TL;DR: In April 2017, the jQuery library in MediaWiki was upgraded from 1.x
to 3.x (the current stable version), with the jQuery Migrate plugin enabled
ease migration. We temporarily still load jQuery 1.x on Wikimedia wikis.
Read about the API changes at https://jquery.com/upgrade-guide/3.0/
== Upgrade guide ==
An overview of the important changes is available at:
This page also contains advice on how to migrate your code. In most cases
it involves fairly
simple changes, such as using a different method name, or adding quotes in
The vast majority of the added requirements and removed methods are
the jQuery Migrate plugin with a deprecation warning in the console. As
such, it's unlikely
your code will require any immediate changes.
If you do find a deprecation warning in the console, you can use the
to find out more:
Once jQuery 3 is in Wikimedia production (with jQuery Migrate) it will be
find uses of deprecated methods with the deprecation warnings. However, you
need to wait for August to start migrating. The methods removed in jQuery 3
been deprecated for a while already, and their replacements are already
in jQuery 1.x in production, today.
== Timeline ==
* April 2017: jQuery 3 lands in MediaWiki core master with jQuery Migrate
* April to July 2017: Testing and fixing of issues arising from the switch.
* July 2017: jQuery 3 enabled in Wikimedia's Beta Cluster. 
* August 2017: jQuery 3 enabled on Wikimedia wikis in production.
jQuery 3 will also be released as part of MediaWiki 1.30.0 (expected in
November 2017). 
As part of MediaWiki 1.30, inclusion of jQuery Migrate will made
configurable so that sites
that have already migrated may disable the plugin for better run-time
Track progress at <https://phabricator.wikimedia.org/T124742>.