See also Manual:Interface/JavaScript for use of JavaScript overrides on a local wiki install.

As of MediaWiki 1.17 most JavaScript code in MediaWiki is object-oriented and packaged as ResourceLoader modules that other code can depend on. Also jQuery was introduced in MediaWiki core in MediaWiki 1.16, and loaded by default on every page as of 1.17.

Before MediaWiki 1.16, most JavaScript was in wikibits.js and other files in /skins/common/.

See alsoEdit