this phase; the only effective change at this point is whatever jQuery didn't think was worth covering in Migrate or were just one of many bug fixes.

3. Finalise upgrade

Finally, we will remove the migration plugin (both the Migrate compatibility layer and its instrumentation). This will bring us to a clean version of latest jQuery v1.x without compatibility hacks.

A rough timeline:

• 12 May 2014 (1.24wmf4 [9]): Phase 1 – Instrumentation and logging starts. This

will run for 4 weeks (until June 9).

• 19 May 2014 (1.24wmf5): Phase 2 – "Upgrade and Migrate". This will run for 3

weeks (upto June 9). The instrumentation continues during this period.

• 1 June 2014 (1.24wmf7) Finalise upgrade.

== FAQ ==

Q: The upgrade guide is for jQuery v1.9, what about jQuery v1.10 and v1.11?

A: Those are regular updates that only fix bugs and/or introduce non-breaking enhancements. Like jQuery v1.7 and v1.8, we can upgrade to those without any hassle. We'll be fast-forwarding straight from v1.8 to v1.11.

Q: What about the jQuery Migrate plugin?

A: jQuery developed a plugin that adds back some of the removed features (not all, consult the upgrade guide[2] for details). It also logs usage of these to the console.

Q: When will the upgrade happen?

A: In the next few weeks, once we are happy that the impact is reasonably low. An update will be sent to wikitech-l just before this is done as a final reminder. This will be well before the MediaWiki 1.24 branch point for extension authors looking to maintain compatibility.

Q: When are we moving to jQuery v2.x?

A: We are not currently planing to do this. Despite the name, jQuery v2.x doesn't contain any new features compared to jQuery v1 [3]. The main difference is in the reduced support for different browsers and environments; most noticeably, jQuery 2.x drops support for Internet Explorer 8 and below, which MediaWiki is still supporting for now, and is outside the scope of this work. Both v1 and v2 continue to enjoy simultaneous releases for bug fixes and new features. For example, jQuery released v1.11 and v2.1 together[4][5].

-- Krinkle

[1] http://blog.jquery.com/2013/01/15/jquery-1-9-final-jquery-2-0-beta-migrate- final-released/ [2] http://jquery.com/upgrade-guide/1.9/ [3] http://blog.jquery.com/2013/04/18/jquery-2-0-released/ [4] http://blog.jquery.com/2014/01/24/jquery-1-11-and-2-1-released/ [5] http://blog.jquery.com/2013/05/24/jquery-1-10-0-and-2-0-1-released/ [6] https://gerrit.wikimedia.org/r/131494 [7] https://github.com/jquery/jquery-migrate/blob/master/warnings.md [8] http://www.mail-archive.com/wikitech-l@lists.wikimedia.org/msg72198.html [9] https://www.mediawiki.org/wiki/MediaWiki_1.24/Roadmap