Template gadgets

Template gadgets are gadgets that load when a certain template is present in a page, usually to implement or extend the functionality of the template. Template gadgets allow features that are otherwise impossible in templates, such as API calls, restricted HTML elements, Codex interfaces, and much more.

Existing template gadgets

Global

Template gadgets in this list are also global gadgets, designed and ready to be used in any wiki (Wikimedia or not) and in any language.

Template:OWID - Embed interactive charts from Our World in Data
Template:Conway's Game of Life - Make an interactive instance of Conway's Game of Life
Template:Langton's ant - Make an interactive instance of Langton's ant
Template:Download PDF - Print or download a specified set of pages
Template:Search - Search the wiki and display the results in a wiki page
Template:Excerpt tree - Navigate excerpt trees
Template:ImageStackPopup - Make a pop-up media gallery viewer suitable for medical images

Local

Template gadgets in this list are not fully globalized yet.

v:Template:Wikidebate - Adds tools for wikidebates
es:Template:Firmar - Easily sign in votes, polls and wikiprojects
es:Template:Formulario - Make forms that inject content into other pages
es:Template:Checkbox - Make checkboxes that preserve the state
es:Template:Wikiproyecto - Add functionality to WikiProjects
es:Template:Hola - Simple demo of a template gadget

Create a new template gadget

If you create a new template gadget, please add it to the appropriate list above so that others may find it, use it and improve it!

General method

To create a template gadget:

Create a template or Lua module that inserts the basic HTML markup you will need, and categorizes pages in a category created just for this purpose
Develop the necessary JavaScript in your common.js
When ready, ask your community to review and promote your JavaScript to the MediaWiki namespace, and define a gadget that loads said JavaScript for pages in your special category

Best practices

Design your template gadget so that it's usable by other wikis (example). Host it at MediaWiki.org (example) and have other wikis load it from there (example).
Separation of concerns can be achieved by moving HTML to the template (example) and CSS to a separate stylesheet (example) that can then be loaded from the template script itself (example).
Encapsulate your code within a class to keep it tidy and avoid unnecessary naming conflicts (example).

Limitations

Template gadgets will not be loaded in AJAX-based previews like Live preview, real-time preview, VisualEditor, mobile app previews, etc.

External links

Announcement on wikimedia-l