Manual:$wgIncludeLegacyJavaScript

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This deprecated feature should no longer be used, but is still available for reasons of backwards compatibility. This feature was deprecated in version 1.26.0.

ResourceLoader: $wgIncludeLegacyJavaScript
Whether to include the mediawiki.legacy JavaScript library (old wikibits.js), and its dependencies.
Introduced in version:	1.17.0 (r83173)
Deprecated in version:	1.26.0 (Gerrit change 229594; git #0ac4f998)
Removed in version:	still in use
Allowed values:	(boolean)
Default value:	`false` (MW 1.27+) `true` (MW 1.17-1.26)
Other settings: Alphabetical \| By function

Details[edit]

Whether to include the mediawiki.legacy JavaScript library (old wikibits.js), and its dependencies.