In reply to Otto.

I agree it’s a much needed step forward, but in my opinion the warnings (this plugin) should have been added to core first, and give people time before just removing jQuery Migrate and breaking their sites – most end users are non-technical and have no idea what broke or how to fix it, and it tarnishes the reputation of WordPress along the way. I am not sure how it makes sense to remove it first.

Perhaps core could have detected deprecated code, and offered a warning to update plugins etc, and show an option to enable jQuery Migrate again, with a constant warning “jQuery Migrate Helper is installed – you have plugins that need to be updated”, and clicking on the link expands to show a list of the plugins or theme.

The major issue isn’t developers that ignored all the announcements made about it being removed, it’s about the vast number of outdated plugins and themes that are no longer actively maintained, and the developers have ghosted on end users. I am now hunting down old JS code across hundreds of websites, developing patches and search/replace scripts [find .live() and replacing with .on()] etc. Many of these clients pay for quality maintenance and security, and I treat these websites like they are my own, so I’ll ensure they are patched if no updates are available, and no replacements easily implemented.

Sadly, I’m also seeing lots of very popular plugins like Restrict Content Pro using old jQuery libraries and causing warnings (not sure if these are site-breaking issues yet) with their latest just-released versions.

With the pain comes progress, and this will blow over, but warnings for users first before making breaking changes like this should be a priority. These jQuery Migrate removal changes aren’t even mentioned in the 5.5 field guide at all!