Help:Collapsing


 * This functionality may require changes to MediaWiki:Common.js on your wiki.

Collapsible tables provide a way to collapse and uncollapse a table when a show/hide button is clicked. The code for this feature is usually found in the MediaWiki:Common.js (see Help:Collapsing/js_code for Javascript code).

The initial state of any collapsible content can be controlled using a "collapsible table", because it also allows a table with only one element with content, and a header.

Simple example
Tables are simpler to work with, as you merely need to add the collapsible class to the table itself. For the [hide]/[show] link to appear, the table's first row must be a header row, that is, one of the cells in the first row must be declared with an exclamation mark (in wikisyntax). The use of the class wikitable in the example below is merely for appearance; it is not needed for collapsible to function.

Using the syntax above, collapsible tables are often used to always display an introduction to, or summary of, a lengthy discussion or section of content, while hiding the majority of that content from immediate view. The summary message is put in the header cell, and the content is placed into the body cell. The content is then easily accessible by clicking the 'show' button. The collapsible functionality is also available in larger and more complicated tables, as long as there is a header cell in the first row of the table.

Collapsing tables by default
Just using the collapsible class produces a table which is expanded by default, but can be collapsed by the reader. It is also possible to create tables which are collapsed by default, and can be optionally expanded. There are several methods for doing this, depending on the situations in which you want the table to collapse.

'collapsed'
Adding the collapsed class will cause the table to always be initially collapsed, no matter what happens around it. It is the simplest method for doing so. Using the examples above:

'autocollapse'
Adding the autocollapse class causes the table to collapse when there are 2 or more collapsible tables on the page (this threshold might be different on other projects). The example below, therefore, collapses because there are numerous collapsible tables on the page.

'innercollapse' and 'outercollapse'
Using this pair of classes, it is possible to make a table collapsed by default only when it is contained within a particular object, such as another table. This is mainly useful for tables inside templates, which are often nested.

Sortable tables
Collapsible tables can be combined with the sortable tables functionality without difficulty. However, because the hide/show button is placed in the first header cell located, its positioning can look a bit peculiar if the table is not wide enough:

Possible alternative is sortable table inside one-cell collapsible table, see example on the right.

Customization
Registered users can edit their personal js file file to change some of the variables used.

Other HTML elements
The code that performs the manipulation only checks for table elements, so these classes will not work for other elements, such as   </tt> or    </tt>. There is a similar feature for use with   </tt> elements, called "NavFrame". See NavFrame

Limitations
This functionality requires the end-user's browser to have Javascript enabled. If Javascript is disabled, the default behaviour is to show the content.