Help:Template previews

Shared templates and Lua modules can affect many articles. TemplateSandbox lets you preview a real article with proposed code before changing the live shared component. Existing edit and page-creation permissions still apply; a preview does not publish or grant approval.

Preview an unsaved template edit

Open the shared template in the source editor and change its code.
Find “Preview page with this template” below the editor and enter an article that uses it.
Use that preview button and check the article’s output, including default/missing parameters, categories and mobile layout.
Save the shared template only when the preview is satisfactory.

The preview field is enabled on Template and Module pages. For Lua, test through a page that invokes the module. Check existing usage before changing a shared component. Individual and cascading page protection still apply.

Preview sandbox copies together

Use Special:TemplateSandbox when testing several templates or modules together. For a prefix User:Example/sandbox, copies retain their original namespace inside the prefix:

Template:Character Panel → User:Example/sandbox/Template:Character Panel
Module:Document status → User:Example/sandbox/Module:Document status

Enter the article to preview and that prefix on the special page. Only copies actually present under the prefix override live components. Ordinary Template:Name/sandbox pages can also be used through prefix-page redirects as described in the upstream documentation. Creating or saving a sandbox copy is a normal edit and requires the appropriate permissions; the special-page preview does not save the target article.

TemplateStyles code is separate from template/Lua previewing. Preview changed styles and verify them on desktop/mobile before publishing; do not assume a template preview replaces that check.

See Echoes of the Flesh:Templates, Echoes of the Flesh:Access levels and MediaWiki’s TemplateSandbox guide.