]> scripts.mit.edu Git - autoinstallsdev/mediawiki.git/blobdiff - resources/src/mediawiki/mediawiki.js
MediaWiki 1.30.2
[autoinstallsdev/mediawiki.git] / resources / src / mediawiki / mediawiki.js
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+/**
+ * Base library for MediaWiki.
+ *
+ * Exposed globally as `mediaWiki` with `mw` as shortcut.
+ *
+ * @class mw
+ * @alternateClassName mediaWiki
+ * @singleton
+ */
+
+/* global mwNow */
+/* eslint-disable no-use-before-define */
+
+( function ( $ ) {
+       'use strict';
+
+       var mw, StringSet, log,
+               hasOwn = Object.prototype.hasOwnProperty,
+               slice = Array.prototype.slice,
+               trackCallbacks = $.Callbacks( 'memory' ),
+               trackHandlers = [],
+               trackQueue = [];
+
+       /**
+        * FNV132 hash function
+        *
+        * This function implements the 32-bit version of FNV-1.
+        * It is equivalent to hash( 'fnv132', ... ) in PHP, except
+        * its output is base 36 rather than hex.
+        * See <https://en.wikipedia.org/wiki/FNV_hash_function>
+        *
+        * @private
+        * @param {string} str String to hash
+        * @return {string} hash as an seven-character base 36 string
+        */
+       function fnv132( str ) {
+               /* eslint-disable no-bitwise */
+               var hash = 0x811C9DC5,
+                       i;
+
+               for ( i = 0; i < str.length; i++ ) {
+                       hash += ( hash << 1 ) + ( hash << 4 ) + ( hash << 7 ) + ( hash << 8 ) + ( hash << 24 );
+                       hash ^= str.charCodeAt( i );
+               }
+
+               hash = ( hash >>> 0 ).toString( 36 );
+               while ( hash.length < 7 ) {
+                       hash = '0' + hash;
+               }
+
+               return hash;
+               /* eslint-enable no-bitwise */
+       }
+
+       function defineFallbacks() {
+               // <https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Set>
+               StringSet = window.Set || ( function () {
+                       /**
+                        * @private
+                        * @class
+                        */
+                       function StringSet() {
+                               this.set = {};
+                       }
+                       StringSet.prototype.add = function ( value ) {
+                               this.set[ value ] = true;
+                       };
+                       StringSet.prototype.has = function ( value ) {
+                               return hasOwn.call( this.set, value );
+                       };
+                       return StringSet;
+               }() );
+       }
+
+       /**
+        * Create an object that can be read from or written to via methods that allow
+        * interaction both with single and multiple properties at once.
+        *
+        * @private
+        * @class mw.Map
+        *
+        * @constructor
+        * @param {boolean} [global=false] Whether to synchronise =values to the global
+        *  window object (for backwards-compatibility with mw.config; T72470). Values are
+        *  copied in one direction only. Changes to globals do not reflect in the map.
+        */
+       function Map( global ) {
+               this.values = {};
+               if ( global === true ) {
+                       // Override #set to also set the global variable
+                       this.set = function ( selection, value ) {
+                               var s;
+
+                               if ( $.isPlainObject( selection ) ) {
+                                       for ( s in selection ) {
+                                               setGlobalMapValue( this, s, selection[ s ] );
+                                       }
+                                       return true;
+                               }
+                               if ( typeof selection === 'string' && arguments.length ) {
+                                       setGlobalMapValue( this, selection, value );
+                                       return true;
+                               }
+                               return false;
+                       };
+               }
+       }
+
+       /**
+        * Alias property to the global object.
+        *
+        * @private
+        * @static
+        * @param {mw.Map} map
+        * @param {string} key
+        * @param {Mixed} value
+        */
+       function setGlobalMapValue( map, key, value ) {
+               map.values[ key ] = value;
+               log.deprecate(
+                       window,
+                       key,
+                       value,
+                       // Deprecation notice for mw.config globals (T58550, T72470)
+                       map === mw.config && 'Use mw.config instead.'
+               );
+       }
+
+       Map.prototype = {
+               constructor: Map,
+
+               /**
+                * Get the value of one or more keys.
+                *
+                * If called with no arguments, all values are returned.
+                *
+                * @param {string|Array} [selection] Key or array of keys to retrieve values for.
+                * @param {Mixed} [fallback=null] Value for keys that don't exist.
+                * @return {Mixed|Object|null} If selection was a string, returns the value,
+                *  If selection was an array, returns an object of key/values.
+                *  If no selection is passed, a new object with all key/values is returned.
+                */
+               get: function ( selection, fallback ) {
+                       var results, i;
+                       fallback = arguments.length > 1 ? fallback : null;
+
+                       if ( Array.isArray( selection ) ) {
+                               results = {};
+                               for ( i = 0; i < selection.length; i++ ) {
+                                       if ( typeof selection[ i ] === 'string' ) {
+                                               results[ selection[ i ] ] = hasOwn.call( this.values, selection[ i ] ) ?
+                                                       this.values[ selection[ i ] ] :
+                                                       fallback;
+                                       }
+                               }
+                               return results;
+                       }
+
+                       if ( typeof selection === 'string' ) {
+                               return hasOwn.call( this.values, selection ) ?
+                                       this.values[ selection ] :
+                                       fallback;
+                       }
+
+                       if ( selection === undefined ) {
+                               results = {};
+                               for ( i in this.values ) {
+                                       results[ i ] = this.values[ i ];
+                               }
+                               return results;
+                       }
+
+                       // Invalid selection key
+                       return fallback;
+               },
+
+               /**
+                * Set one or more key/value pairs.
+                *
+                * @param {string|Object} selection Key to set value for, or object mapping keys to values
+                * @param {Mixed} [value] Value to set (optional, only in use when key is a string)
+                * @return {boolean} True on success, false on failure
+                */
+               set: function ( selection, value ) {
+                       var s;
+
+                       if ( $.isPlainObject( selection ) ) {
+                               for ( s in selection ) {
+                                       this.values[ s ] = selection[ s ];
+                               }
+                               return true;
+                       }
+                       if ( typeof selection === 'string' && arguments.length > 1 ) {
+                               this.values[ selection ] = value;
+                               return true;
+                       }
+                       return false;
+               },
+
+               /**
+                * Check if one or more keys exist.
+                *
+                * @param {Mixed} selection Key or array of keys to check
+                * @return {boolean} True if the key(s) exist
+                */
+               exists: function ( selection ) {
+                       var i;
+                       if ( Array.isArray( selection ) ) {
+                               for ( i = 0; i < selection.length; i++ ) {
+                                       if ( typeof selection[ i ] !== 'string' || !hasOwn.call( this.values, selection[ i ] ) ) {
+                                               return false;
+                                       }
+                               }
+                               return true;
+                       }
+                       return typeof selection === 'string' && hasOwn.call( this.values, selection );
+               }
+       };
+
+       /**
+        * Object constructor for messages.
+        *
+        * Similar to the Message class in MediaWiki PHP.
+        *
+        * Format defaults to 'text'.
+        *
+        *     @example
+        *
+        *     var obj, str;
+        *     mw.messages.set( {
+        *         'hello': 'Hello world',
+        *         'hello-user': 'Hello, $1!',
+        *         'welcome-user': 'Welcome back to $2, $1! Last visit by $1: $3'
+        *     } );
+        *
+        *     obj = new mw.Message( mw.messages, 'hello' );
+        *     mw.log( obj.text() );
+        *     // Hello world
+        *
+        *     obj = new mw.Message( mw.messages, 'hello-user', [ 'John Doe' ] );
+        *     mw.log( obj.text() );
+        *     // Hello, John Doe!
+        *
+        *     obj = new mw.Message( mw.messages, 'welcome-user', [ 'John Doe', 'Wikipedia', '2 hours ago' ] );
+        *     mw.log( obj.text() );
+        *     // Welcome back to Wikipedia, John Doe! Last visit by John Doe: 2 hours ago
+        *
+        *     // Using mw.message shortcut
+        *     obj = mw.message( 'hello-user', 'John Doe' );
+        *     mw.log( obj.text() );
+        *     // Hello, John Doe!
+        *
+        *     // Using mw.msg shortcut
+        *     str = mw.msg( 'hello-user', 'John Doe' );
+        *     mw.log( str );
+        *     // Hello, John Doe!
+        *
+        *     // Different formats
+        *     obj = new mw.Message( mw.messages, 'hello-user', [ 'John "Wiki" <3 Doe' ] );
+        *
+        *     obj.format = 'text';
+        *     str = obj.toString();
+        *     // Same as:
+        *     str = obj.text();
+        *
+        *     mw.log( str );
+        *     // Hello, John "Wiki" <3 Doe!
+        *
+        *     mw.log( obj.escaped() );
+        *     // Hello, John &quot;Wiki&quot; &lt;3 Doe!
+        *
+        * @class mw.Message
+        *
+        * @constructor
+        * @param {mw.Map} map Message store
+        * @param {string} key
+        * @param {Array} [parameters]
+        */
+       function Message( map, key, parameters ) {
+               this.format = 'text';
+               this.map = map;
+               this.key = key;
+               this.parameters = parameters === undefined ? [] : slice.call( parameters );
+               return this;
+       }
+
+       Message.prototype = {
+               /**
+                * Get parsed contents of the message.
+                *
+                * The default parser does simple $N replacements and nothing else.
+                * This may be overridden to provide a more complex message parser.
+                * The primary override is in the mediawiki.jqueryMsg module.
+                *
+                * This function will not be called for nonexistent messages.
+                *
+                * @return {string} Parsed message
+                */
+               parser: function () {
+                       return mw.format.apply( null, [ this.map.get( this.key ) ].concat( this.parameters ) );
+               },
+
+               // eslint-disable-next-line valid-jsdoc
+               /**
+                * Add (does not replace) parameters for `$N` placeholder values.
+                *
+                * @param {Array} parameters
+                * @chainable
+                */
+               params: function ( parameters ) {
+                       var i;
+                       for ( i = 0; i < parameters.length; i++ ) {
+                               this.parameters.push( parameters[ i ] );
+                       }
+                       return this;
+               },
+
+               /**
+                * Convert message object to its string form based on current format.
+                *
+                * @return {string} Message as a string in the current form, or `<key>` if key
+                *  does not exist.
+                */
+               toString: function () {
+                       var text;
+
+                       if ( !this.exists() ) {
+                               // Use ⧼key⧽ as text if key does not exist
+                               // Err on the side of safety, ensure that the output
+                               // is always html safe in the event the message key is
+                               // missing, since in that case its highly likely the
+                               // message key is user-controlled.
+                               // '⧼' is used instead of '<' to side-step any
+                               // double-escaping issues.
+                               // (Keep synchronised with Message::toString() in PHP.)
+                               return '⧼' + mw.html.escape( this.key ) + '⧽';
+                       }
+
+                       if ( this.format === 'plain' || this.format === 'text' || this.format === 'parse' ) {
+                               text = this.parser();
+                       }
+
+                       if ( this.format === 'escaped' ) {
+                               text = this.parser();
+                               text = mw.html.escape( text );
+                       }
+
+                       return text;
+               },
+
+               /**
+                * Change format to 'parse' and convert message to string
+                *
+                * If jqueryMsg is loaded, this parses the message text from wikitext
+                * (where supported) to HTML
+                *
+                * Otherwise, it is equivalent to plain.
+                *
+                * @return {string} String form of parsed message
+                */
+               parse: function () {
+                       this.format = 'parse';
+                       return this.toString();
+               },
+
+               /**
+                * Change format to 'plain' and convert message to string
+                *
+                * This substitutes parameters, but otherwise does not change the
+                * message text.
+                *
+                * @return {string} String form of plain message
+                */
+               plain: function () {
+                       this.format = 'plain';
+                       return this.toString();
+               },
+
+               /**
+                * Change format to 'text' and convert message to string
+                *
+                * If jqueryMsg is loaded, {{-transformation is done where supported
+                * (such as {{plural:}}, {{gender:}}, {{int:}}).
+                *
+                * Otherwise, it is equivalent to plain
+                *
+                * @return {string} String form of text message
+                */
+               text: function () {
+                       this.format = 'text';
+                       return this.toString();
+               },
+
+               /**
+                * Change the format to 'escaped' and convert message to string
+                *
+                * This is equivalent to using the 'text' format (see #text), then
+                * HTML-escaping the output.
+                *
+                * @return {string} String form of html escaped message
+                */
+               escaped: function () {
+                       this.format = 'escaped';
+                       return this.toString();
+               },
+
+               /**
+                * Check if a message exists
+                *
+                * @see mw.Map#exists
+                * @return {boolean}
+                */
+               exists: function () {
+                       return this.map.exists( this.key );
+               }
+       };
+
+       defineFallbacks();
+
+       /* eslint-disable no-console */
+       log = ( function () {
+               /**
+                * Write a verbose message to the browser's console in debug mode.
+                *
+                * This method is mainly intended for verbose logging. It is a no-op in production mode.
+                * In ResourceLoader debug mode, it will use the browser's console if available, with
+                * fallback to creating a console interface in the DOM and logging messages there.
+                *
+                * See {@link mw.log} for other logging methods.
+                *
+                * @member mw
+                * @param {...string} msg Messages to output to console.
+                */
+               var log = function () {},
+                       console = window.console;
+
+               // Note: Keep list of methods in sync with restoration in mediawiki.log.js
+               // when adding or removing mw.log methods below!
+
+               /**
+                * Collection of methods to help log messages to the console.
+                *
+                * @class mw.log
+                * @singleton
+                */
+
+               /**
+                * Write a message to the browser console's warning channel.
+                *
+                * This method is a no-op in browsers that don't implement the Console API.
+                *
+                * @param {...string} msg Messages to output to console
+                */
+               log.warn = console && console.warn && Function.prototype.bind ?
+                       Function.prototype.bind.call( console.warn, console ) :
+                       $.noop;
+
+               /**
+                * Write a message to the browser console's error channel.
+                *
+                * Most browsers also print a stacktrace when calling this method if the
+                * argument is an Error object.
+                *
+                * This method is a no-op in browsers that don't implement the Console API.
+                *
+                * @since 1.26
+                * @param {Error|...string} msg Messages to output to console
+                */
+               log.error = console && console.error && Function.prototype.bind ?
+                       Function.prototype.bind.call( console.error, console ) :
+                       $.noop;
+
+               /**
+                * Create a property on a host object that, when accessed, will produce
+                * a deprecation warning in the console.
+                *
+                * @param {Object} obj Host object of deprecated property
+                * @param {string} key Name of property to create in `obj`
+                * @param {Mixed} val The value this property should return when accessed
+                * @param {string} [msg] Optional text to include in the deprecation message
+                * @param {string} [logName=key] Optional custom name for the feature.
+                *  This is used instead of `key` in the message and `mw.deprecate` tracking.
+                */
+               log.deprecate = !Object.defineProperty ? function ( obj, key, val ) {
+                       obj[ key ] = val;
+               } : function ( obj, key, val, msg, logName ) {
+                       var logged = new StringSet();
+                       logName = logName || key;
+                       msg = 'Use of "' + logName + '" is deprecated.' + ( msg ? ( ' ' + msg ) : '' );
+                       function uniqueTrace() {
+                               var trace = new Error().stack;
+                               if ( logged.has( trace ) ) {
+                                       return false;
+                               }
+                               logged.add( trace );
+                               return true;
+                       }
+                       // Support: Safari 5.0
+                       // Throws "not supported on DOM Objects" for Node or Element objects (incl. document)
+                       // Safari 4.0 doesn't have this method, and it was fixed in Safari 5.1.
+                       try {
+                               Object.defineProperty( obj, key, {
+                                       configurable: true,
+                                       enumerable: true,
+                                       get: function () {
+                                               if ( uniqueTrace() ) {
+                                                       mw.track( 'mw.deprecate', logName );
+                                                       mw.log.warn( msg );
+                                               }
+                                               return val;
+                                       },
+                                       set: function ( newVal ) {
+                                               if ( uniqueTrace() ) {
+                                                       mw.track( 'mw.deprecate', logName );
+                                                       mw.log.warn( msg );
+                                               }
+                                               val = newVal;
+                                       }
+                               } );
+                       } catch ( err ) {
+                               obj[ key ] = val;
+                       }
+               };
+
+               return log;
+       }() );
+       /* eslint-enable no-console */
+
+       /**
+        * @class mw
+        */
+       mw = {
+               redefineFallbacksForTest: function () {
+                       if ( !window.QUnit ) {
+                               throw new Error( 'Reset not allowed outside unit tests' );
+                       }
+                       defineFallbacks();
+               },
+
+               /**
+                * Get the current time, measured in milliseconds since January 1, 1970 (UTC).
+                *
+                * On browsers that implement the Navigation Timing API, this function will produce floating-point
+                * values with microsecond precision that are guaranteed to be monotonic. On all other browsers,
+                * it will fall back to using `Date`.
+                *
+                * @return {number} Current time
+                */
+               now: mwNow,
+               // mwNow is defined in startup.js
+
+               /**
+                * Format a string. Replace $1, $2 ... $N with positional arguments.
+                *
+                * Used by Message#parser().
+                *
+                * @since 1.25
+                * @param {string} formatString Format string
+                * @param {...Mixed} parameters Values for $N replacements
+                * @return {string} Formatted string
+                */
+               format: function ( formatString ) {
+                       var parameters = slice.call( arguments, 1 );
+                       return formatString.replace( /\$(\d+)/g, function ( str, match ) {
+                               var index = parseInt( match, 10 ) - 1;
+                               return parameters[ index ] !== undefined ? parameters[ index ] : '$' + match;
+                       } );
+               },
+
+               /**
+                * Track an analytic event.
+                *
+                * This method provides a generic means for MediaWiki JavaScript code to capture state
+                * information for analysis. Each logged event specifies a string topic name that describes
+                * the kind of event that it is. Topic names consist of dot-separated path components,
+                * arranged from most general to most specific. Each path component should have a clear and
+                * well-defined purpose.
+                *
+                * Data handlers are registered via `mw.trackSubscribe`, and receive the full set of
+                * events that match their subcription, including those that fired before the handler was
+                * bound.
+                *
+                * @param {string} topic Topic name
+                * @param {Object} [data] Data describing the event, encoded as an object
+                */
+               track: function ( topic, data ) {
+                       trackQueue.push( { topic: topic, timeStamp: mw.now(), data: data } );
+                       trackCallbacks.fire( trackQueue );
+               },
+
+               /**
+                * Register a handler for subset of analytic events, specified by topic.
+                *
+                * Handlers will be called once for each tracked event, including any events that fired before the
+                * handler was registered; 'this' is set to a plain object with a 'timeStamp' property indicating
+                * the exact time at which the event fired, a string 'topic' property naming the event, and a
+                * 'data' property which is an object of event-specific data. The event topic and event data are
+                * also passed to the callback as the first and second arguments, respectively.
+                *
+                * @param {string} topic Handle events whose name starts with this string prefix
+                * @param {Function} callback Handler to call for each matching tracked event
+                * @param {string} callback.topic
+                * @param {Object} [callback.data]
+                */
+               trackSubscribe: function ( topic, callback ) {
+                       var seen = 0;
+                       function handler( trackQueue ) {
+                               var event;
+                               for ( ; seen < trackQueue.length; seen++ ) {
+                                       event = trackQueue[ seen ];
+                                       if ( event.topic.indexOf( topic ) === 0 ) {
+                                               callback.call( event, event.topic, event.data );
+                                       }
+                               }
+                       }
+
+                       trackHandlers.push( [ handler, callback ] );
+
+                       trackCallbacks.add( handler );
+               },
+
+               /**
+                * Stop handling events for a particular handler
+                *
+                * @param {Function} callback
+                */
+               trackUnsubscribe: function ( callback ) {
+                       trackHandlers = $.grep( trackHandlers, function ( fns ) {
+                               if ( fns[ 1 ] === callback ) {
+                                       trackCallbacks.remove( fns[ 0 ] );
+                                       // Ensure the tuple is removed to avoid holding on to closures
+                                       return false;
+                               }
+                               return true;
+                       } );
+               },
+
+               // Expose Map constructor
+               Map: Map,
+
+               // Expose Message constructor
+               Message: Message,
+
+               /**
+                * Map of configuration values.
+                *
+                * Check out [the complete list of configuration values](https://www.mediawiki.org/wiki/Manual:Interface/JavaScript#mw.config)
+                * on mediawiki.org.
+                *
+                * If `$wgLegacyJavaScriptGlobals` is true, this Map will add its values to the
+                * global `window` object.
+                *
+                * @property {mw.Map} config
+                */
+               // Dummy placeholder later assigned in ResourceLoaderStartUpModule
+               config: null,
+
+               /**
+                * Empty object for third-party libraries, for cases where you don't
+                * want to add a new global, or the global is bad and needs containment
+                * or wrapping.
+                *
+                * @property
+                */
+               libs: {},
+
+               /**
+                * Access container for deprecated functionality that can be moved from
+                * from their legacy location and attached to this object (e.g. a global
+                * function that is deprecated and as stop-gap can be exposed through here).
+                *
+                * This was reserved for future use but never ended up being used.
+                *
+                * @deprecated since 1.22 Let deprecated identifiers keep their original name
+                *  and use mw.log#deprecate to create an access container for tracking.
+                * @property
+                */
+               legacy: {},
+
+               /**
+                * Store for messages.
+                *
+                * @property {mw.Map}
+                */
+               messages: new Map(),
+
+               /**
+                * Store for templates associated with a module.
+                *
+                * @property {mw.Map}
+                */
+               templates: new Map(),
+
+               /**
+                * Get a message object.
+                *
+                * Shortcut for `new mw.Message( mw.messages, key, parameters )`.
+                *
+                * @see mw.Message
+                * @param {string} key Key of message to get
+                * @param {...Mixed} parameters Values for $N replacements
+                * @return {mw.Message}
+                */
+               message: function ( key ) {
+                       var parameters = slice.call( arguments, 1 );
+                       return new Message( mw.messages, key, parameters );
+               },
+
+               /**
+                * Get a message string using the (default) 'text' format.
+                *
+                * Shortcut for `mw.message( key, parameters... ).text()`.
+                *
+                * @see mw.Message
+                * @param {string} key Key of message to get
+                * @param {...Mixed} parameters Values for $N replacements
+                * @return {string}
+                */
+               msg: function () {
+                       return mw.message.apply( mw.message, arguments ).toString();
+               },
+
+               // Expose mw.log
+               log: log,
+
+               /**
+                * Client for ResourceLoader server end point.
+                *
+                * This client is in charge of maintaining the module registry and state
+                * machine, initiating network (batch) requests for loading modules, as
+                * well as dependency resolution and execution of source code.
+                *
+                * For more information, refer to
+                * <https://www.mediawiki.org/wiki/ResourceLoader/Features>
+                *
+                * @class mw.loader
+                * @singleton
+                */
+               loader: ( function () {
+
+                       /**
+                        * Fired via mw.track on various resource loading errors.
+                        *
+                        * @event resourceloader_exception
+                        * @param {Error|Mixed} e The error that was thrown. Almost always an Error
+                        *   object, but in theory module code could manually throw something else, and that
+                        *   might also end up here.
+                        * @param {string} [module] Name of the module which caused the error. Omitted if the
+                        *   error is not module-related or the module cannot be easily identified due to
+                        *   batched handling.
+                        * @param {string} source Source of the error. Possible values:
+                        *
+                        *   - style: stylesheet error (only affects old IE where a special style loading method
+                        *     is used)
+                        *   - load-callback: exception thrown by user callback
+                        *   - module-execute: exception thrown by module code
+                        *   - resolve: failed to sort dependencies for a module in mw.loader.load
+                        *   - store-eval: could not evaluate module code cached in localStorage
+                        *   - store-localstorage-init: localStorage or JSON parse error in mw.loader.store.init
+                        *   - store-localstorage-json: JSON conversion error in mw.loader.store.set
+                        *   - store-localstorage-update: localStorage or JSON conversion error in mw.loader.store.update
+                        */
+
+                       /**
+                        * Fired via mw.track on resource loading error conditions.
+                        *
+                        * @event resourceloader_assert
+                        * @param {string} source Source of the error. Possible values:
+                        *
+                        *   - bug-T59567: failed to cache script due to an Opera function -> string conversion
+                        *     bug; see <https://phabricator.wikimedia.org/T59567> for details
+                        */
+
+                       /**
+                        * Mapping of registered modules.
+                        *
+                        * See #implement and #execute for exact details on support for script, style and messages.
+                        *
+                        * Format:
+                        *
+                        *     {
+                        *         'moduleName': {
+                        *             // From mw.loader.register()
+                        *             'version': '########' (hash)
+                        *             'dependencies': ['required.foo', 'bar.also', ...], (or) function () {}
+                        *             'group': 'somegroup', (or) null
+                        *             'source': 'local', (or) 'anotherwiki'
+                        *             'skip': 'return !!window.Example', (or) null
+                        *             'module': export Object
+                        *
+                        *             // Set from execute() or mw.loader.state()
+                        *             'state': 'registered', 'loaded', 'loading', 'ready', 'error', or 'missing'
+                        *
+                        *             // Optionally added at run-time by mw.loader.implement()
+                        *             'skipped': true
+                        *             'script': closure, array of urls, or string
+                        *             'style': { ... } (see #execute)
+                        *             'messages': { 'key': 'value', ... }
+                        *         }
+                        *     }
+                        *
+                        * State machine:
+                        *
+                        * - `registered`:
+                        *    The module is known to the system but not yet required.
+                        *    Meta data is registered via mw.loader#register. Calls to that method are
+                        *    generated server-side by the startup module.
+                        * - `loading`:
+                        *    The module was required through mw.loader (either directly or as dependency of
+                        *    another module). The client will fetch module contents from the server.
+                        *    The contents are then stashed in the registry via mw.loader#implement.
+                        * - `loaded`:
+                        *    The module has been loaded from the server and stashed via mw.loader#implement.
+                        *    If the module has no more dependencies in-flight, the module will be executed
+                        *    immediately. Otherwise execution is deferred, controlled via #handlePending.
+                        * - `executing`:
+                        *    The module is being executed.
+                        * - `ready`:
+                        *    The module has been successfully executed.
+                        * - `error`:
+                        *    The module (or one of its dependencies) produced an error during execution.
+                        * - `missing`:
+                        *    The module was registered client-side and requested, but the server denied knowledge
+                        *    of the module's existence.
+                        *
+                        * @property
+                        * @private
+                        */
+                       var registry = {},
+                               // Mapping of sources, keyed by source-id, values are strings.
+                               //
+                               // Format:
+                               //
+                               //     {
+                               //         'sourceId': 'http://example.org/w/load.php'
+                               //     }
+                               //
+                               sources = {},
+
+                               // For queueModuleScript()
+                               handlingPendingRequests = false,
+                               pendingRequests = [],
+
+                               // List of modules to be loaded
+                               queue = [],
+
+                               /**
+                                * List of callback jobs waiting for modules to be ready.
+                                *
+                                * Jobs are created by #enqueue() and run by #handlePending().
+                                *
+                                * Typically when a job is created for a module, the job's dependencies contain
+                                * both the required module and all its recursive dependencies.
+                                *
+                                * Format:
+                                *
+                                *     {
+                                *         'dependencies': [ module names ],
+                                *         'ready': Function callback
+                                *         'error': Function callback
+                                *     }
+                                *
+                                * @property {Object[]} jobs
+                                * @private
+                                */
+                               jobs = [],
+
+                               // For getMarker()
+                               marker = null,
+
+                               // For addEmbeddedCSS()
+                               cssBuffer = '',
+                               cssBufferTimer = null,
+                               cssCallbacks = $.Callbacks(),
+                               rAF = window.requestAnimationFrame || setTimeout;
+
+                       function getMarker() {
+                               if ( !marker ) {
+                                       // Cache
+                                       marker = document.querySelector( 'meta[name="ResourceLoaderDynamicStyles"]' );
+                                       if ( !marker ) {
+                                               mw.log( 'Create <meta name="ResourceLoaderDynamicStyles"> dynamically' );
+                                               marker = $( '<meta>' ).attr( 'name', 'ResourceLoaderDynamicStyles' ).appendTo( 'head' )[ 0 ];
+                                       }
+                               }
+                               return marker;
+                       }
+
+                       /**
+                        * Create a new style element and add it to the DOM.
+                        *
+                        * @private
+                        * @param {string} text CSS text
+                        * @param {Node} [nextNode] The element where the style tag
+                        *  should be inserted before
+                        * @return {HTMLElement} Reference to the created style element
+                        */
+                       function newStyleTag( text, nextNode ) {
+                               var s = document.createElement( 'style' );
+
+                               s.appendChild( document.createTextNode( text ) );
+                               if ( nextNode && nextNode.parentNode ) {
+                                       nextNode.parentNode.insertBefore( s, nextNode );
+                               } else {
+                                       document.getElementsByTagName( 'head' )[ 0 ].appendChild( s );
+                               }
+
+                               return s;
+                       }
+
+                       /**
+                        * Add a bit of CSS text to the current browser page.
+                        *
+                        * The CSS will be appended to an existing ResourceLoader-created `<style>` tag
+                        * or create a new one based on whether the given `cssText` is safe for extension.
+                        *
+                        * @private
+                        * @param {string} [cssText=cssBuffer] If called without cssText,
+                        *  the internal buffer will be inserted instead.
+                        * @param {Function} [callback]
+                        */
+                       function addEmbeddedCSS( cssText, callback ) {
+                               function fireCallbacks() {
+                                       var oldCallbacks = cssCallbacks;
+                                       // Reset cssCallbacks variable so it's not polluted by any calls to
+                                       // addEmbeddedCSS() from one of the callbacks (T105973)
+                                       cssCallbacks = $.Callbacks();
+                                       oldCallbacks.fire().empty();
+                               }
+
+                               if ( callback ) {
+                                       cssCallbacks.add( callback );
+                               }
+
+                               // Yield once before creating the <style> tag. This lets multiple stylesheets
+                               // accumulate into one buffer, allowing us to reduce how often new stylesheets
+                               // are inserted in the browser. Appending a stylesheet and waiting for the
+                               // browser to repaint is fairly expensive. (T47810)
+                               if ( cssText ) {
+                                       // Don't extend the buffer if the item needs its own stylesheet.
+                                       // Keywords like `@import` are only valid at the start of a stylesheet (T37562).
+                                       if ( !cssBuffer || cssText.slice( 0, '@import'.length ) !== '@import' ) {
+                                               // Linebreak for somewhat distinguishable sections
+                                               cssBuffer += '\n' + cssText;
+                                               if ( !cssBufferTimer ) {
+                                                       cssBufferTimer = rAF( function () {
+                                                               // Wrap in anonymous function that takes no arguments
+                                                               // Support: Firefox < 13
+                                                               // Firefox 12 has non-standard behaviour of passing a number
+                                                               // as first argument to a setTimeout callback.
+                                                               // http://benalman.com/news/2009/07/the-mysterious-firefox-settime/
+                                                               addEmbeddedCSS();
+                                                       } );
+                                               }
+                                               return;
+                                       }
+
+                               // This is a scheduled flush for the buffer
+                               } else {
+                                       cssBufferTimer = null;
+                                       cssText = cssBuffer;
+                                       cssBuffer = '';
+                               }
+
+                               $( newStyleTag( cssText, getMarker() ) );
+
+                               fireCallbacks();
+                       }
+
+                       /**
+                        * @private
+                        * @param {Array} modules List of module names
+                        * @return {string} Hash of concatenated version hashes.
+                        */
+                       function getCombinedVersion( modules ) {
+                               var hashes = modules.map( function ( module ) {
+                                       return registry[ module ].version;
+                               } );
+                               return fnv132( hashes.join( '' ) );
+                       }
+
+                       /**
+                        * Determine whether all dependencies are in state 'ready', which means we may
+                        * execute the module or job now.
+                        *
+                        * @private
+                        * @param {Array} modules Names of modules to be checked
+                        * @return {boolean} True if all modules are in state 'ready', false otherwise
+                        */
+                       function allReady( modules ) {
+                               var i;
+                               for ( i = 0; i < modules.length; i++ ) {
+                                       if ( mw.loader.getState( modules[ i ] ) !== 'ready' ) {
+                                               return false;
+                                       }
+                               }
+                               return true;
+                       }
+
+                       /**
+                        * Determine whether all dependencies are in state 'ready', which means we may
+                        * execute the module or job now.
+                        *
+                        * @private
+                        * @param {Array} modules Names of modules to be checked
+                        * @return {boolean} True if no modules are in state 'error' or 'missing', false otherwise
+                        */
+                       function anyFailed( modules ) {
+                               var i, state;
+                               for ( i = 0; i < modules.length; i++ ) {
+                                       state = mw.loader.getState( modules[ i ] );
+                                       if ( state === 'error' || state === 'missing' ) {
+                                               return true;
+                                       }
+                               }
+                               return false;
+                       }
+
+                       /**
+                        * A module has entered state 'ready', 'error', or 'missing'. Automatically update
+                        * pending jobs and modules that depend upon this module. If the given module failed,
+                        * propagate the 'error' state up the dependency tree. Otherwise, go ahead and execute
+                        * all jobs/modules now having their dependencies satisfied.
+                        *
+                        * Jobs that depend on a failed module, will have their error callback ran (if any).
+                        *
+                        * @private
+                        * @param {string} module Name of module that entered one of the states 'ready', 'error', or 'missing'.
+                        */
+                       function handlePending( module ) {
+                               var j, job, hasErrors, m, stateChange;
+
+                               if ( registry[ module ].state === 'error' || registry[ module ].state === 'missing' ) {
+                                       // If the current module failed, mark all dependent modules also as failed.
+                                       // Iterate until steady-state to propagate the error state upwards in the
+                                       // dependency tree.
+                                       do {
+                                               stateChange = false;
+                                               for ( m in registry ) {
+                                                       if ( registry[ m ].state !== 'error' && registry[ m ].state !== 'missing' ) {
+                                                               if ( anyFailed( registry[ m ].dependencies ) ) {
+                                                                       registry[ m ].state = 'error';
+                                                                       stateChange = true;
+                                                               }
+                                                       }
+                                               }
+                                       } while ( stateChange );
+                               }
+
+                               // Execute all jobs whose dependencies are either all satisfied or contain at least one failed module.
+                               for ( j = 0; j < jobs.length; j++ ) {
+                                       hasErrors = anyFailed( jobs[ j ].dependencies );
+                                       if ( hasErrors || allReady( jobs[ j ].dependencies ) ) {
+                                               // All dependencies satisfied, or some have errors
+                                               job = jobs[ j ];
+                                               jobs.splice( j, 1 );
+                                               j -= 1;
+                                               try {
+                                                       if ( hasErrors ) {
+                                                               if ( typeof job.error === 'function' ) {
+                                                                       job.error( new Error( 'Module ' + module + ' has failed dependencies' ), [ module ] );
+                                                               }
+                                                       } else {
+                                                               if ( typeof job.ready === 'function' ) {
+                                                                       job.ready();
+                                                               }
+                                                       }
+                                               } catch ( e ) {
+                                                       // A user-defined callback raised an exception.
+                                                       // Swallow it to protect our state machine!
+                                                       mw.track( 'resourceloader.exception', { exception: e, module: module, source: 'load-callback' } );
+                                               }
+                                       }
+                               }
+
+                               if ( registry[ module ].state === 'ready' ) {
+                                       // The current module became 'ready'. Set it in the module store, and recursively execute all
+                                       // dependent modules that are loaded and now have all dependencies satisfied.
+                                       mw.loader.store.set( module, registry[ module ] );
+                                       for ( m in registry ) {
+                                               if ( registry[ m ].state === 'loaded' && allReady( registry[ m ].dependencies ) ) {
+                                                       execute( m );
+                                               }
+                                       }
+                               }
+                       }
+
+                       /**
+                        * Resolve dependencies and detect circular references.
+                        *
+                        * @private
+                        * @param {string} module Name of the top-level module whose dependencies shall be
+                        *  resolved and sorted.
+                        * @param {Array} resolved Returns a topological sort of the given module and its
+                        *  dependencies, such that later modules depend on earlier modules. The array
+                        *  contains the module names. If the array contains already some module names,
+                        *  this function appends its result to the pre-existing array.
+                        * @param {StringSet} [unresolved] Used to track the current dependency
+                        *  chain, and to report loops in the dependency graph.
+                        * @throws {Error} If any unregistered module or a dependency loop is encountered
+                        */
+                       function sortDependencies( module, resolved, unresolved ) {
+                               var i, deps, skip;
+
+                               if ( !hasOwn.call( registry, module ) ) {
+                                       throw new Error( 'Unknown dependency: ' + module );
+                               }
+
+                               if ( registry[ module ].skip !== null ) {
+                                       // eslint-disable-next-line no-new-func
+                                       skip = new Function( registry[ module ].skip );
+                                       registry[ module ].skip = null;
+                                       if ( skip() ) {
+                                               registry[ module ].skipped = true;
+                                               registry[ module ].dependencies = [];
+                                               registry[ module ].state = 'ready';
+                                               handlePending( module );
+                                               return;
+                                       }
+                               }
+
+                               // Resolves dynamic loader function and replaces it with its own results
+                               if ( typeof registry[ module ].dependencies === 'function' ) {
+                                       registry[ module ].dependencies = registry[ module ].dependencies();
+                                       // Ensures the module's dependencies are always in an array
+                                       if ( typeof registry[ module ].dependencies !== 'object' ) {
+                                               registry[ module ].dependencies = [ registry[ module ].dependencies ];
+                                       }
+                               }
+                               if ( $.inArray( module, resolved ) !== -1 ) {
+                                       // Module already resolved; nothing to do
+                                       return;
+                               }
+                               // Create unresolved if not passed in
+                               if ( !unresolved ) {
+                                       unresolved = new StringSet();
+                               }
+                               // Tracks down dependencies
+                               deps = registry[ module ].dependencies;
+                               for ( i = 0; i < deps.length; i++ ) {
+                                       if ( $.inArray( deps[ i ], resolved ) === -1 ) {
+                                               if ( unresolved.has( deps[ i ] ) ) {
+                                                       throw new Error( mw.format(
+                                                               'Circular reference detected: $1 -> $2',
+                                                               module,
+                                                               deps[ i ]
+                                                       ) );
+                                               }
+
+                                               unresolved.add( module );
+                                               sortDependencies( deps[ i ], resolved, unresolved );
+                                       }
+                               }
+                               resolved.push( module );
+                       }
+
+                       /**
+                        * Get names of module that a module depends on, in their proper dependency order.
+                        *
+                        * @private
+                        * @param {string[]} modules Array of string module names
+                        * @return {Array} List of dependencies, including 'module'.
+                        * @throws {Error} If an unregistered module or a dependency loop is encountered
+                        */
+                       function resolve( modules ) {
+                               var i, resolved = [];
+                               for ( i = 0; i < modules.length; i++ ) {
+                                       sortDependencies( modules[ i ], resolved );
+                               }
+                               return resolved;
+                       }
+
+                       /**
+                        * Like #resolve(), except it will silently ignore modules that
+                        * are missing or have missing dependencies.
+                        *
+                        * @private
+                        * @param {string[]} modules Array of string module names
+                        * @return {Array} List of dependencies.
+                        */
+                       function resolveStubbornly( modules ) {
+                               var i, saved, resolved = [];
+                               for ( i = 0; i < modules.length; i++ ) {
+                                       saved = resolved.slice();
+                                       try {
+                                               sortDependencies( modules[ i ], resolved );
+                                       } catch ( err ) {
+                                               // This module is unknown or has unknown dependencies.
+                                               // Undo any incomplete resolutions made and keep going.
+                                               resolved = saved;
+                                               mw.track( 'resourceloader.exception', {
+                                                       exception: err,
+                                                       source: 'resolve'
+                                               } );
+                                       }
+                               }
+                               return resolved;
+                       }
+
+                       /**
+                        * Load and execute a script.
+                        *
+                        * @private
+                        * @param {string} src URL to script, will be used as the src attribute in the script tag
+                        * @return {jQuery.Promise}
+                        */
+                       function addScript( src ) {
+                               return $.ajax( {
+                                       url: src,
+                                       dataType: 'script',
+                                       // Force jQuery behaviour to be for crossDomain. Otherwise jQuery would use
+                                       // XHR for a same domain request instead of <script>, which changes the request
+                                       // headers (potentially missing a cache hit), and reduces caching in general
+                                       // since browsers cache XHR much less (if at all). And XHR means we retrieve
+                                       // text, so we'd need to $.globalEval, which then messes up line numbers.
+                                       crossDomain: true,
+                                       cache: true
+                               } );
+                       }
+
+                       /**
+                        * Queue the loading and execution of a script for a particular module.
+                        *
+                        * @private
+                        * @param {string} src URL of the script
+                        * @param {string} [moduleName] Name of currently executing module
+                        * @return {jQuery.Promise}
+                        */
+                       function queueModuleScript( src, moduleName ) {
+                               var r = $.Deferred();
+
+                               pendingRequests.push( function () {
+                                       if ( moduleName && hasOwn.call( registry, moduleName ) ) {
+                                               // Emulate runScript() part of execute()
+                                               window.require = mw.loader.require;
+                                               window.module = registry[ moduleName ].module;
+                                       }
+                                       addScript( src ).always( function () {
+                                               // 'module.exports' should not persist after the file is executed to
+                                               // avoid leakage to unrelated code. 'require' should be kept, however,
+                                               // as asynchronous access to 'require' is allowed and expected. (T144879)
+                                               delete window.module;
+                                               r.resolve();
+
+                                               // Start the next one (if any)
+                                               if ( pendingRequests[ 0 ] ) {
+                                                       pendingRequests.shift()();
+                                               } else {
+                                                       handlingPendingRequests = false;
+                                               }
+                                       } );
+                               } );
+                               if ( !handlingPendingRequests && pendingRequests[ 0 ] ) {
+                                       handlingPendingRequests = true;
+                                       pendingRequests.shift()();
+                               }
+                               return r.promise();
+                       }
+
+                       /**
+                        * Utility function for execute()
+                        *
+                        * @ignore
+                        * @param {string} [media] Media attribute
+                        * @param {string} url URL
+                        */
+                       function addLink( media, url ) {
+                               var el = document.createElement( 'link' );
+
+                               el.rel = 'stylesheet';
+                               if ( media && media !== 'all' ) {
+                                       el.media = media;
+                               }
+                               // If you end up here from an IE exception "SCRIPT: Invalid property value.",
+                               // see #addEmbeddedCSS, T33676, T43331, and T49277 for details.
+                               el.href = url;
+
+                               $( getMarker() ).before( el );
+                       }
+
+                       /**
+                        * Executes a loaded module, making it ready to use
+                        *
+                        * @private
+                        * @param {string} module Module name to execute
+                        */
+                       function execute( module ) {
+                               var key, value, media, i, urls, cssHandle, checkCssHandles, runScript,
+                                       cssHandlesRegistered = false;
+
+                               if ( !hasOwn.call( registry, module ) ) {
+                                       throw new Error( 'Module has not been registered yet: ' + module );
+                               }
+                               if ( registry[ module ].state !== 'loaded' ) {
+                                       throw new Error( 'Module in state "' + registry[ module ].state + '" may not be executed: ' + module );
+                               }
+
+                               registry[ module ].state = 'executing';
+
+                               runScript = function () {
+                                       var script, markModuleReady, nestedAddScript;
+
+                                       script = registry[ module ].script;
+                                       markModuleReady = function () {
+                                               registry[ module ].state = 'ready';
+                                               handlePending( module );
+                                       };
+                                       nestedAddScript = function ( arr, callback, i ) {
+                                               // Recursively call queueModuleScript() in its own callback
+                                               // for each element of arr.
+                                               if ( i >= arr.length ) {
+                                                       // We're at the end of the array
+                                                       callback();
+                                                       return;
+                                               }
+
+                                               queueModuleScript( arr[ i ], module ).always( function () {
+                                                       nestedAddScript( arr, callback, i + 1 );
+                                               } );
+                                       };
+
+                                       try {
+                                               if ( Array.isArray( script ) ) {
+                                                       nestedAddScript( script, markModuleReady, 0 );
+                                               } else if ( typeof script === 'function' ) {
+                                                       // Pass jQuery twice so that the signature of the closure which wraps
+                                                       // the script can bind both '$' and 'jQuery'.
+                                                       script( $, $, mw.loader.require, registry[ module ].module );
+                                                       markModuleReady();
+
+                                               } else if ( typeof script === 'string' ) {
+                                                       // Site and user modules are legacy scripts that run in the global scope.
+                                                       // This is transported as a string instead of a function to avoid needing
+                                                       // to use string manipulation to undo the function wrapper.
+                                                       $.globalEval( script );
+                                                       markModuleReady();
+
+                                               } else {
+                                                       // Module without script
+                                                       markModuleReady();
+                                               }
+                                       } catch ( e ) {
+                                               // Use mw.track instead of mw.log because these errors are common in production mode
+                                               // (e.g. undefined variable), and mw.log is only enabled in debug mode.
+                                               registry[ module ].state = 'error';
+                                               mw.track( 'resourceloader.exception', { exception: e, module: module, source: 'module-execute' } );
+                                               handlePending( module );
+                                       }
+                               };
+
+                               // Add localizations to message system
+                               if ( registry[ module ].messages ) {
+                                       mw.messages.set( registry[ module ].messages );
+                               }
+
+                               // Initialise templates
+                               if ( registry[ module ].templates ) {
+                                       mw.templates.set( module, registry[ module ].templates );
+                               }
+
+                               // Make sure we don't run the scripts until all stylesheet insertions have completed.
+                               ( function () {
+                                       var pending = 0;
+                                       checkCssHandles = function () {
+                                               // cssHandlesRegistered ensures we don't take off too soon, e.g. when
+                                               // one of the cssHandles is fired while we're still creating more handles.
+                                               if ( cssHandlesRegistered && pending === 0 && runScript ) {
+                                                       if ( module === 'user' ) {
+                                                               // Implicit dependency on the site module. Not real dependency because
+                                                               // it should run after 'site' regardless of whether it succeeds or fails.
+                                                               mw.loader.using( [ 'site' ] ).always( runScript );
+                                                       } else {
+                                                               runScript();
+                                                       }
+                                                       runScript = undefined; // Revoke
+                                               }
+                                       };
+                                       cssHandle = function () {
+                                               var check = checkCssHandles;
+                                               pending++;
+                                               return function () {
+                                                       if ( check ) {
+                                                               pending--;
+                                                               check();
+                                                               check = undefined; // Revoke
+                                                       }
+                                               };
+                                       };
+                               }() );
+
+                               // Process styles (see also mw.loader.implement)
+                               // * back-compat: { <media>: css }
+                               // * back-compat: { <media>: [url, ..] }
+                               // * { "css": [css, ..] }
+                               // * { "url": { <media>: [url, ..] } }
+                               if ( registry[ module ].style ) {
+                                       for ( key in registry[ module ].style ) {
+                                               value = registry[ module ].style[ key ];
+                                               media = undefined;
+
+                                               if ( key !== 'url' && key !== 'css' ) {
+                                                       // Backwards compatibility, key is a media-type
+                                                       if ( typeof value === 'string' ) {
+                                                               // back-compat: { <media>: css }
+                                                               // Ignore 'media' because it isn't supported (nor was it used).
+                                                               // Strings are pre-wrapped in "@media". The media-type was just ""
+                                                               // (because it had to be set to something).
+                                                               // This is one of the reasons why this format is no longer used.
+                                                               addEmbeddedCSS( value, cssHandle() );
+                                                       } else {
+                                                               // back-compat: { <media>: [url, ..] }
+                                                               media = key;
+                                                               key = 'bc-url';
+                                                       }
+                                               }
+
+                                               // Array of css strings in key 'css',
+                                               // or back-compat array of urls from media-type
+                                               if ( Array.isArray( value ) ) {
+                                                       for ( i = 0; i < value.length; i++ ) {
+                                                               if ( key === 'bc-url' ) {
+                                                                       // back-compat: { <media>: [url, ..] }
+                                                                       addLink( media, value[ i ] );
+                                                               } else if ( key === 'css' ) {
+                                                                       // { "css": [css, ..] }
+                                                                       addEmbeddedCSS( value[ i ], cssHandle() );
+                                                               }
+                                                       }
+                                               // Not an array, but a regular object
+                                               // Array of urls inside media-type key
+                                               } else if ( typeof value === 'object' ) {
+                                                       // { "url": { <media>: [url, ..] } }
+                                                       for ( media in value ) {
+                                                               urls = value[ media ];
+                                                               for ( i = 0; i < urls.length; i++ ) {
+                                                                       addLink( media, urls[ i ] );
+                                                               }
+                                                       }
+                                               }
+                                       }
+                               }
+
+                               // Kick off.
+                               cssHandlesRegistered = true;
+                               checkCssHandles();
+                       }
+
+                       /**
+                        * Add one or more modules to the module load queue.
+                        *
+                        * See also #work().
+                        *
+                        * @private
+                        * @param {string|string[]} dependencies Module name or array of string module names
+                        * @param {Function} [ready] Callback to execute when all dependencies are ready
+                        * @param {Function} [error] Callback to execute when any dependency fails
+                        */
+                       function enqueue( dependencies, ready, error ) {
+                               // Allow calling by single module name
+                               if ( typeof dependencies === 'string' ) {
+                                       dependencies = [ dependencies ];
+                               }
+
+                               // Add ready and error callbacks if they were given
+                               if ( ready !== undefined || error !== undefined ) {
+                                       jobs.push( {
+                                               // Narrow down the list to modules that are worth waiting for
+                                               dependencies: $.grep( dependencies, function ( module ) {
+                                                       var state = mw.loader.getState( module );
+                                                       return state === 'registered' || state === 'loaded' || state === 'loading' || state === 'executing';
+                                               } ),
+                                               ready: ready,
+                                               error: error
+                                       } );
+                               }
+
+                               $.each( dependencies, function ( idx, module ) {
+                                       var state = mw.loader.getState( module );
+                                       // Only queue modules that are still in the initial 'registered' state
+                                       // (not ones already loading, ready or error).
+                                       if ( state === 'registered' && $.inArray( module, queue ) === -1 ) {
+                                               // Private modules must be embedded in the page. Don't bother queuing
+                                               // these as the server will deny them anyway (T101806).
+                                               if ( registry[ module ].group === 'private' ) {
+                                                       registry[ module ].state = 'error';
+                                                       handlePending( module );
+                                                       return;
+                                               }
+                                               queue.push( module );
+                                       }
+                               } );
+
+                               mw.loader.work();
+                       }
+
+                       function sortQuery( o ) {
+                               var key,
+                                       sorted = {},
+                                       a = [];
+
+                               for ( key in o ) {
+                                       a.push( key );
+                               }
+                               a.sort();
+                               for ( key = 0; key < a.length; key++ ) {
+                                       sorted[ a[ key ] ] = o[ a[ key ] ];
+                               }
+                               return sorted;
+                       }
+
+                       /**
+                        * Converts a module map of the form { foo: [ 'bar', 'baz' ], bar: [ 'baz, 'quux' ] }
+                        * to a query string of the form foo.bar,baz|bar.baz,quux
+                        *
+                        * @private
+                        * @param {Object} moduleMap Module map
+                        * @return {string} Module query string
+                        */
+                       function buildModulesString( moduleMap ) {
+                               var p, prefix,
+                                       arr = [];
+
+                               for ( prefix in moduleMap ) {
+                                       p = prefix === '' ? '' : prefix + '.';
+                                       arr.push( p + moduleMap[ prefix ].join( ',' ) );
+                               }
+                               return arr.join( '|' );
+                       }
+
+                       /**
+                        * Make a network request to load modules from the server.
+                        *
+                        * @private
+                        * @param {Object} moduleMap Module map, see #buildModulesString
+                        * @param {Object} currReqBase Object with other parameters (other than 'modules') to use in the request
+                        * @param {string} sourceLoadScript URL of load.php
+                        */
+                       function doRequest( moduleMap, currReqBase, sourceLoadScript ) {
+                               // Optimisation: Inherit (Object.create), not copy ($.extend)
+                               var query = Object.create( currReqBase );
+                               query.modules = buildModulesString( moduleMap );
+                               query = sortQuery( query );
+                               addScript( sourceLoadScript + '?' + $.param( query ) );
+                       }
+
+                       /**
+                        * Resolve indexed dependencies.
+                        *
+                        * ResourceLoader uses an optimization to save space which replaces module names in
+                        * dependency lists with the index of that module within the array of module
+                        * registration data if it exists. The benefit is a significant reduction in the data
+                        * size of the startup module. This function changes those dependency lists back to
+                        * arrays of strings.
+                        *
+                        * @private
+                        * @param {Array} modules Modules array
+                        */
+                       function resolveIndexedDependencies( modules ) {
+                               var i, j, deps;
+                               function resolveIndex( dep ) {
+                                       return typeof dep === 'number' ? modules[ dep ][ 0 ] : dep;
+                               }
+                               for ( i = 0; i < modules.length; i++ ) {
+                                       deps = modules[ i ][ 2 ];
+                                       if ( deps ) {
+                                               for ( j = 0; j < deps.length; j++ ) {
+                                                       deps[ j ] = resolveIndex( deps[ j ] );
+                                               }
+                                       }
+                               }
+                       }
+
+                       /**
+                        * Create network requests for a batch of modules.
+                        *
+                        * This is an internal method for #work(). This must not be called directly
+                        * unless the modules are already registered, and no request is in progress,
+                        * and the module state has already been set to `loading`.
+                        *
+                        * @private
+                        * @param {string[]} batch
+                        */
+                       function batchRequest( batch ) {
+                               var reqBase, splits, maxQueryLength, b, bSource, bGroup, bSourceGroup,
+                                       source, group, i, modules, sourceLoadScript,
+                                       currReqBase, currReqBaseLength, moduleMap, l,
+                                       lastDotIndex, prefix, suffix, bytesAdded;
+
+                               if ( !batch.length ) {
+                                       return;
+                               }
+
+                               // Always order modules alphabetically to help reduce cache
+                               // misses for otherwise identical content.
+                               batch.sort();
+
+                               // Build a list of query parameters common to all requests
+                               reqBase = {
+                                       skin: mw.config.get( 'skin' ),
+                                       lang: mw.config.get( 'wgUserLanguage' ),
+                                       debug: mw.config.get( 'debug' )
+                               };
+                               maxQueryLength = mw.config.get( 'wgResourceLoaderMaxQueryLength', 2000 );
+
+                               // Split module list by source and by group.
+                               splits = {};
+                               for ( b = 0; b < batch.length; b++ ) {
+                                       bSource = registry[ batch[ b ] ].source;
+                                       bGroup = registry[ batch[ b ] ].group;
+                                       if ( !hasOwn.call( splits, bSource ) ) {
+                                               splits[ bSource ] = {};
+                                       }
+                                       if ( !hasOwn.call( splits[ bSource ], bGroup ) ) {
+                                               splits[ bSource ][ bGroup ] = [];
+                                       }
+                                       bSourceGroup = splits[ bSource ][ bGroup ];
+                                       bSourceGroup.push( batch[ b ] );
+                               }
+
+                               for ( source in splits ) {
+
+                                       sourceLoadScript = sources[ source ];
+
+                                       for ( group in splits[ source ] ) {
+
+                                               // Cache access to currently selected list of
+                                               // modules for this group from this source.
+                                               modules = splits[ source ][ group ];
+
+                                               // Optimisation: Inherit (Object.create), not copy ($.extend)
+                                               currReqBase = Object.create( reqBase );
+                                               currReqBase.version = getCombinedVersion( modules );
+
+                                               // For user modules append a user name to the query string.
+                                               if ( group === 'user' && mw.config.get( 'wgUserName' ) !== null ) {
+                                                       currReqBase.user = mw.config.get( 'wgUserName' );
+                                               }
+                                               currReqBaseLength = $.param( currReqBase ).length;
+                                               // We may need to split up the request to honor the query string length limit,
+                                               // so build it piece by piece.
+                                               l = currReqBaseLength + 9; // '&modules='.length == 9
+
+                                               moduleMap = {}; // { prefix: [ suffixes ] }
+
+                                               for ( i = 0; i < modules.length; i++ ) {
+                                                       // Determine how many bytes this module would add to the query string
+                                                       lastDotIndex = modules[ i ].lastIndexOf( '.' );
+
+                                                       // If lastDotIndex is -1, substr() returns an empty string
+                                                       prefix = modules[ i ].substr( 0, lastDotIndex );
+                                                       suffix = modules[ i ].slice( lastDotIndex + 1 );
+
+                                                       bytesAdded = hasOwn.call( moduleMap, prefix ) ?
+                                                               suffix.length + 3 : // '%2C'.length == 3
+                                                               modules[ i ].length + 3; // '%7C'.length == 3
+
+                                                       // If the url would become too long, create a new one,
+                                                       // but don't create empty requests
+                                                       if ( maxQueryLength > 0 && !$.isEmptyObject( moduleMap ) && l + bytesAdded > maxQueryLength ) {
+                                                               // This url would become too long, create a new one, and start the old one
+                                                               doRequest( moduleMap, currReqBase, sourceLoadScript );
+                                                               moduleMap = {};
+                                                               l = currReqBaseLength + 9;
+                                                               mw.track( 'resourceloader.splitRequest', { maxQueryLength: maxQueryLength } );
+                                                       }
+                                                       if ( !hasOwn.call( moduleMap, prefix ) ) {
+                                                               moduleMap[ prefix ] = [];
+                                                       }
+                                                       moduleMap[ prefix ].push( suffix );
+                                                       l += bytesAdded;
+                                               }
+                                               // If there's anything left in moduleMap, request that too
+                                               if ( !$.isEmptyObject( moduleMap ) ) {
+                                                       doRequest( moduleMap, currReqBase, sourceLoadScript );
+                                               }
+                                       }
+                               }
+                       }
+
+                       /**
+                        * @private
+                        * @param {string[]} implementations Array containing pieces of JavaScript code in the
+                        *  form of calls to mw.loader#implement().
+                        * @param {Function} cb Callback in case of failure
+                        * @param {Error} cb.err
+                        */
+                       function asyncEval( implementations, cb ) {
+                               if ( !implementations.length ) {
+                                       return;
+                               }
+                               mw.requestIdleCallback( function () {
+                                       try {
+                                               $.globalEval( implementations.join( ';' ) );
+                                       } catch ( err ) {
+                                               cb( err );
+                                       }
+                               } );
+                       }
+
+                       /**
+                        * Make a versioned key for a specific module.
+                        *
+                        * @private
+                        * @param {string} module Module name
+                        * @return {string|null} Module key in format '`[name]@[version]`',
+                        *  or null if the module does not exist
+                        */
+                       function getModuleKey( module ) {
+                               return hasOwn.call( registry, module ) ?
+                                       ( module + '@' + registry[ module ].version ) : null;
+                       }
+
+                       /**
+                        * @private
+                        * @param {string} key Module name or '`[name]@[version]`'
+                        * @return {Object}
+                        */
+                       function splitModuleKey( key ) {
+                               var index = key.indexOf( '@' );
+                               if ( index === -1 ) {
+                                       return { name: key };
+                               }
+                               return {
+                                       name: key.slice( 0, index ),
+                                       version: key.slice( index + 1 )
+                               };
+                       }
+
+                       /* Public Members */
+                       return {
+                               /**
+                                * The module registry is exposed as an aid for debugging and inspecting page
+                                * state; it is not a public interface for modifying the registry.
+                                *
+                                * @see #registry
+                                * @property
+                                * @private
+                                */
+                               moduleRegistry: registry,
+
+                               /**
+                                * @inheritdoc #newStyleTag
+                                * @method
+                                */
+                               addStyleTag: newStyleTag,
+
+                               /**
+                                * Start loading of all queued module dependencies.
+                                *
+                                * @protected
+                                */
+                               work: function () {
+                                       var q, batch, implementations, sourceModules;
+
+                                       batch = [];
+
+                                       // Appends a list of modules from the queue to the batch
+                                       for ( q = 0; q < queue.length; q++ ) {
+                                               // Only load modules which are registered
+                                               if ( hasOwn.call( registry, queue[ q ] ) && registry[ queue[ q ] ].state === 'registered' ) {
+                                                       // Prevent duplicate entries
+                                                       if ( $.inArray( queue[ q ], batch ) === -1 ) {
+                                                               batch.push( queue[ q ] );
+                                                               // Mark registered modules as loading
+                                                               registry[ queue[ q ] ].state = 'loading';
+                                                       }
+                                               }
+                                       }
+
+                                       // Now that the queue has been processed into a batch, clear the queue.
+                                       // This MUST happen before we initiate any eval or network request. Otherwise,
+                                       // it is possible for a cached script to instantly trigger the same work queue
+                                       // again; all before we've cleared it causing each request to include modules
+                                       // which are already loaded.
+                                       queue = [];
+
+                                       if ( !batch.length ) {
+                                               return;
+                                       }
+
+                                       mw.loader.store.init();
+                                       if ( mw.loader.store.enabled ) {
+                                               implementations = [];
+                                               sourceModules = [];
+                                               batch = $.grep( batch, function ( module ) {
+                                                       var implementation = mw.loader.store.get( module );
+                                                       if ( implementation ) {
+                                                               implementations.push( implementation );
+                                                               sourceModules.push( module );
+                                                               return false;
+                                                       }
+                                                       return true;
+                                               } );
+                                               asyncEval( implementations, function ( err ) {
+                                                       var failed;
+                                                       // Not good, the cached mw.loader.implement calls failed! This should
+                                                       // never happen, barring ResourceLoader bugs, browser bugs and PEBKACs.
+                                                       // Depending on how corrupt the string is, it is likely that some
+                                                       // modules' implement() succeeded while the ones after the error will
+                                                       // never run and leave their modules in the 'loading' state forever.
+                                                       mw.loader.store.stats.failed++;
+
+                                                       // Since this is an error not caused by an individual module but by
+                                                       // something that infected the implement call itself, don't take any
+                                                       // risks and clear everything in this cache.
+                                                       mw.loader.store.clear();
+
+                                                       mw.track( 'resourceloader.exception', { exception: err, source: 'store-eval' } );
+                                                       // Re-add the failed ones that are still pending back to the batch
+                                                       failed = $.grep( sourceModules, function ( module ) {
+                                                               return registry[ module ].state === 'loading';
+                                                       } );
+                                                       batchRequest( failed );
+                                               } );
+                                       }
+
+                                       batchRequest( batch );
+                               },
+
+                               /**
+                                * Register a source.
+                                *
+                                * The #work() method will use this information to split up requests by source.
+                                *
+                                *     mw.loader.addSource( 'mediawikiwiki', '//www.mediawiki.org/w/load.php' );
+                                *
+                                * @param {string|Object} id Source ID, or object mapping ids to load urls
+                                * @param {string} loadUrl Url to a load.php end point
+                                * @throws {Error} If source id is already registered
+                                */
+                               addSource: function ( id, loadUrl ) {
+                                       var source;
+                                       // Allow multiple additions
+                                       if ( typeof id === 'object' ) {
+                                               for ( source in id ) {
+                                                       mw.loader.addSource( source, id[ source ] );
+                                               }
+                                               return;
+                                       }
+
+                                       if ( hasOwn.call( sources, id ) ) {
+                                               throw new Error( 'source already registered: ' + id );
+                                       }
+
+                                       sources[ id ] = loadUrl;
+                               },
+
+                               /**
+                                * Register a module, letting the system know about it and its properties.
+                                *
+                                * The startup modules contain calls to this method.
+                                *
+                                * When using multiple module registration by passing an array, dependencies that
+                                * are specified as references to modules within the array will be resolved before
+                                * the modules are registered.
+                                *
+                                * @param {string|Array} module Module name or array of arrays, each containing
+                                *  a list of arguments compatible with this method
+                                * @param {string|number} version Module version hash (falls backs to empty string)
+                                *  Can also be a number (timestamp) for compatibility with MediaWiki 1.25 and earlier.
+                                * @param {string|Array|Function} dependencies One string or array of strings of module
+                                *  names on which this module depends, or a function that returns that array.
+                                * @param {string} [group=null] Group which the module is in
+                                * @param {string} [source='local'] Name of the source
+                                * @param {string} [skip=null] Script body of the skip function
+                                */
+                               register: function ( module, version, dependencies, group, source, skip ) {
+                                       var i, deps;
+                                       // Allow multiple registration
+                                       if ( typeof module === 'object' ) {
+                                               resolveIndexedDependencies( module );
+                                               for ( i = 0; i < module.length; i++ ) {
+                                                       // module is an array of module names
+                                                       if ( typeof module[ i ] === 'string' ) {
+                                                               mw.loader.register( module[ i ] );
+                                                       // module is an array of arrays
+                                                       } else if ( typeof module[ i ] === 'object' ) {
+                                                               mw.loader.register.apply( mw.loader, module[ i ] );
+                                                       }
+                                               }
+                                               return;
+                                       }
+                                       if ( hasOwn.call( registry, module ) ) {
+                                               throw new Error( 'module already registered: ' + module );
+                                       }
+                                       if ( typeof dependencies === 'string' ) {
+                                               // A single module name
+                                               deps = [ dependencies ];
+                                       } else if ( typeof dependencies === 'object' || typeof dependencies === 'function' ) {
+                                               // Array of module names or a function that returns an array
+                                               deps = dependencies;
+                                       }
+                                       // List the module as registered
+                                       registry[ module ] = {
+                                               // Exposed to execute() for mw.loader.implement() closures.
+                                               // Import happens via require().
+                                               module: {
+                                                       exports: {}
+                                               },
+                                               version: version !== undefined ? String( version ) : '',
+                                               dependencies: deps || [],
+                                               group: typeof group === 'string' ? group : null,
+                                               source: typeof source === 'string' ? source : 'local',
+                                               state: 'registered',
+                                               skip: typeof skip === 'string' ? skip : null
+                                       };
+                               },
+
+                               /**
+                                * Implement a module given the components that make up the module.
+                                *
+                                * When #load() or #using() requests one or more modules, the server
+                                * response contain calls to this function.
+                                *
+                                * @param {string} module Name of module and current module version. Formatted
+                                *  as '`[name]@[version]`". This version should match the requested version
+                                *  (from #batchRequest and #registry). This avoids race conditions (T117587).
+                                *  For back-compat with MediaWiki 1.27 and earlier, the version may be omitted.
+                                * @param {Function|Array|string} [script] Function with module code, list of URLs
+                                *  to load via `<script src>`, or string of module code for `$.globalEval()`.
+                                * @param {Object} [style] Should follow one of the following patterns:
+                                *
+                                *     { "css": [css, ..] }
+                                *     { "url": { <media>: [url, ..] } }
+                                *
+                                * And for backwards compatibility (needs to be supported forever due to caching):
+                                *
+                                *     { <media>: css }
+                                *     { <media>: [url, ..] }
+                                *
+                                * The reason css strings are not concatenated anymore is T33676. We now check
+                                * whether it's safe to extend the stylesheet.
+                                *
+                                * @protected
+                                * @param {Object} [messages] List of key/value pairs to be added to mw#messages.
+                                * @param {Object} [templates] List of key/value pairs to be added to mw#templates.
+                                */
+                               implement: function ( module, script, style, messages, templates ) {
+                                       var split = splitModuleKey( module ),
+                                               name = split.name,
+                                               version = split.version;
+                                       // Automatically register module
+                                       if ( !hasOwn.call( registry, name ) ) {
+                                               mw.loader.register( name );
+                                       }
+                                       // Check for duplicate implementation
+                                       if ( hasOwn.call( registry, name ) && registry[ name ].script !== undefined ) {
+                                               throw new Error( 'module already implemented: ' + name );
+                                       }
+                                       if ( version ) {
+                                               // Without this reset, if there is a version mismatch between the
+                                               // requested and received module version, then mw.loader.store would
+                                               // cache the response under the requested key. Thus poisoning the cache
+                                               // indefinitely with a stale value. (T117587)
+                                               registry[ name ].version = version;
+                                       }
+                                       // Attach components
+                                       registry[ name ].script = script || null;
+                                       registry[ name ].style = style || null;
+                                       registry[ name ].messages = messages || null;
+                                       registry[ name ].templates = templates || null;
+                                       // The module may already have been marked as erroneous
+                                       if ( $.inArray( registry[ name ].state, [ 'error', 'missing' ] ) === -1 ) {
+                                               registry[ name ].state = 'loaded';
+                                               if ( allReady( registry[ name ].dependencies ) ) {
+                                                       execute( name );
+                                               }
+                                       }
+                               },
+
+                               /**
+                                * Execute a function as soon as one or more required modules are ready.
+                                *
+                                * Example of inline dependency on OOjs:
+                                *
+                                *     mw.loader.using( 'oojs', function () {
+                                *         OO.compare( [ 1 ], [ 1 ] );
+                                *     } );
+                                *
+                                * Since MediaWiki 1.23 this also returns a promise.
+                                *
+                                * Since MediaWiki 1.28 the promise is resolved with a `require` function.
+                                *
+                                * @param {string|Array} dependencies Module name or array of modules names the
+                                *  callback depends on to be ready before executing
+                                * @param {Function} [ready] Callback to execute when all dependencies are ready
+                                * @param {Function} [error] Callback to execute if one or more dependencies failed
+                                * @return {jQuery.Promise} With a `require` function
+                                */
+                               using: function ( dependencies, ready, error ) {
+                                       var deferred = $.Deferred();
+
+                                       // Allow calling with a single dependency as a string
+                                       if ( typeof dependencies === 'string' ) {
+                                               dependencies = [ dependencies ];
+                                       }
+
+                                       if ( ready ) {
+                                               deferred.done( ready );
+                                       }
+                                       if ( error ) {
+                                               deferred.fail( error );
+                                       }
+
+                                       try {
+                                               // Resolve entire dependency map
+                                               dependencies = resolve( dependencies );
+                                       } catch ( e ) {
+                                               return deferred.reject( e ).promise();
+                                       }
+                                       if ( allReady( dependencies ) ) {
+                                               // Run ready immediately
+                                               deferred.resolve( mw.loader.require );
+                                       } else if ( anyFailed( dependencies ) ) {
+                                               // Execute error immediately if any dependencies have errors
+                                               deferred.reject(
+                                                       new Error( 'One or more dependencies failed to load' ),
+                                                       dependencies
+                                               );
+                                       } else {
+                                               // Not all dependencies are ready, add to the load queue
+                                               enqueue( dependencies, function () {
+                                                       deferred.resolve( mw.loader.require );
+                                               }, deferred.reject );
+                                       }
+
+                                       return deferred.promise();
+                               },
+
+                               /**
+                                * Load an external script or one or more modules.
+                                *
+                                * This method takes a list of unrelated modules. Use cases:
+                                *
+                                * - A web page will be composed of many different widgets. These widgets independently
+                                *   queue their ResourceLoader modules (`OutputPage::addModules()`). If any of them
+                                *   have problems, or are no longer known (e.g. cached HTML), the other modules
+                                *   should still be loaded.
+                                * - This method is used for preloading, which must not throw. Later code that
+                                *   calls #using() will handle the error.
+                                *
+                                * @param {string|Array} modules Either the name of a module, array of modules,
+                                *  or a URL of an external script or style
+                                * @param {string} [type='text/javascript'] MIME type to use if calling with a URL of an
+                                *  external script or style; acceptable values are "text/css" and
+                                *  "text/javascript"; if no type is provided, text/javascript is assumed.
+                                */
+                               load: function ( modules, type ) {
+                                       var filtered, l;
+
+                                       // Allow calling with a url or single dependency as a string
+                                       if ( typeof modules === 'string' ) {
+                                               // "https://example.org/x.js", "http://example.org/x.js", "//example.org/x.js", "/x.js"
+                                               if ( /^(https?:)?\/?\//.test( modules ) ) {
+                                                       if ( type === 'text/css' ) {
+                                                               l = document.createElement( 'link' );
+                                                               l.rel = 'stylesheet';
+                                                               l.href = modules;
+                                                               $( 'head' ).append( l );
+                                                               return;
+                                                       }
+                                                       if ( type === 'text/javascript' || type === undefined ) {
+                                                               addScript( modules );
+                                                               return;
+                                                       }
+                                                       // Unknown type
+                                                       throw new Error( 'invalid type for external url, must be text/css or text/javascript. not ' + type );
+                                               }
+                                               // Called with single module
+                                               modules = [ modules ];
+                                       }
+
+                                       // Filter out top-level modules that are unknown or failed to load before.
+                                       filtered = $.grep( modules, function ( module ) {
+                                               var state = mw.loader.getState( module );
+                                               return state !== 'error' && state !== 'missing';
+                                       } );
+                                       // Resolve remaining list using the known dependency tree.
+                                       // This also filters out modules with unknown dependencies. (T36853)
+                                       filtered = resolveStubbornly( filtered );
+                                       // If all modules are ready, or if any modules have errors, nothing to be done.
+                                       if ( allReady( filtered ) || anyFailed( filtered ) ) {
+                                               return;
+                                       }
+                                       if ( filtered.length === 0 ) {
+                                               return;
+                                       }
+                                       // Some modules are not yet ready, add to module load queue.
+                                       enqueue( filtered, undefined, undefined );
+                               },
+
+                               /**
+                                * Change the state of one or more modules.
+                                *
+                                * @param {string|Object} module Module name or object of module name/state pairs
+                                * @param {string} state State name
+                                */
+                               state: function ( module, state ) {
+                                       var m;
+
+                                       if ( typeof module === 'object' ) {
+                                               for ( m in module ) {
+                                                       mw.loader.state( m, module[ m ] );
+                                               }
+                                               return;
+                                       }
+                                       if ( !hasOwn.call( registry, module ) ) {
+                                               mw.loader.register( module );
+                                       }
+                                       registry[ module ].state = state;
+                                       if ( $.inArray( state, [ 'ready', 'error', 'missing' ] ) !== -1 ) {
+                                               // Make sure pending modules depending on this one get executed if their
+                                               // dependencies are now fulfilled!
+                                               handlePending( module );
+                                       }
+                               },
+
+                               /**
+                                * Get the version of a module.
+                                *
+                                * @param {string} module Name of module
+                                * @return {string|null} The version, or null if the module (or its version) is not
+                                *  in the registry.
+                                */
+                               getVersion: function ( module ) {
+                                       if ( !hasOwn.call( registry, module ) || registry[ module ].version === undefined ) {
+                                               return null;
+                                       }
+                                       return registry[ module ].version;
+                               },
+
+                               /**
+                                * Get the state of a module.
+                                *
+                                * @param {string} module Name of module
+                                * @return {string|null} The state, or null if the module (or its state) is not
+                                *  in the registry.
+                                */
+                               getState: function ( module ) {
+                                       if ( !hasOwn.call( registry, module ) || registry[ module ].state === undefined ) {
+                                               return null;
+                                       }
+                                       return registry[ module ].state;
+                               },
+
+                               /**
+                                * Get the names of all registered modules.
+                                *
+                                * @return {Array}
+                                */
+                               getModuleNames: function () {
+                                       return Object.keys( registry );
+                               },
+
+                               /**
+                                * Get the exported value of a module.
+                                *
+                                * Modules may provide this via their local `module.exports`.
+                                *
+                                * @protected
+                                * @since 1.27
+                                * @param {string} moduleName Module name
+                                * @return {Mixed} Exported value
+                                */
+                               require: function ( moduleName ) {
+                                       var state = mw.loader.getState( moduleName );
+
+                                       // Only ready modules can be required
+                                       if ( state !== 'ready' ) {
+                                               // Module may've forgotten to declare a dependency
+                                               throw new Error( 'Module "' + moduleName + '" is not loaded.' );
+                                       }
+
+                                       return registry[ moduleName ].module.exports;
+                               },
+
+                               /**
+                                * @inheritdoc mw.inspect#runReports
+                                * @method
+                                */
+                               inspect: function () {
+                                       var args = slice.call( arguments );
+                                       mw.loader.using( 'mediawiki.inspect', function () {
+                                               mw.inspect.runReports.apply( mw.inspect, args );
+                                       } );
+                               },
+
+                               /**
+                                * On browsers that implement the localStorage API, the module store serves as a
+                                * smart complement to the browser cache. Unlike the browser cache, the module store
+                                * can slice a concatenated response from ResourceLoader into its constituent
+                                * modules and cache each of them separately, using each module's versioning scheme
+                                * to determine when the cache should be invalidated.
+                                *
+                                * @singleton
+                                * @class mw.loader.store
+                                */
+                               store: {
+                                       // Whether the store is in use on this page.
+                                       enabled: null,
+
+                                       // Modules whose string representation exceeds 100 kB are
+                                       // ineligible for storage. See bug T66721.
+                                       MODULE_SIZE_MAX: 100 * 1000,
+
+                                       // The contents of the store, mapping '[name]@[version]' keys
+                                       // to module implementations.
+                                       items: {},
+
+                                       // Cache hit stats
+                                       stats: { hits: 0, misses: 0, expired: 0, failed: 0 },
+
+                                       /**
+                                        * Construct a JSON-serializable object representing the content of the store.
+                                        *
+                                        * @return {Object} Module store contents.
+                                        */
+                                       toJSON: function () {
+                                               return { items: mw.loader.store.items, vary: mw.loader.store.getVary() };
+                                       },
+
+                                       /**
+                                        * Get the localStorage key for the entire module store. The key references
+                                        * $wgDBname to prevent clashes between wikis which share a common host.
+                                        *
+                                        * @return {string} localStorage item key
+                                        */
+                                       getStoreKey: function () {
+                                               return 'MediaWikiModuleStore:' + mw.config.get( 'wgDBname' );
+                                       },
+
+                                       /**
+                                        * Get a key on which to vary the module cache.
+                                        *
+                                        * @return {string} String of concatenated vary conditions.
+                                        */
+                                       getVary: function () {
+                                               return [
+                                                       mw.config.get( 'skin' ),
+                                                       mw.config.get( 'wgResourceLoaderStorageVersion' ),
+                                                       mw.config.get( 'wgUserLanguage' )
+                                               ].join( ':' );
+                                       },
+
+                                       /**
+                                        * Initialize the store.
+                                        *
+                                        * Retrieves store from localStorage and (if successfully retrieved) decoding
+                                        * the stored JSON value to a plain object.
+                                        *
+                                        * The try / catch block is used for JSON & localStorage feature detection.
+                                        * See the in-line documentation for Modernizr's localStorage feature detection
+                                        * code for a full account of why we need a try / catch:
+                                        * <https://github.com/Modernizr/Modernizr/blob/v2.7.1/modernizr.js#L771-L796>.
+                                        */
+                                       init: function () {
+                                               var raw, data;
+
+                                               if ( mw.loader.store.enabled !== null ) {
+                                                       // Init already ran
+                                                       return;
+                                               }
+
+                                               if (
+                                                       // Disabled because localStorage quotas are tight and (in Firefox's case)
+                                                       // shared by multiple origins.
+                                                       // See T66721, and <https://bugzilla.mozilla.org/show_bug.cgi?id=1064466>.
+                                                       /Firefox|Opera/.test( navigator.userAgent ) ||
+
+                                                       // Disabled by configuration.
+                                                       !mw.config.get( 'wgResourceLoaderStorageEnabled' )
+                                               ) {
+                                                       // Clear any previous store to free up space. (T66721)
+                                                       mw.loader.store.clear();
+                                                       mw.loader.store.enabled = false;
+                                                       return;
+                                               }
+                                               if ( mw.config.get( 'debug' ) ) {
+                                                       // Disable module store in debug mode
+                                                       mw.loader.store.enabled = false;
+                                                       return;
+                                               }
+
+                                               try {
+                                                       raw = localStorage.getItem( mw.loader.store.getStoreKey() );
+                                                       // If we get here, localStorage is available; mark enabled
+                                                       mw.loader.store.enabled = true;
+                                                       data = JSON.parse( raw );
+                                                       if ( data && typeof data.items === 'object' && data.vary === mw.loader.store.getVary() ) {
+                                                               mw.loader.store.items = data.items;
+                                                               return;
+                                                       }
+                                               } catch ( e ) {
+                                                       mw.track( 'resourceloader.exception', { exception: e, source: 'store-localstorage-init' } );
+                                               }
+
+                                               if ( raw === undefined ) {
+                                                       // localStorage failed; disable store
+                                                       mw.loader.store.enabled = false;
+                                               } else {
+                                                       mw.loader.store.update();
+                                               }
+                                       },
+
+                                       /**
+                                        * Retrieve a module from the store and update cache hit stats.
+                                        *
+                                        * @param {string} module Module name
+                                        * @return {string|boolean} Module implementation or false if unavailable
+                                        */
+                                       get: function ( module ) {
+                                               var key;
+
+                                               if ( !mw.loader.store.enabled ) {
+                                                       return false;
+                                               }
+
+                                               key = getModuleKey( module );
+                                               if ( key in mw.loader.store.items ) {
+                                                       mw.loader.store.stats.hits++;
+                                                       return mw.loader.store.items[ key ];
+                                               }
+                                               mw.loader.store.stats.misses++;
+                                               return false;
+                                       },
+
+                                       /**
+                                        * Stringify a module and queue it for storage.
+                                        *
+                                        * @param {string} module Module name
+                                        * @param {Object} descriptor The module's descriptor as set in the registry
+                                        * @return {boolean} Module was set
+                                        */
+                                       set: function ( module, descriptor ) {
+                                               var args, key, src;
+
+                                               if ( !mw.loader.store.enabled ) {
+                                                       return false;
+                                               }
+
+                                               key = getModuleKey( module );
+
+                                               if (
+                                                       // Already stored a copy of this exact version
+                                                       key in mw.loader.store.items ||
+                                                       // Module failed to load
+                                                       descriptor.state !== 'ready' ||
+                                                       // Unversioned, private, or site-/user-specific
+                                                       ( !descriptor.version || $.inArray( descriptor.group, [ 'private', 'user' ] ) !== -1 ) ||
+                                                       // Partial descriptor
+                                                       // (e.g. skipped module, or style module with state=ready)
+                                                       $.inArray( undefined, [ descriptor.script, descriptor.style,
+                                                               descriptor.messages, descriptor.templates ] ) !== -1
+                                               ) {
+                                                       // Decline to store
+                                                       return false;
+                                               }
+
+                                               try {
+                                                       args = [
+                                                               JSON.stringify( key ),
+                                                               typeof descriptor.script === 'function' ?
+                                                                       String( descriptor.script ) :
+                                                                       JSON.stringify( descriptor.script ),
+                                                               JSON.stringify( descriptor.style ),
+                                                               JSON.stringify( descriptor.messages ),
+                                                               JSON.stringify( descriptor.templates )
+                                                       ];
+                                                       // Attempted workaround for a possible Opera bug (bug T59567).
+                                                       // This regex should never match under sane conditions.
+                                                       if ( /^\s*\(/.test( args[ 1 ] ) ) {
+                                                               args[ 1 ] = 'function' + args[ 1 ];
+                                                               mw.track( 'resourceloader.assert', { source: 'bug-T59567' } );
+                                                       }
+                                               } catch ( e ) {
+                                                       mw.track( 'resourceloader.exception', { exception: e, source: 'store-localstorage-json' } );
+                                                       return false;
+                                               }
+
+                                               src = 'mw.loader.implement(' + args.join( ',' ) + ');';
+                                               if ( src.length > mw.loader.store.MODULE_SIZE_MAX ) {
+                                                       return false;
+                                               }
+                                               mw.loader.store.items[ key ] = src;
+                                               mw.loader.store.update();
+                                               return true;
+                                       },
+
+                                       /**
+                                        * Iterate through the module store, removing any item that does not correspond
+                                        * (in name and version) to an item in the module registry.
+                                        *
+                                        * @return {boolean} Store was pruned
+                                        */
+                                       prune: function () {
+                                               var key, module;
+
+                                               if ( !mw.loader.store.enabled ) {
+                                                       return false;
+                                               }
+
+                                               for ( key in mw.loader.store.items ) {
+                                                       module = key.slice( 0, key.indexOf( '@' ) );
+                                                       if ( getModuleKey( module ) !== key ) {
+                                                               mw.loader.store.stats.expired++;
+                                                               delete mw.loader.store.items[ key ];
+                                                       } else if ( mw.loader.store.items[ key ].length > mw.loader.store.MODULE_SIZE_MAX ) {
+                                                               // This value predates the enforcement of a size limit on cached modules.
+                                                               delete mw.loader.store.items[ key ];
+                                                       }
+                                               }
+                                               return true;
+                                       },
+
+                                       /**
+                                        * Clear the entire module store right now.
+                                        */
+                                       clear: function () {
+                                               mw.loader.store.items = {};
+                                               try {
+                                                       localStorage.removeItem( mw.loader.store.getStoreKey() );
+                                               } catch ( ignored ) {}
+                                       },
+
+                                       /**
+                                        * Sync in-memory store back to localStorage.
+                                        *
+                                        * This function debounces updates. When called with a flush already pending,
+                                        * the call is coalesced into the pending update. The call to
+                                        * localStorage.setItem will be naturally deferred until the page is quiescent.
+                                        *
+                                        * Because localStorage is shared by all pages from the same origin, if multiple
+                                        * pages are loaded with different module sets, the possibility exists that
+                                        * modules saved by one page will be clobbered by another. But the impact would
+                                        * be minor and the problem would be corrected by subsequent page views.
+                                        *
+                                        * @method
+                                        */
+                                       update: ( function () {
+                                               var hasPendingWrite = false;
+
+                                               function flushWrites() {
+                                                       var data, key;
+                                                       if ( !hasPendingWrite || !mw.loader.store.enabled ) {
+                                                               return;
+                                                       }
+
+                                                       mw.loader.store.prune();
+                                                       key = mw.loader.store.getStoreKey();
+                                                       try {
+                                                               // Replacing the content of the module store might fail if the new
+                                                               // contents would exceed the browser's localStorage size limit. To
+                                                               // avoid clogging the browser with stale data, always remove the old
+                                                               // value before attempting to set the new one.
+                                                               localStorage.removeItem( key );
+                                                               data = JSON.stringify( mw.loader.store );
+                                                               localStorage.setItem( key, data );
+                                                       } catch ( e ) {
+                                                               mw.track( 'resourceloader.exception', { exception: e, source: 'store-localstorage-update' } );
+                                                       }
+
+                                                       hasPendingWrite = false;
+                                               }
+
+                                               return function () {
+                                                       if ( !hasPendingWrite ) {
+                                                               hasPendingWrite = true;
+                                                               mw.requestIdleCallback( flushWrites );
+                                                       }
+                                               };
+                                       }() )
+                               }
+                       };
+               }() ),
+
+               /**
+                * HTML construction helper functions
+                *
+                *     @example
+                *
+                *     var Html, output;
+                *
+                *     Html = mw.html;
+                *     output = Html.element( 'div', {}, new Html.Raw(
+                *         Html.element( 'img', { src: '<' } )
+                *     ) );
+                *     mw.log( output ); // <div><img src="&lt;"/></div>
+                *
+                * @class mw.html
+                * @singleton
+                */
+               html: ( function () {
+                       function escapeCallback( s ) {
+                               switch ( s ) {
+                                       case '\'':
+                                               return '&#039;';
+                                       case '"':
+                                               return '&quot;';
+                                       case '<':
+                                               return '&lt;';
+                                       case '>':
+                                               return '&gt;';
+                                       case '&':
+                                               return '&amp;';
+                               }
+                       }
+
+                       return {
+                               /**
+                                * Escape a string for HTML.
+                                *
+                                * Converts special characters to HTML entities.
+                                *
+                                *     mw.html.escape( '< > \' & "' );
+                                *     // Returns &lt; &gt; &#039; &amp; &quot;
+                                *
+                                * @param {string} s The string to escape
+                                * @return {string} HTML
+                                */
+                               escape: function ( s ) {
+                                       return s.replace( /['"<>&]/g, escapeCallback );
+                               },
+
+                               /**
+                                * Create an HTML element string, with safe escaping.
+                                *
+                                * @param {string} name The tag name.
+                                * @param {Object} [attrs] An object with members mapping element names to values
+                                * @param {string|mw.html.Raw|mw.html.Cdata|null} [contents=null] The contents of the element.
+                                *
+                                *  - string: Text to be escaped.
+                                *  - null: The element is treated as void with short closing form, e.g. `<br/>`.
+                                *  - this.Raw: The raw value is directly included.
+                                *  - this.Cdata: The raw value is directly included. An exception is
+                                *    thrown if it contains any illegal ETAGO delimiter.
+                                *    See <https://www.w3.org/TR/html401/appendix/notes.html#h-B.3.2>.
+                                * @return {string} HTML
+                                */
+                               element: function ( name, attrs, contents ) {
+                                       var v, attrName, s = '<' + name;
+
+                                       if ( attrs ) {
+                                               for ( attrName in attrs ) {
+                                                       v = attrs[ attrName ];
+                                                       // Convert name=true, to name=name
+                                                       if ( v === true ) {
+                                                               v = attrName;
+                                                       // Skip name=false
+                                                       } else if ( v === false ) {
+                                                               continue;
+                                                       }
+                                                       s += ' ' + attrName + '="' + this.escape( String( v ) ) + '"';
+                                               }
+                                       }
+                                       if ( contents === undefined || contents === null ) {
+                                               // Self close tag
+                                               s += '/>';
+                                               return s;
+                                       }
+                                       // Regular open tag
+                                       s += '>';
+                                       switch ( typeof contents ) {
+                                               case 'string':
+                                                       // Escaped
+                                                       s += this.escape( contents );
+                                                       break;
+                                               case 'number':
+                                               case 'boolean':
+                                                       // Convert to string
+                                                       s += String( contents );
+                                                       break;
+                                               default:
+                                                       if ( contents instanceof this.Raw ) {
+                                                               // Raw HTML inclusion
+                                                               s += contents.value;
+                                                       } else if ( contents instanceof this.Cdata ) {
+                                                               // CDATA
+                                                               if ( /<\/[a-zA-z]/.test( contents.value ) ) {
+                                                                       throw new Error( 'mw.html.element: Illegal end tag found in CDATA' );
+                                                               }
+                                                               s += contents.value;
+                                                       } else {
+                                                               throw new Error( 'mw.html.element: Invalid type of contents' );
+                                                       }
+                                       }
+                                       s += '</' + name + '>';
+                                       return s;
+                               },
+
+                               /**
+                                * Wrapper object for raw HTML passed to mw.html.element().
+                                *
+                                * @class mw.html.Raw
+                                * @constructor
+                                * @param {string} value
+                                */
+                               Raw: function ( value ) {
+                                       this.value = value;
+                               },
+
+                               /**
+                                * Wrapper object for CDATA element contents passed to mw.html.element()
+                                *
+                                * @class mw.html.Cdata
+                                * @constructor
+                                * @param {string} value
+                                */
+                               Cdata: function ( value ) {
+                                       this.value = value;
+                               }
+                       };
+               }() ),
+
+               // Skeleton user object, extended by the 'mediawiki.user' module.
+               /**
+                * @class mw.user
+                * @singleton
+                */
+               user: {
+                       /**
+                        * @property {mw.Map}
+                        */
+                       options: new Map(),
+                       /**
+                        * @property {mw.Map}
+                        */
+                       tokens: new Map()
+               },
+
+               // OOUI widgets specific to MediaWiki
+               widgets: {},
+
+               /**
+                * Registry and firing of events.
+                *
+                * MediaWiki has various interface components that are extended, enhanced
+                * or manipulated in some other way by extensions, gadgets and even
+                * in core itself.
+                *
+                * This framework helps streamlining the timing of when these other
+                * code paths fire their plugins (instead of using document-ready,
+                * which can and should be limited to firing only once).
+                *
+                * Features like navigating to other wiki pages, previewing an edit
+                * and editing itself – without a refresh – can then retrigger these
+                * hooks accordingly to ensure everything still works as expected.
+                *
+                * Example usage:
+                *
+                *     mw.hook( 'wikipage.content' ).add( fn ).remove( fn );
+                *     mw.hook( 'wikipage.content' ).fire( $content );
+                *
+                * Handlers can be added and fired for arbitrary event names at any time. The same
+                * event can be fired multiple times. The last run of an event is memorized
+                * (similar to `$(document).ready` and `$.Deferred().done`).
+                * This means if an event is fired, and a handler added afterwards, the added
+                * function will be fired right away with the last given event data.
+                *
+                * Like Deferreds and Promises, the mw.hook object is both detachable and chainable.
+                * Thus allowing flexible use and optimal maintainability and authority control.
+                * You can pass around the `add` and/or `fire` method to another piece of code
+                * without it having to know the event name (or `mw.hook` for that matter).
+                *
+                *     var h = mw.hook( 'bar.ready' );
+                *     new mw.Foo( .. ).fetch( { callback: h.fire } );
+                *
+                * Note: Events are documented with an underscore instead of a dot in the event
+                * name due to jsduck not supporting dots in that position.
+                *
+                * @class mw.hook
+                */
+               hook: ( function () {
+                       var lists = {};
+
+                       /**
+                        * Create an instance of mw.hook.
+                        *
+                        * @method hook
+                        * @member mw
+                        * @param {string} name Name of hook.
+                        * @return {mw.hook}
+                        */
+                       return function ( name ) {
+                               var list = hasOwn.call( lists, name ) ?
+                                       lists[ name ] :
+                                       lists[ name ] = $.Callbacks( 'memory' );
+
+                               return {
+                                       /**
+                                        * Register a hook handler
+                                        *
+                                        * @param {...Function} handler Function to bind.
+                                        * @chainable
+                                        */
+                                       add: list.add,
+
+                                       /**
+                                        * Unregister a hook handler
+                                        *
+                                        * @param {...Function} handler Function to unbind.
+                                        * @chainable
+                                        */
+                                       remove: list.remove,
+
+                                       // eslint-disable-next-line valid-jsdoc
+                                       /**
+                                        * Run a hook.
+                                        *
+                                        * @param {...Mixed} data
+                                        * @chainable
+                                        */
+                                       fire: function () {
+                                               return list.fireWith.call( this, null, slice.call( arguments ) );
+                                       }
+                               };
+                       };
+               }() )
+       };
+
+       // Alias $j to jQuery for backwards compatibility
+       // @deprecated since 1.23 Use $ or jQuery instead
+       mw.log.deprecate( window, '$j', $, 'Use $ or jQuery instead.' );
+
+       /**
+        * Log a message to window.console, if possible.
+        *
+        * Useful to force logging of some errors that are otherwise hard to detect (i.e., this logs
+        * also in production mode). Gets console references in each invocation instead of caching the
+        * reference, so that debugging tools loaded later are supported (e.g. Firebug Lite in IE).
+        *
+        * @private
+        * @param {string} topic Stream name passed by mw.track
+        * @param {Object} data Data passed by mw.track
+        * @param {Error} [data.exception]
+        * @param {string} data.source Error source
+        * @param {string} [data.module] Name of module which caused the error
+        */
+       function logError( topic, data ) {
+               /* eslint-disable no-console */
+               var msg,
+                       e = data.exception,
+                       source = data.source,
+                       module = data.module,
+                       console = window.console;
+
+               if ( console && console.log ) {
+                       msg = ( e ? 'Exception' : 'Error' ) + ' in ' + source;
+                       if ( module ) {
+                               msg += ' in module ' + module;
+                       }
+                       msg += ( e ? ':' : '.' );
+                       console.log( msg );
+
+                       // If we have an exception object, log it to the warning channel to trigger
+                       // proper stacktraces in browsers that support it.
+                       if ( e && console.warn ) {
+                               console.warn( String( e ), e );
+                       }
+               }
+               /* eslint-enable no-console */
+       }
+
+       // Subscribe to error streams
+       mw.trackSubscribe( 'resourceloader.exception', logError );
+       mw.trackSubscribe( 'resourceloader.assert', logError );
+
+       /**
+        * Fired when all modules associated with the page have finished loading.
+        *
+        * @event resourceloader_loadEnd
+        * @member mw.hook
+        */
+       $( function () {
+               var loading, modules;
+
+               modules = $.grep( mw.loader.getModuleNames(), function ( module ) {
+                       return mw.loader.getState( module ) === 'loading';
+               } );
+               // We only need a callback, not any actual module. First try a single using()
+               // for all loading modules. If one fails, fall back to tracking each module
+               // separately via $.when(), this is expensive.
+               loading = mw.loader.using( modules ).then( null, function () {
+                       var all = modules.map( function ( module ) {
+                               return mw.loader.using( module ).then( null, function () {
+                                       return $.Deferred().resolve();
+                               } );
+                       } );
+                       return $.when.apply( $, all );
+               } );
+               loading.then( function () {
+                       /* global mwPerformance */
+                       mwPerformance.mark( 'mwLoadEnd' );
+                       mw.hook( 'resourceloader.loadEnd' ).fire();
+               } );
+       } );
+
+       // Attach to window and globally alias
+       window.mw = window.mediaWiki = mw;
+}( jQuery ) );