We have various modules (infamously jquery.ui but also jquery.tipsy) that we want to discourage use of for reasons such as performance, mobile compatibility and replicating functionality of a preferred library. However because these modules are in core they are commonly used in new extensions unless someone who knows what their future fate is.
I would like to find a way to speed up deprecation of these modules so that we can deprecate the targets attribute.
As a straw man proposal I would suggest a 'deprecated' => true ResourceLoader entry that when present (possibly in debug mode) outputs a message in the console such as
This page uses the deprecated modules jquery.ui, jquery.tipsy. Offending modules should be written without these dependencies: 'ext.foo.module', 'ext.xyz.module'