Manual:Live preview/en

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 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
 * undo/redo history in the editing window is kept

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 API and the -option of the Revisions API, to submit the new version of the text in order to receive parsed preview or diff changeset in the Edit page.


 * Implementation

Since it is dynamic on the client side, it requires JavaScript to work. Should JavaScript be deactivated, the edit will preview traditionally (with page reload), even if this feature is activated. This is an instance of progressive enhancement.