The ContentHandler facility adds support for arbitrary content types on wiki pages, instead of relying on wikitext for everything. It was introduced in MediaWiki 1.21.
Each kind of content ("content model") supported by MediaWiki is identified by unique name. The content model determines how a page's content is rendered, compared, stored, edited, and so on.
Built-in content types are:
- wikitext - wikitext, as usual
- javascript - user provided javascript code