Extension:CodeMirror

**MediaWiki extensions manual**
CodeMirror; Release status: stable
Implementation	User interface
Description	Provides syntax highlighting in editors
Author(s)	Pavel Astakhov; MusikAnimal; Bhsd;
Maintainer(s)	Community Tech
Latest version	6.0.0
Compatibility policy	Snapshots releases along with MediaWiki. Master is not backward compatible.
PHP	7.4+
License	GNU General Public License 2.0 or later
Download	Download extension ; Git [?]: GitHub); Gerrit code review; Git commit log; Download source tarball; ; README
Help	Help:Extension:CodeMirror
	Parameters $wgCodeMirrorV6; $wgCodeMirrorConflictingGadgets; $wgCodeMirrorTitleCompletion; $wgCodeMirrorDefaultPreferences; $wgCodeMirrorLineNumberingNamespaces;
	Hooks used EditPage::showEditForm:initial; EditPage::showReadOnlyForm:initial; GetBetaFeaturePreferences; GetPreferences; UploadForm:initial;
Quarterly downloads	288 (Ranked 13th)
Public wikis using	6,549 (Ranked 62nd)
	Translate the CodeMirror extension if it is available at translatewiki.net
Issues	Report a bug

Translate this page

This documentation refers to CodeMirror 6 – the new version of CodeMirror. It is slated to replace CodeMirror 5 by MediaWiki version 1.45 (release timeline). See the migration guide on migrating clients to CodeMirror 6, and Extension:CodeMirror/5 for CodeMirror 5 documentation.

CodeMirror currently does not support syntax highlighting of Scribunto, JavaScript, CSS and JSON pages, but might in the future (T373711). In the meantime, use Extension:CodeEditor instead.

The CodeMirror extension provides CodeMirror library. For usage and a list of features, see Help:Extension:CodeMirror .

In 2024, the extension was upgraded to the new major version, CodeMirror 6, and with it many new features were added.

Usage

For usage of this extension, see Help:Extension:CodeMirror .

For the JavaScript documentation, see docs.wikimedia.org/CodeMirror.

Installation

Download and move the extracted CodeMirror folder to your extensions/ directory.
Developers and code contributors should install the extension from Git instead, using:cd extensions/ git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/CodeMirror
Add the following code at the bottom of your LocalSettings.php file:
```
wfLoadExtension( 'CodeMirror' );
```
Configure as required.
Done – Navigate to Special:Version on your wiki to verify that the extension is successfully installed.

Configuration

To enable CodeMirror for all users by default, add the following to your LocalSettings.php :

# Enables use of CodeMirror by default but still allow users to disable it
$wgDefaultUserOptions[ 'usecodemirror' ] = true;

$wgCodeMirrorV6

Temporary feature flag to control the migration to CodeMirror 6 (T259059).

$wgCodeMirrorConflictingGadgets

An array of gadget names that, if enabled, will prevent CodeMirror from loading. Defaults to wikEd.

$wgCodeMirrorDefaultPreferences

Control which features are enabled by default for all users. Use true or false to enable or disable a feature entirely, or provide an array containing namespace IDs (integers) or content models (strings). For example, to limit autocompletion to JavaScript pages or templates, you could use:

$wgCodeMirrorDefaultPreferences[ 'autocomplete' ] = [ CONTENT_MODEL_JAVASCRIPT, NS_TEMPLATE ];

$wgCodeMirrorDefaultPreferences
Feature	2017 editor compatibility	Default value
`activeLine`	N	`false`
`bidiIsolation`	N	`false`
`bracketMatching`		`true`
`lineNumbering`		`true`
`lineWrapping`	^[1]	`true`
`specialChars`	N	`true`
`codeFolding`	N	`true`
`autocomplete`	N	`true`
`openLinks`	N	`true`

Differences from CodeMirror 5

New features

No longer requires the use of WikiEditor .
Significant performance improvements.
Right-to-left support (T358804).
Code folding (T30684).
Autocompletion (T95100).
Quickly open links with modifier key + click (T303392).
Improved search panel (T371436).
CodeMirror preferences (T359498).
Syntax highlighting on read-only pages (T301615).
Robust JavaScript API for integration with extensions, gadgets, and user scripts.

Deprecations and other changes

The ResourceLoader modules are changing. See the migration guide .
The ext.CodeMirror.switch hook has been deprecated. Use ext.CodeMirror.toggle instead.
The .cm-mw-mnemonic CSS class has been renamed to .cm-mw-html-entity.
The .cm-mw-template-name-mnemonic class has been removed. Use .cm-mw-template-ground.cm-html-entity instead.
The .cm-mw-apostrophes-bold and .cm-mw-apostrophes-italic CSS classes have been removed. Use .cm-mw-apostrophes instead.
Line-level styling for <nowiki>, <pre>, or any tag without an associated TagMode has been removed (T351686).
Mixed languages within wikitext are not yet supported (T357480). The only known usage of this with CodeMirror 5 is Extension:PhpTags .
The browser's native search functionality (using Ctrl+F) has been replaced with search functionality built into CodeMirror. This is necessary to maintain performance (T303664).

Migration guide

MediaWiki version:

≥ 1.43

This guide applies to MediaWiki 1.43 and later. All integrations should aim to be migrated by the release of MediaWiki 1.45 (release timeline ).

MediaWiki configuration

$wgCodeMirrorLineNumberingNamespaces is deprecated. Configure $wgCodeMirrorDefaultPreferences instead.

ResourceLoader modules

Ensure you're using the new .v6 modules . Because CodeMirror 6 no longer relies on WikiEditor, there are some naming and behaviourial changes from the CodeMirror 5 counterparts:

Old module	New module (MW 1.43)	New module (MW 1.44+)	Description
`ext.CodeMirror`	`ext.CodeMirror.v6.WikiEditor.init`	`ext.CodeMirror.init`	CodeMirror integration for WikiEditor on `#wpTextbox1` (the normal editing textarea) and only for wikitext.
N/A	`ext.CodeMirror.v6.WikiEditor`	`ext.CodeMirror.WikiEditor`	Exports the CodeMirrorWikiEditor class
N/A	`ext.CodeMirror.v6.init`	`ext.CodeMirror.init`	CodeMirror for `#wpTextbox1` and only for wikitext.
`ext.CodeMirror.lib`	`ext.CodeMirror.v6.lib`	`ext.CodeMirror.lib`	Exports CodeMirror internals.
`ext.CodeMirror.addons`	N/A	N/A	This packaged the bracket matching feature in CodeMirror 5. Bracket matching is default behaviour in CodeMirror 6.
`ext.CodeMirror.mode.mediawiki`	`ext.CodeMirror.v6.mode.mediawiki`	`ext.CodeMirror.mode.mediawiki`	The MediaWiki language mode.
N/A	`ext.CodeMirror.v6`	`ext.CodeMirror`	Exports the CodeMirror class.
`ext.CodeMirror.visualEditor`	`ext.CodeMirror.visualEditor.init`	`ext.CodeMirror.init`	Integration with the 2017 wikitext editor .
`ext.CodeMirror.lib.mode.php`	N/A	N/A	CodeMirror 6 will not provide these modules. They are rarely used and have no corresponding content model in MediaWiki. If you want support for these languages, you'll need to install the bundle the code yourself.
`ext.CodeMirror.lib.mode.clike`
`ext.CodeMirror.lib.mode.htmlmixed`
`ext.CodeMirror.lib.mode.xml`
`ext.CodeMirror.lib.mode.javascript`	TBD	`ext.CodeMirror.lib.mode.javascript`	These languages are planned to be supported in CodeMirror 6.
`ext.CodeMirror.lib.mode.css`		`ext.CodeMirror.lib.mode.css`
N/A		`ext.CodeMirror.lib.mode.lua`
N/A		`ext.CodeMirror.lib.mode.json`
N/A		`ext.CodeMirror.lib.mode.vue`

With the release of MediaWiki 1.45, the old modules will be replaced with the news ones, and for some time the .v6 modules will be aliased before being removed entirely.

Gadgets and user scripts

The CodeMirror global has been removed entirely. For example, CodeMirror.fromTextArea( myTextarea ) will no longer work. Instead, first load the desired ResourceLoader modules , instantiate a CodeMirror object, and call the initialize() method.

If your script relies on the ext.CodeMirror.switch hook to change the way it interacts with the editor, you'll need to use ext.CodeMirror.toggle instead, or alternatively listen to an event. See the JavaScript integration section for more information.

CSS

The .CodeMirror element no longer exists. Use .cm-editor instead for the entire CodeMirror DOM, or .cm-content for the inner content (doesn't include the search panel, for example).

See deprecations and other changes to other CSS classes.

Integration

MediaWiki Extensions

Registering a new tag for MediaWiki

If you simply want CodeMirror to recognize a tag that is added by an extension, you can do so using the CodeMirrorTagModes extension attribute . For example, to register the tag ‎<foo> as something containing wikitext, you would add the following to extension.json:

{
	"attributes": {
		"CodeMirror": {
			"TagModes": [
				"foo": "mediawiki"
			]
		}
	}
}

CodeMirror will then highlight the content inside ‎<foo>...‎</foo> as wikitext.

Registering a tag so that CodeMirror treats the contents as something other than wikitext is currently not supported (T357480). If a tag is not registered, CodeMirror will highlight the contents as non-wikitext in the same way it highlights the contents of a ‎<nowiki>...‎</nowiki> tag.

Registering content models

CodeMirror's integration with WikiEditor currently works only with wikitext, but will eventually support other content types.

For the time being, if you need wikitext syntax highlighting on the main textarea (#wpTextbox1) for a content model other than wikitext, you can use the CodeMirrorContentModels extension attribute . For example, Extension:Proofread Page registers the proofread-page content type:

{
	"attributes": {
		"CodeMirror": {
			"ContentModels": [
				"proofread-page"
			]
		}
	}
}

PluginModules

CodeMirrorPluginModules is an extension attribute that allows side-loading a module with CodeMirror. This unconditionally loads the module whenever the ext.CodeMirror.v6 module is loaded. If your plugin is only used in specific circumstances, consider having it check whether it is needed, and dynamically load the core code from a different module. This will avoid unnecessarily consuming end user bandwidth.

extension.json:

{
	"attributes": {
		"CodeMirror": {
			"PluginModules": [
				"ext.MyExtension.CodeMirror"
			]
		}
	}
}

ext.MyExtension.CodeMirror.js:

/ Only load in the template namespace
if ( mw.config.get( 'wgNamespaceNumber' ) === 10 ) {
	return mw.loader.using( 'ext.MyExtension.CodeMirror.core' );
}
return Promise.resolve();

JavaScript

The CodeMirror editor is not an actual toggled off.

For detecting changes to the document, using an event or a hook is likely the simplest. For reading and making changes, jQuery.textSelection may be convenient.

For more complex integrations or those who need better preformance, you can add your own extension to a new or an existing CodeMirror instance.

Using jQuery.textSelection

If you simply want to fetch or make changes to the document text, jQuery.textSelection is the easiest and most reliable means to do so. Usage of jQuery.textSelection on the textarea is bubbled up to CodeMirror, so you don't need to have any knowledge of whether CodeMirror is enabled:

const $textarea = $( '#wpTextbox1' )
const content = $textarea.textSelection( 'getContents' );
/ Append "Foobar" to the content.
$textarea.textSelection( 'setContents', content + '\nFoobar' );

Using jQuery's .val() on #wpTextbox1 can be used,^[2] however this isn't recommended and may not work in all editors, such as the 2017 wikitext editor .

Using ResourceLoader

The CodeMirror extension provides a number of ResourceLoader modules for use by user scripts, gadgets, and extensions. To make use of CodeMirror, you'll need at minimum the ext.CodeMirror.v6 module, along with the desired language. For MediaWiki wikitext, you'd use ext.CodeMirror.v6.mode.mediawiki.

Here is an example of how to apply wikitext syntax highlighting to any arbitrary textarea, using the default set of features:

mw.loader.using( [ 'ext.CodeMirror.v6', 'ext.CodeMirror.v6.mode.mediawiki' ] ).then( ( require ) => {
	const CodeMirror = require( 'ext.CodeMirror.v6' );
	const mediawikiLang = require( 'ext.CodeMirror.v6.mode.mediawiki' );
	const cm = new CodeMirror( myTextarea, mediawikiLang() );
	cm.initialize();
} );

If you also want WikiEditor:

mw.loader.using( [
	'ext.wikiEditor',
	'ext.CodeMirror.v6.WikiEditor',
	'ext.CodeMirror.v6.mode.mediawiki'
] ).then( ( require ) => {
	const textarea = document.getElementById( 'wpTextbox1' );
	mw.addWikiEditor( $( textarea ) );
    const CodeMirrorWikiEditor = require( 'ext.CodeMirror.v6.WikiEditor' );
	const mediawikiLang = require( 'ext.CodeMirror.v6.mode.mediawiki' );
	const cmWe = new CodeMirrorWikiEditor( textarea, mediawikiLang() );
	cmWe.initialize();
} );

ResourceLoader modules
Module	Description
`ext.CodeMirror.v6.lib`	The core CodeMirror library. You shouldn't need to require this directly unless you need access to the upstream CodeMirror API.
`ext.CodeMirror.v6`	The basic CodeMirror integration for MediaWiki editors. This module exports the CodeMirror class.
`ext.CodeMirror.v6.mode.mediawiki`	The MediaWiki language mode. Use this in conjunction with the `ext.CodeMirror.v6` module.
`ext.CodeMirror.v6.init` (internal)	The main entrypoint for action=edit requests. Not intended for external use.
`ext.CodeMirror.v6.WikiEditor`	CodeMirror integration for WikiEditor. This module exports the CodeMirrorWikiEditor class.
`ext.CodeMirror.visualEditor.init`	CodeMirror integration with the 2017 wikitext editor , and only for wikitext.

Using hooks

You can also integrate with CodeMirror by using frontend hooks. These allow you to run code just before or after CodeMirror has loaded, or react to changes to the document.

Frontend hooks
Hook	Description
`ext.CodeMirror.initialize`	Called just before CodeMirror is initialized. This can be used to manipulate the DOM to suit CodeMirror (i.e. if you manipulate WikiEditor's DOM, you may need this). Parameters (`HTMLTextAreaElement`) The current "editor", most likely `#wpTextbox1`. (`ve.ui.Surface`) The VisualEditor surface CodeMirror is bound to, if applicable.
`ext.CodeMirror.ready`	Called just after CodeMirror is initialized. Parameters (`CodeMirror`) The CodeMirror instance.
`ext.CodeMirror.toggle`	Called when CodeMirror is toggled on or off. Parameters (`boolean`) Whether CodeMirror is now enabled. (`CodeMirror`) The CodeMirror instance. (`HTMLTextAreaElement`) The original textarea.
`ext.CodeMirror.destroy`	Called just after CodeMirror is destroyed and the original textarea is restored. Parameters (`HTMLTextAreaElement`) The original textarea.
`ext.CodeMirror.input`	Called when document changes are made in CodeMirror. Note that the textarea may not be updated yet. Parameters (`ViewUpdate`) The ViewUpdate object.
`ext.CodeMirror.preferences.ready`	Fired just before CodeMirrorPreferences has been instantiated. Paramaters (`CodeMirrorPreferences`) The CodeMirrorPreferences instance.
`ext.CodeMirror.preferences.apply`	Fired when a CodeMirror preference is enabled or initially applied. Parameters (`string`) The name of the preference, which is also the corresponding key in the compartmentRegistry.
`ext.CodeMirror.preferences.change`	Fired when a CodeMirror preference is enabled or disabled by the user. Paramaters (`string`) The name of the preference. (`boolean`) The new value of the preference.
`ext.CodeMirror.preferences.display` (internal)	Fired when the preferences panel is constructed, just before it is displayed. Parameters (`HTMLDivElement`) The preferences panel container.
`ext.CodeMirror.keymap` (internal)	Fired when the keyboard shortcut help dialog is opened.
`ext.CodeMirror.search` (internal)	Fired when the search panel is opened.

Using events

The following textarea for developer convenience:

blur
focus
keyup
keydown
scroll

Using these events, you can integrate with CodeMirror using the same code as the original textarea:

myTextarea.addEventListener( 'keyup', ( event ) => {
	console.log( event.key );
} );

Extending CodeMirror

You can import the ext.CodeMirror.v6.lib module to get access to the upstream Extension when instantiating a CodeMirror or CodeMirrorWikiEditor instance.

For example, to provide your own Extension that reacts to changes made in CodeMirror:

mw.loader.using( [ 'ext.CodeMirror.v6', 'ext.CodeMirror.v6.mode.mediawiki' ] ).then( ( require ) => {
	const CodeMirror = require( 'ext.CodeMirror.v6' );
	const mediawikiLang = require( 'ext.CodeMirror.v6.mode.mediawiki' );
	/ ext.CodeMirror.v6.lib is a dependency of ext.CodeMirror.v6, so it's already loaded at this point.
	const { EditorView } = require( 'ext.CodeMirror.v6.lib' );
	const myExtension = EditorView.updateListener.of( ( /** @type {ViewUpdate} */ update ) => {
		if ( update.docChanged ) {
		    / do something
		    console.log( update.changes );
		}
	} );
	const cm = new CodeMirror( myTextarea, mediawikiLang() );
    cm.initialize( [ cm.defaultExtensions, myExtension ] );
} );

Or if you need to interact with an existng CodeMirror instance:

/ Ensure CodeMirror is initialized first
mw.hook( 'ext.CodeMirror.ready' ).add( ( cm ) => {
	const { EditorView } = require( 'ext.CodeMirror.v6.lib' );
	const myExtension = EditorView.updateListener.of( ( /** @type {ViewUpdate} */ update ) => {
		if ( update.docChanged ) {
		    / do something
		    console.log( update.changes );
		}
	} );
	cm.applyExtension( myExtension );
} );

Another means of listening to changes is using the ext.CodeMirror.input hook :

mw.hook( 'ext.CodeMirror.input' ).add( ( update ) => {
	/ Print the ChangeSet to the console
	console.log( update.changes.toJSON() );
} );

Notes

↑ Line wrapping cannot be disabled in the 2017 editor.
↑ phab:T384556

InitialiseSettings.php configuration files to see where it's installed. A full list of the extensions installed on a particular wiki can be seen on the wiki's Special:Version page.

This extension is included in the following wiki farms/hosts and/or packages:

This is not an authoritative list. Some wiki farms/hosts and/or packages may contain this extension even if they are not listed here. Always check with your wiki farms/hosts or bundle to confirm.

[1] Line wrapping cannot be disabled in the 2017 editor.

[2] :T384556

[1]

[2]

CodeMirror Release status: stable

Implementation	User interface
Description	Provides syntax highlighting in editors
Author(s)	Pavel Astakhov MusikAnimal Bhsd
Maintainer(s)	Community Tech
Latest version	6.0.0
Compatibility policy	Snapshots releases along with MediaWiki. Master is not backward compatible.
PHP	7.4+
License	GNU General Public License 2.0 or later
Download	Download extension Git ^[?]: GitHub) Gerrit code review Git commit log Download source tarball README
Help	Help:Extension:CodeMirror
Parameters $wgCodeMirrorV6 $wgCodeMirrorConflictingGadgets $wgCodeMirrorTitleCompletion $wgCodeMirrorDefaultPreferences $wgCodeMirrorLineNumberingNamespaces
Hooks used EditPage::showEditForm:initial EditPage::showReadOnlyForm:initial GetBetaFeaturePreferences GetPreferences UploadForm:initial
Quarterly downloads	288 (Ranked 13^th)
Public wikis using	6,549 (Ranked 62^nd)
Translate the CodeMirror extension if it is available at translatewiki.net
Issues	Report a bug