TinyMCE is a MediaWiki extension that lets users edit wiki pages using the popular open-source JavaScript-based WYSIWYG editor TinyMCE developed by Ephox Corp. The editor can be added to the standard edit page, to forms defined by the Page Forms extension, and to regular pages in view mode. Users are given total control over the configuration of TinyMCE from LocalSettings.php.  This includes the ability to have multiple editor instances on a single page (in both page view mode and in forms) with different configurations for each editor instance if desired.

The TinyMCE extension provides users with an alternative to the standard VisualEditor. For example, they may want to integrate their wikis in an environment where other tools may already use TinyMCE, such as Angular, Bootstrap Django, Rails, React, Swing, Vue, Joomla, and WordPress to name a few.

The extension also allows users to access TinyMCE plugins produced by Ephox or third parties. For example, included with this extension is the plugin for Fontawesome.  Other plugins that can be used include the N1ED bootstrap editor and the CodeMirror code editor.

The current release (version 1.0) has undergone a major rewrite to use TinyMCE 5 and to give much greater functionality in the editor. This includes significant enhancements to: the copy/paste and drag/drop functionality; the file upload functionality; editing html embedded in the wiki text; and editing embedded plain text (pre and nowiki blocks); and inserting and editing references and comments.

More details can be found on the extension’s page https://www.mediawiki.org/wiki/Extension:TinyMCE