Manual:Live preview

Live preview is a feature of MediaWiki which allows showing a preview of an article or section on an edit form without reloading the remaining HTML code of the form.

It has some bugs, see 1>phab:T41272|live preview tracking bug for an up to date list.

Enabling live preview
Live preview is on or off depending on a setting in the "editing" tab of your user preferences page, by default off.

Advantages

 * less incoming traffic: wikicode and all the menus are not received from the server again


 * faster response time


 * same cursor position in the editing window.

Disadvantages
Only preview area is updated, which means:


 * scripts are not executed if they do not use the   hook.


 * some parts of the interface like interlanguage links, transclusion list etc might not be updated correctly.
 * navigating in the browser history – with the preview – no longer works

Technical details
A live preview makes use of the parse>Special:MyLanguage/API:Parsing wikitext#parse|Parse API and the -option of the rev>Special:MyLanguage/API:Revisions|Revisions API, to submit the new version of the text in order to receive parsed preview or diff changeset in the Edit page.

Implementation ]
 * [https://phabricator.wikimedia.org/diffusion/MW/browse/master/resources/src/mediawiki.action/mediawiki.action.edit.preview.js