Once we have deprecation notices (T58550),Timeline:
* {icon check color=green} Add option to disable legacy globals: wgLegacyJavaScriptGlobals. – T30916, 49ce5de7d94. (MediaWiki 1.17 in 2011)
* {icon check color=green} Add deprecation notices for accessing `mw.config.get()` when wgLegacyJavaScriptGlobals is enabled. – T58550, 24f84b08cf91ef. (MediaWiki 1.25 in 2014)
* Migrate usage and gradually disable on Wikimedia wikis:
* {icon check color=green} Turn it off on test2.wikipedia.org. – T67011, bbfba08d31 (2014)
* {icon check color=green} {T177259}
* [ ] Turn it off in Continuous Integration (Jenkins mw-config).
* [ ] Turn it off on Beta Cluster.
* [ ] Turn it off on [group0 wikis](https://wikitech.wikimedia.org/wiki/Deployments/One_week) (test.wikipedia.org, mediawiki.org, and read-only wikis).
* [ ] Turn it off on [group1 wikis](https://wikitech.wikimedia.org/wiki/Deployments/One_week) (mostly non-Wikipedia).
turn them off by default (T35837) and leave that state as migration period (1 release cycle),* [ ] Turn it off [everywhere](https://wikitech.wikimedia.org/wiki/Deployments/One_week) (+group2: Wikipedia).
* [ ] Turn it off by default in MediaWiki core. we should r– T35837 (in release N)
* [ ] Remove them.e feature. – (in release N+1 or later)