WP 5.6 jQuery Breaking Changes

[brianjohnhanna]

In WP 5.6, the versions of jQuery and related libraries shipped with core have been upgraded to the following versions:

• jQuery 3.5.1
• jQuery Migrate 3.3.2
• jQuery UI 1.12.1

This appears to cause some issues with this plugin's Javascript and the bundled Fullcalendar library (v2.2.7).

Known Issues

• [Admin] Calendar view throws zIndex is not a function error. Related to this change in jQuery UI (see admin-calendar.js:1333)
• [Admin + FE] Calendar view "week" and "day" view does not load events and only shows "All Day" header. Likely related to old Fullcalendar version incompatibility with newer jQuery versions

Temp Fix

The WordPress core team has provided a backwards compatibility plugin which can be installed and configured to use the legacy version of jQuery. This fixes the issue with Fullcalendar. It does, however, add a large banner to every page in the admin which is less than desirable on client sites.

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WP Version: 5.6 EO Version: 3.10.2

[rbywater]

Came across these issues and I managed to temporarily work around it by hacking the fullcalendar.js file to the 3.10.2 version and that restored the calendar functionality partly (albeit with some label issues etc. which is probably because there's more files that need updating than just that one).

(It should probably be noted that even with the jQuery Migrate Helper plugin installed on my 5.6 Wordpress instance, it didn't appear to mitigate any of the issues so not sure why)

[stephenharris]

It should be fixed in the 3.10.3 update

[rbywater]

Thanks @stephenharris - the 3.10.3 update fixed the zIndex issue but didn't appear to fix the second week/day issue until I hacked a new version of fullcalendar.js in. Not sure if it was just an issue at my end or not then though...

[stephenharris]

Thanks @rbywater - nope, I overlooked that. It should be fixed in 3.10.4

[brianjohnhanna]

@stephenharris thanks for jumping those fixes so quickly. I actually maintain a fork of the plugin... I see you published 3.10.4 on WP plugin repository but any chance you can publish those changes and tags here on Github so I can sync the fork?