wikishia:User scripts/Techniques

This page will collect various techniques for achieving common tasks needed in writing user scripts. Discussion about limitations, relative portability, and speed of the various alternatives is strongly encouraged. There is a lot of duplication and non-optimal efforts out there, and this will hopefully encourage us to write tighter, more correct code, both easier and faster.

An advanced API for interacting with Wikipedia content is being developed, large parts of which are already operational. The various possibilities are described at mw:API. The idea is to send an AJAX request (see below) to the API containing a query. The result of this query can be returned in several formats, of which JSON is perhaps the most useful, see below.

Identifying the type of page

This refers to techniques for identifying the current namespace of the current page, whether or not it is an edit page, a preview page, a Special page, etc.

Preview pages

document.getElementById("wikiPreview")

• From: Add Edit Top Link

Edit pages

document.getElementById("editform")

This will be null when not editing a page.

History pages

wgAction === 'history'

• Based on: Changes since I last edited

Special pages

wgCanonicalNamespace === 'Special'

Pages with history

document.getElementById('ca-history')

• From: Add purge to tabs

Editable pages

document.getElementById('ca-edit')

Be advised that this also returns the edit tab if you're currently editing the page.

• From: Add edit section 0

Getting various parts of a page

Getting the page title and namespace

• wgCanonicalNamespace contains the name of the namespace, e.g. "".
• wgCanonicalSpecialPageName is normally false but for special pages it contains the non-localized name.
• wgNamespaceNumber is 0 for the main namespace, -1 for special pages, and other values for other namespaces.
• wgPageName is the article name as it is shown on the url, e.g. "Kumano_Kodō". It includes the namespace identifier.
• wgTitle is the title of the article, without namespace identifier or escaping, e.g. "Kumano Kodō".

Getting the various toolbars (personal, tabs, sidebar)

var tabs = document.getElementById(BAR NAME).getElementsByTagName('ul')[0];

• Where BAR NAME is one of the following strings:

  'p-cactions'

  the tabs at the top of the page (with the article, discussion, edit, history, move, and watch links)

  'p-personal'

  the personal toolbar (i.e. the one at the top, with a link to user page, user talk, prefs, watchlist, contribs, log out)

  'p-navigation'

  the navigation toolbar (i.e. Main page, Featured Content, etc.)

  'p-interaction'

  the interaction toolbar, below the navigation toolbar

  'p-tb'

  the toolbox (What links here, Related changes etc.)

• This gets the toolbar in a form that can be the first arg to wikishia:User scripts/Scripts/Add LI link

TODO: Someone please test the search and toolbox ones, and see if they work the same. Thanks!

The search box is 'p-search' but there's no <ul> element in it. [ælfəks] 10:38, 24 June 2006 (UTC)

The search box can be retrieved by simply replacing the 'ul' in getElementsByTagName('ul') with 'div', as all the toolboxes' ids are in div tags. Extremecircuitz (Talk | Userboxes page) 20:17, 21 October 2007 (UTC)

Inserting content

document.getElementById("content").insertBefore(document.createTextNode("abcdef"), document.getElementsByTagName("h1")[0])

• On a page with a h1 heading, this works in Firefox 1.0.4 on OSX, but fails on some other browsers. Anyone know how or why? JesseW 20:58, 29 August 2005 (UTC)

• No, but does it help if you delay execution until the page has loaded? Lupin|talk|popups 12:14, 4 October 2005 (UTC)

Pressing buttons

document.editform.wpDiff.click()

• Presses the diff button.

Altering existing interface links

To change the url, name, or any other aspect of existing tab buttons, personal bar links, or other links, use the following: (where id is the id of the link to be changed, e.g. "pt-preferences", "ca-edit", "n-portal" or "t-whatlinkshere"; url is the new URL, and name is the new displayed name for the link, e.g. "my preferences", "edit this page", "Community Portal", or "What links here")

document.getElementById(id).childNodes[0].href=url
q=document.getElementById(id).firstChild; q.removeChild(q.firstChild); q.appendChild(document.createTextNode(name)) 

Onload Structure

jQuery can attach functions to the onLoad event:

$( myFunction );

Functions can also be written inline as

$( function() {
    // Code here
} );

Do not assign window.onload to a function directly, as this overwrites any other onLoad functions that may have been previously set.

Include an external js-file on wikipedia

mw.loader.load is a loader method to load external javascript or css:

mw.loader.load( 'http://meta.wikimedia.org/w/index.php?title=MediaWiki:Wikiminiatlas.js&action=raw&ctype=text/javascript', 'text/javascript' );
mw.loader.load( 'http://example.org/mystyles.css', 'text/css' );
mw.loader.load( 'http://example.org/mystyles.js', 'text/javascript' );

AJAX

See Wikipedia:WikiProject User scripts/Guide/Ajax

$.getScript('http://example.org/foo.js', function () {
 // Foo.js is loaded!
} )

Automatic edits

On edit pages you can find the textbox with the wikitext like this:

var t = document.editform.wpTextbox1;

Then you can read and write the wikitext:

if(/^\s*$/.test(t.value)) ... ;
t.value = t.value + "\n==New section==\n";

To make an edit based on the current selection, you can use:

insertTags(tagOpen, tagClose, sampleText)

The last parameter will be used if the selection turns out to be empty.

JSON

Parsing JSON text, as delivered by e.g. the MediaWiki API is done automatically when using jQuery utilities:

jQuery.getJSON(
  mw.util.wikiScript( 'api' ), {
    'format': 'json',
    'action': 'query',
    'meta': 'userinfo'
  }, function ( data ) {
    // data.query.userinfo
  }
);

Update a script

Scripts on a user's computer are updated to the most recent version version by bypassing (clearing) the browser cache - the user has to push Shift-Reload (Mozilla) or Shift-F5 (MS-IE). A JavaScript can do the same by calling:

window.location.reload(true);

This forced reload ("forceGet") immediately reloads the current page including all images, scripts, and stylesheets. This should not be done from edit or preview pages as the edits might get lost.

For users that have a lot of scripts installed, reloading them all may take up a lot of time. See Gerbrant.mng.decache and its talk page for example code on how you can let JavaScript remove arbitrary files from your browser cache using an external application.

Edit a page on another Wikimedia wiki

Although not commonly used, CORS is enabled between all Wikimedia wikis. For an example of cross-wiki editing, see here.