Manual:$wgIncludeLegacyJavaScript

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:1.39.0 (Gerrit change 831217; git #a3cb9d53)
Allowed values:(boolean)
Default value:false (MW 1.27+)
true (MW 1.17-1.26)

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