Phasing out old jQuery versions - Wikitech-l

7 Aug 2021

Hi,
(If you don't use jQuery in your code or gadgets, you can ignore this email)

in 2017 jQuery 3 got deployed to production and a backward compatibility
layer was introduced to prevent old codes from breaking. Since then it has
been emitting warnings in your console. All start with "JQMIGRATE". Some of
these old jquery breaking changes have been deprecated in versions released
in 2006 or 2007.

We are slowly pulling the plug and removing that compatibility layer (which
would reduce the default payload and make Wikipedia faster for everyone).
Yesterday, that layer was removed from mediawiki CI, tests in gated
extensions have passed but there is a chance that your extension might be
broken in CI now if it's not part of gated extensions. In that case, please
fix the errors.

We will move forward to deploy this in Wikimedia wikis soon meaning really
old gadgets will also break if they don't fix their code. Please check your
console and if you see jquery migration deprecation warnings, attend to
them because they will break soon. Firefox doesn't give trace to warnings
anymore but in Chrome (and using ?debug=1) you can easily find the source
of deprecation warnings.

We already fixed many usages in code and gadgets and we will make sure to
fix heavily used gadgets and user scripts but we can't possibly fix
everything and it's the maintainers' responsibility to fix deprecation
warnings that is being emitted for years.

Another aspect is that if you use jquery.ui, this library has been
deprecated as well and I recommend moving away from it but if you still use
it and migration can be hard, we patched our jquery.ui fork to make sure it
doesn't break. Still, if you find a part of jquery.ui that has not been
fixed, let me know.

You can track the work in https://phabricator.wikimedia.org/T280944 and the
metrics of deprecations can be found in
https://grafana.wikimedia.org/d/000000037/mw-js-deprecate?orgId=1&refre…

Thank you and sorry for the inconvenience.
-- 
Amir (he/him)