Help:Preview

MediaWiki Handbook: Contents, Readers, Editors, Moderators, System admins +/-

Below the edit box is a Show preview button. Pressing this will show you what the article will look like without actually saving it. It is strongly recommended that you use this prior to saving. This allows you to check what the page will look like first and to check that you haven't made any errors. It also prevents the need for multiple saves. Saving the same article a large number of times in quick succession makes it harder for people to check what changes have been made, and clogs up the page history.

It is helpful, however, to save the page before moving, breaking apart, or combining sections of the article, if you have been making small edits to the article. The difference display is not good at showing paragraph moves, and will not display the small edits clearly if sections are then moved around.

Saving only once is also a way of avoiding edit conflicts, as people will not see the article on recent changes or their watchlist, and therefore they are less likely to try editing it at the same time as you.

If you are logged in, you can set your preferences to show the preview positioned before the edit box instead of after it. If you select this option, the preview will be displayed above the edit box when you click the "Show preview" button while editing a page.

Preference "Show preview on first edit": - when pressing the edit button or otherwise following a link to an edit page, show not only the edit box but also the rendered page, just like after pressing "Show preview".

In the case of automatic conversion of wikitext the preview shows the rendering, while the button "show changes" shows the new wikitext. In the case of recursive conversion of wikitext the preview before/without making manual changes to the wikitext is not the same as the rendering of the current page.

Using show preview also prevents your login timing out, which would mean your edits would not be attributed to your user name. Clicking preview regularly will restart the timer, so you remain logged in. Also, if you are no longer logged in, showing a preview will make you aware of this so you can log in and save your work after that. You can check this by seeing if your user name appears in the upper-right corner when you press preview. If you are not logged in, open Special:Userlogin in a separate window (right-click "Log in" and hit "Open link in new window" or similar). Log in, then go back to your editing and hit "preview" again to make sure all is well. Note that this will clear the minor edit and watch checkboxes, so make sure they're set appropriately again before you finally save the page.

When utilizing this feature during a major edit, consider copying the content into your clipboard. On rare occasions servers may have hiccups, and you could lose your work.

When pressing "preview", also a preview of the edit summary is obtained. Thus links can be checked, including existence detection and the working of piped links. Also, while the summary may be too long to be seen in the input box without scrolling, its preview is fully shown up to the total capacity of the input box.

While editing a template one can see the effect to a page that directly or indirectly calls that template by using the template preview feature: in the area "Preview page with this template", fill in the page name and press the extra button "Show preview"; to return press "Go to editing area".

Limitations, detecting preview mode

If an edit places or changes a section tag, with a reference to it on the same page, for example in p=<section begin=p/>12<section end=p/>, p<sup>2</sup>={{#expr:{{#lst:Help:Preview|p}}^2}} giving p=<section begin=p/>12<section end=p/>, p²=Expression error: Unrecognized punctuation character "{"., the preview is based on the section tags, if any, in the saved version.

{{REVISIONID}} gives the empty string in preview. This can be used to detect preview mode: {{#if:{{REVISIONID}}|This is the normal page|This is the preview}} gives "This is the normal page".

Preview of a footnote

When creating a footnote using section editing, preview only shows the footnote mark, not the footnote content, if the wikitext "<references />" is in another section. A workaround is putting that code temporarily in the section, just for the preview. If previewing the footnotes of a section is needed more often, it may be convenient to put  in the section, and to disable this commenting-out temporarily on preview, e.g. by adding a blank space to the opening comment tag: < !--<references />-->.