resources/src/mediawiki/mediawiki.js

   1 /**
   2  * Base library for MediaWiki.
   3  *
   4  * Exposed globally as `mediaWiki` with `mw` as shortcut.
   5  *
   6  * @class mw
   7  * @alternateClassName mediaWiki
   8  * @singleton
   9  */
  10 /*jshint latedef:false */
  11 /*global sha1 */
  12 ( function ( $ ) {
  13         'use strict';
  14
  15         var mw,
  16                 hasOwn = Object.prototype.hasOwnProperty,
  17                 slice = Array.prototype.slice,
  18                 trackCallbacks = $.Callbacks( 'memory' ),
  19                 trackHandlers = [],
  20                 trackQueue = [];
  21
  22         /**
  23          * Create an object that can be read from or written to from methods that allow
  24          * interaction both with single and multiple properties at once.
  25          *
  26          *     @example
  27          *
  28          *     var collection, query, results;
  29          *
  30          *     // Create your address book
  31          *     collection = new mw.Map();
  32          *
  33          *     // This data could be coming from an external source (eg. API/AJAX)
  34          *     collection.set( {
  35          *         'John Doe': 'john@example.org',
  36          *         'Jane Doe': 'jane@example.org',
  37          *         'George van Halen': 'gvanhalen@example.org'
  38          *     } );
  39          *
  40          *     wanted = ['John Doe', 'Jane Doe', 'Daniel Jackson'];
  41          *
  42          *     // You can detect missing keys first
  43          *     if ( !collection.exists( wanted ) ) {
  44          *         // One or more are missing (in this case: "Daniel Jackson")
  45          *         mw.log( 'One or more names were not found in your address book' );
  46          *     }
  47          *
  48          *     // Or just let it give you what it can. Optionally fill in from a default.
  49          *     results = collection.get( wanted, 'nobody@example.com' );
  50          *     mw.log( results['Jane Doe'] ); // "jane@example.org"
  51          *     mw.log( results['Daniel Jackson'] ); // "nobody@example.com"
  52          *
  53          * @class mw.Map
  54          *
  55          * @constructor
  56          * @param {Object|boolean} [values] The value-baring object to be mapped. Defaults to an
  57          *  empty object.
  58          *  For backwards-compatibility with mw.config, this can also be `true` in which case values
  59          *  are copied to the Window object as global variables (T72470). Values are copied in
  60          *  one direction only. Changes to globals are not reflected in the map.
  61          */
  62         function Map( values ) {
  63                 if ( values === true ) {
  64                         this.values = {};
  65
  66                         // Override #set to also set the global variable
  67                         this.set = function ( selection, value ) {
  68                                 var s;
  69
  70                                 if ( $.isPlainObject( selection ) ) {
  71                                         for ( s in selection ) {
  72                                                 setGlobalMapValue( this, s, selection[ s ] );
  73                                         }
  74                                         return true;
  75                                 }
  76                                 if ( typeof selection === 'string' && arguments.length ) {
  77                                         setGlobalMapValue( this, selection, value );
  78                                         return true;
  79                                 }
  80                                 return false;
  81                         };
  82
  83                         return;
  84                 }
  85
  86                 this.values = values || {};
  87         }
  88
  89         /**
  90          * Alias property to the global object.
  91          *
  92          * @private
  93          * @static
  94          * @param {mw.Map} map
  95          * @param {string} key
  96          * @param {Mixed} value
  97          */
  98         function setGlobalMapValue( map, key, value ) {
  99                 map.values[ key ] = value;
 100                 mw.log.deprecate(
 101                                 window,
 102                                 key,
 103                                 value,
 104                                 // Deprecation notice for mw.config globals (T58550, T72470)
 105                                 map === mw.config && 'Use mw.config instead.'
 106                 );
 107         }
 108
 109         Map.prototype = {
 110                 /**
 111                  * Get the value of one or more keys.
 112                  *
 113                  * If called with no arguments, all values are returned.
 114                  *
 115                  * @param {string|Array} [selection] Key or array of keys to retrieve values for.
 116                  * @param {Mixed} [fallback=null] Value for keys that don't exist.
 117                  * @return {Mixed|Object| null} If selection was a string, returns the value,
 118                  *  If selection was an array, returns an object of key/values.
 119                  *  If no selection is passed, the 'values' container is returned. (Beware that,
 120                  *  as is the default in JavaScript, the object is returned by reference.)
 121                  */
 122                 get: function ( selection, fallback ) {
 123                         var results, i;
 124                         // If we only do this in the `return` block, it'll fail for the
 125                         // call to get() from the mutli-selection block.
 126                         fallback = arguments.length > 1 ? fallback : null;
 127
 128                         if ( $.isArray( selection ) ) {
 129                                 selection = slice.call( selection );
 130                                 results = {};
 131                                 for ( i = 0; i < selection.length; i++ ) {
 132                                         results[ selection[ i ] ] = this.get( selection[ i ], fallback );
 133                                 }
 134                                 return results;
 135                         }
 136
 137                         if ( typeof selection === 'string' ) {
 138                                 if ( !hasOwn.call( this.values, selection ) ) {
 139                                         return fallback;
 140                                 }
 141                                 return this.values[ selection ];
 142                         }
 143
 144                         if ( selection === undefined ) {
 145                                 return this.values;
 146                         }
 147
 148                         // Invalid selection key
 149                         return null;
 150                 },
 151
 152                 /**
 153                  * Set one or more key/value pairs.
 154                  *
 155                  * @param {string|Object} selection Key to set value for, or object mapping keys to values
 156                  * @param {Mixed} [value] Value to set (optional, only in use when key is a string)
 157                  * @return {boolean} True on success, false on failure
 158                  */
 159                 set: function ( selection, value ) {
 160                         var s;
 161
 162                         if ( $.isPlainObject( selection ) ) {
 163                                 for ( s in selection ) {
 164                                         this.values[ s ] = selection[ s ];
 165                                 }
 166                                 return true;
 167                         }
 168                         if ( typeof selection === 'string' && arguments.length > 1 ) {
 169                                 this.values[ selection ] = value;
 170                                 return true;
 171                         }
 172                         return false;
 173                 },
 174
 175                 /**
 176                  * Check if one or more keys exist.
 177                  *
 178                  * @param {Mixed} selection Key or array of keys to check
 179                  * @return {boolean} True if the key(s) exist
 180                  */
 181                 exists: function ( selection ) {
 182                         var s;
 183
 184                         if ( $.isArray( selection ) ) {
 185                                 for ( s = 0; s < selection.length; s++ ) {
 186                                         if ( typeof selection[ s ] !== 'string' || !hasOwn.call( this.values, selection[ s ] ) ) {
 187                                                 return false;
 188                                         }
 189                                 }
 190                                 return true;
 191                         }
 192                         return typeof selection === 'string' && hasOwn.call( this.values, selection );
 193                 }
 194         };
 195
 196         /**
 197          * Object constructor for messages.
 198          *
 199          * Similar to the Message class in MediaWiki PHP.
 200          *
 201          * Format defaults to 'text'.
 202          *
 203          *     @example
 204          *
 205          *     var obj, str;
 206          *     mw.messages.set( {
 207          *         'hello': 'Hello world',
 208          *         'hello-user': 'Hello, $1!',
 209          *         'welcome-user': 'Welcome back to $2, $1! Last visit by $1: $3'
 210          *     } );
 211          *
 212          *     obj = new mw.Message( mw.messages, 'hello' );
 213          *     mw.log( obj.text() );
 214          *     // Hello world
 215          *
 216          *     obj = new mw.Message( mw.messages, 'hello-user', [ 'John Doe' ] );
 217          *     mw.log( obj.text() );
 218          *     // Hello, John Doe!
 219          *
 220          *     obj = new mw.Message( mw.messages, 'welcome-user', [ 'John Doe', 'Wikipedia', '2 hours ago' ] );
 221          *     mw.log( obj.text() );
 222          *     // Welcome back to Wikipedia, John Doe! Last visit by John Doe: 2 hours ago
 223          *
 224          *     // Using mw.message shortcut
 225          *     obj = mw.message( 'hello-user', 'John Doe' );
 226          *     mw.log( obj.text() );
 227          *     // Hello, John Doe!
 228          *
 229          *     // Using mw.msg shortcut
 230          *     str = mw.msg( 'hello-user', 'John Doe' );
 231          *     mw.log( str );
 232          *     // Hello, John Doe!
 233          *
 234          *     // Different formats
 235          *     obj = new mw.Message( mw.messages, 'hello-user', [ 'John "Wiki" <3 Doe' ] );
 236          *
 237          *     obj.format = 'text';
 238          *     str = obj.toString();
 239          *     // Same as:
 240          *     str = obj.text();
 241          *
 242          *     mw.log( str );
 243          *     // Hello, John "Wiki" <3 Doe!
 244          *
 245          *     mw.log( obj.escaped() );
 246          *     // Hello, John &quot;Wiki&quot; &lt;3 Doe!
 247          *
 248          * @class mw.Message
 249          *
 250          * @constructor
 251          * @param {mw.Map} map Message store
 252          * @param {string} key
 253          * @param {Array} [parameters]
 254          */
 255         function Message( map, key, parameters ) {
 256                 this.format = 'text';
 257                 this.map = map;
 258                 this.key = key;
 259                 this.parameters = parameters === undefined ? [] : slice.call( parameters );
 260                 return this;
 261         }
 262
 263         Message.prototype = {
 264                 /**
 265                  * Get parsed contents of the message.
 266                  *
 267                  * The default parser does simple $N replacements and nothing else.
 268                  * This may be overridden to provide a more complex message parser.
 269                  * The primary override is in the mediawiki.jqueryMsg module.
 270                  *
 271                  * This function will not be called for nonexistent messages.
 272                  *
 273                  * @return {string} Parsed message
 274                  */
 275                 parser: function () {
 276                         return mw.format.apply( null, [ this.map.get( this.key ) ].concat( this.parameters ) );
 277                 },
 278
 279                 /**
 280                  * Add (does not replace) parameters for `N$` placeholder values.
 281                  *
 282                  * @param {Array} parameters
 283                  * @chainable
 284                  */
 285                 params: function ( parameters ) {
 286                         var i;
 287                         for ( i = 0; i < parameters.length; i++ ) {
 288                                 this.parameters.push( parameters[ i ] );
 289                         }
 290                         return this;
 291                 },
 292
 293                 /**
 294                  * Convert message object to its string form based on current format.
 295                  *
 296                  * @return {string} Message as a string in the current form, or `<key>` if key
 297                  *  does not exist.
 298                  */
 299                 toString: function () {
 300                         var text;
 301
 302                         if ( !this.exists() ) {
 303                                 // Use <key> as text if key does not exist
 304                                 if ( this.format === 'escaped' || this.format === 'parse' ) {
 305                                         // format 'escaped' and 'parse' need to have the brackets and key html escaped
 306                                         return mw.html.escape( '<' + this.key + '>' );
 307                                 }
 308                                 return '<' + this.key + '>';
 309                         }
 310
 311                         if ( this.format === 'plain' || this.format === 'text' || this.format === 'parse' ) {
 312                                 text = this.parser();
 313                         }
 314
 315                         if ( this.format === 'escaped' ) {
 316                                 text = this.parser();
 317                                 text = mw.html.escape( text );
 318                         }
 319
 320                         return text;
 321                 },
 322
 323                 /**
 324                  * Change format to 'parse' and convert message to string
 325                  *
 326                  * If jqueryMsg is loaded, this parses the message text from wikitext
 327                  * (where supported) to HTML
 328                  *
 329                  * Otherwise, it is equivalent to plain.
 330                  *
 331                  * @return {string} String form of parsed message
 332                  */
 333                 parse: function () {
 334                         this.format = 'parse';
 335                         return this.toString();
 336                 },
 337
 338                 /**
 339                  * Change format to 'plain' and convert message to string
 340                  *
 341                  * This substitutes parameters, but otherwise does not change the
 342                  * message text.
 343                  *
 344                  * @return {string} String form of plain message
 345                  */
 346                 plain: function () {
 347                         this.format = 'plain';
 348                         return this.toString();
 349                 },
 350
 351                 /**
 352                  * Change format to 'text' and convert message to string
 353                  *
 354                  * If jqueryMsg is loaded, {{-transformation is done where supported
 355                  * (such as {{plural:}}, {{gender:}}, {{int:}}).
 356                  *
 357                  * Otherwise, it is equivalent to plain
 358                  *
 359                  * @return {string} String form of text message
 360                  */
 361                 text: function () {
 362                         this.format = 'text';
 363                         return this.toString();
 364                 },
 365
 366                 /**
 367                  * Change the format to 'escaped' and convert message to string
 368                  *
 369                  * This is equivalent to using the 'text' format (see #text), then
 370                  * HTML-escaping the output.
 371                  *
 372                  * @return {string} String form of html escaped message
 373                  */
 374                 escaped: function () {
 375                         this.format = 'escaped';
 376                         return this.toString();
 377                 },
 378
 379                 /**
 380                  * Check if a message exists
 381                  *
 382                  * @see mw.Map#exists
 383                  * @return {boolean}
 384                  */
 385                 exists: function () {
 386                         return this.map.exists( this.key );
 387                 }
 388         };
 389
 390         /**
 391          * @class mw
 392          */
 393         mw = {
 394
 395                 /**
 396                  * Get the current time, measured in milliseconds since January 1, 1970 (UTC).
 397                  *
 398                  * On browsers that implement the Navigation Timing API, this function will produce floating-point
 399                  * values with microsecond precision that are guaranteed to be monotonic. On all other browsers,
 400                  * it will fall back to using `Date`.
 401                  *
 402                  * @return {number} Current time
 403                  */
 404                 now: ( function () {
 405                         var perf = window.performance,
 406                                 navStart = perf && perf.timing && perf.timing.navigationStart;
 407                         return navStart && typeof perf.now === 'function' ?
 408                                 function () { return navStart + perf.now(); } :
 409                                 function () { return +new Date(); };
 410                 }() ),
 411
 412                 /**
 413                  * Format a string. Replace $1, $2 ... $N with positional arguments.
 414                  *
 415                  * Used by Message#parser().
 416                  *
 417                  * @since 1.25
 418                  * @param {string} formatString Format string
 419                  * @param {...Mixed} parameters Values for $N replacements
 420                  * @return {string} Formatted string
 421                  */
 422                 format: function ( formatString ) {
 423                         var parameters = slice.call( arguments, 1 );
 424                         return formatString.replace( /\$(\d+)/g, function ( str, match ) {
 425                                 var index = parseInt( match, 10 ) - 1;
 426                                 return parameters[ index ] !== undefined ? parameters[ index ] : '$' + match;
 427                         } );
 428                 },
 429
 430                 /**
 431                  * Track an analytic event.
 432                  *
 433                  * This method provides a generic means for MediaWiki JavaScript code to capture state
 434                  * information for analysis. Each logged event specifies a string topic name that describes
 435                  * the kind of event that it is. Topic names consist of dot-separated path components,
 436                  * arranged from most general to most specific. Each path component should have a clear and
 437                  * well-defined purpose.
 438                  *
 439                  * Data handlers are registered via `mw.trackSubscribe`, and receive the full set of
 440                  * events that match their subcription, including those that fired before the handler was
 441                  * bound.
 442                  *
 443                  * @param {string} topic Topic name
 444                  * @param {Object} [data] Data describing the event, encoded as an object
 445                  */
 446                 track: function ( topic, data ) {
 447                         trackQueue.push( { topic: topic, timeStamp: mw.now(), data: data } );
 448                         trackCallbacks.fire( trackQueue );
 449                 },
 450
 451                 /**
 452                  * Register a handler for subset of analytic events, specified by topic.
 453                  *
 454                  * Handlers will be called once for each tracked event, including any events that fired before the
 455                  * handler was registered; 'this' is set to a plain object with a 'timeStamp' property indicating
 456                  * the exact time at which the event fired, a string 'topic' property naming the event, and a
 457                  * 'data' property which is an object of event-specific data. The event topic and event data are
 458                  * also passed to the callback as the first and second arguments, respectively.
 459                  *
 460                  * @param {string} topic Handle events whose name starts with this string prefix
 461                  * @param {Function} callback Handler to call for each matching tracked event
 462                  * @param {string} callback.topic
 463                  * @param {Object} [callback.data]
 464                  */
 465                 trackSubscribe: function ( topic, callback ) {
 466                         var seen = 0;
 467                         function handler( trackQueue ) {
 468                                 var event;
 469                                 for ( ; seen < trackQueue.length; seen++ ) {
 470                                         event = trackQueue[ seen ];
 471                                         if ( event.topic.indexOf( topic ) === 0 ) {
 472                                                 callback.call( event, event.topic, event.data );
 473                                         }
 474                                 }
 475                         }
 476
 477                         trackHandlers.push( [ handler, callback ] );
 478
 479                         trackCallbacks.add( handler );
 480                 },
 481
 482                 /**
 483                  * Stop handling events for a particular handler
 484                  *
 485                  * @param {Function} callback
 486                  */
 487                 trackUnsubscribe: function ( callback ) {
 488                         trackHandlers = $.grep( trackHandlers, function ( fns ) {
 489                                 if ( fns[ 1 ] === callback ) {
 490                                         trackCallbacks.remove( fns[ 0 ] );
 491                                         // Ensure the tuple is removed to avoid holding on to closures
 492                                         return false;
 493                                 }
 494                                 return true;
 495                         } );
 496                 },
 497
 498                 // Expose Map constructor
 499                 Map: Map,
 500
 501                 // Expose Message constructor
 502                 Message: Message,
 503
 504                 /**
 505                  * Map of configuration values.
 506                  *
 507                  * Check out [the complete list of configuration values](https://www.mediawiki.org/wiki/Manual:Interface/JavaScript#mw.config)
 508                  * on mediawiki.org.
 509                  *
 510                  * If `$wgLegacyJavaScriptGlobals` is true, this Map will add its values to the
 511                  * global `window` object.
 512                  *
 513                  * @property {mw.Map} config
 514                  */
 515                 // Dummy placeholder later assigned in ResourceLoaderStartUpModule
 516                 config: null,
 517
 518                 /**
 519                  * Empty object for third-party libraries, for cases where you don't
 520                  * want to add a new global, or the global is bad and needs containment
 521                  * or wrapping.
 522                  *
 523                  * @property
 524                  */
 525                 libs: {},
 526
 527                 /**
 528                  * Access container for deprecated functionality that can be moved from
 529                  * from their legacy location and attached to this object (e.g. a global
 530                  * function that is deprecated and as stop-gap can be exposed through here).
 531                  *
 532                  * This was reserved for future use but never ended up being used.
 533                  *
 534                  * @deprecated since 1.22 Let deprecated identifiers keep their original name
 535                  *  and use mw.log#deprecate to create an access container for tracking.
 536                  * @property
 537                  */
 538                 legacy: {},
 539
 540                 /**
 541                  * Store for messages.
 542                  *
 543                  * @property {mw.Map}
 544                  */
 545                 messages: new Map(),
 546
 547                 /**
 548                  * Store for templates associated with a module.
 549                  *
 550                  * @property {mw.Map}
 551                  */
 552                 templates: new Map(),
 553
 554                 /**
 555                  * Get a message object.
 556                  *
 557                  * Shortcut for `new mw.Message( mw.messages, key, parameters )`.
 558                  *
 559                  * @see mw.Message
 560                  * @param {string} key Key of message to get
 561                  * @param {...Mixed} parameters Values for $N replacements
 562                  * @return {mw.Message}
 563                  */
 564                 message: function ( key ) {
 565                         var parameters = slice.call( arguments, 1 );
 566                         return new Message( mw.messages, key, parameters );
 567                 },
 568
 569                 /**
 570                  * Get a message string using the (default) 'text' format.
 571                  *
 572                  * Shortcut for `mw.message( key, parameters... ).text()`.
 573                  *
 574                  * @see mw.Message
 575                  * @param {string} key Key of message to get
 576                  * @param {...Mixed} parameters Values for $N replacements
 577                  * @return {string}
 578                  */
 579                 msg: function () {
 580                         return mw.message.apply( mw.message, arguments ).toString();
 581                 },
 582
 583                 /**
 584                  * Dummy placeholder for {@link mw.log}
 585                  *
 586                  * @method
 587                  */
 588                 log: ( function () {
 589                         // Also update the restoration of methods in mediawiki.log.js
 590                         // when adding or removing methods here.
 591                         var log = function () {},
 592                                 console = window.console;
 593
 594                         /**
 595                          * @class mw.log
 596                          * @singleton
 597                          */
 598
 599                         /**
 600                          * Write a message to the console's warning channel.
 601                          * Actions not supported by the browser console are silently ignored.
 602                          *
 603                          * @param {...string} msg Messages to output to console
 604                          */
 605                         log.warn = console && console.warn && Function.prototype.bind ?
 606                                 Function.prototype.bind.call( console.warn, console ) :
 607                                 $.noop;
 608
 609                         /**
 610                          * Write a message to the console's error channel.
 611                          *
 612                          * Most browsers provide a stacktrace by default if the argument
 613                          * is a caught Error object.
 614                          *
 615                          * @since 1.26
 616                          * @param {Error|...string} msg Messages to output to console
 617                          */
 618                         log.error = console && console.error && Function.prototype.bind ?
 619                                 Function.prototype.bind.call( console.error, console ) :
 620                                 $.noop;
 621
 622                         /**
 623                          * Create a property in a host object that, when accessed, will produce
 624                          * a deprecation warning in the console with backtrace.
 625                          *
 626                          * @param {Object} obj Host object of deprecated property
 627                          * @param {string} key Name of property to create in `obj`
 628                          * @param {Mixed} val The value this property should return when accessed
 629                          * @param {string} [msg] Optional text to include in the deprecation message
 630                          */
 631                         log.deprecate = !Object.defineProperty ? function ( obj, key, val ) {
 632                                 obj[ key ] = val;
 633                         } : function ( obj, key, val, msg ) {
 634                                 msg = 'Use of "' + key + '" is deprecated.' + ( msg ? ( ' ' + msg ) : '' );
 635                                 Object.defineProperty( obj, key, {
 636                                         configurable: true,
 637                                         enumerable: true,
 638                                         get: function () {
 639                                                 mw.track( 'mw.deprecate', key );
 640                                                 mw.log.warn( msg );
 641                                                 return val;
 642                                         },
 643                                         set: function ( newVal ) {
 644                                                 mw.track( 'mw.deprecate', key );
 645                                                 mw.log.warn( msg );
 646                                                 val = newVal;
 647                                         }
 648                                 } );
 649
 650                         };
 651
 652                         return log;
 653                 }() ),
 654
 655                 /**
 656                  * Client for ResourceLoader server end point.
 657                  *
 658                  * This client is in charge of maintaining the module registry and state
 659                  * machine, initiating network (batch) requests for loading modules, as
 660                  * well as dependency resolution and execution of source code.
 661                  *
 662                  * For more information, refer to
 663                  * <https://www.mediawiki.org/wiki/ResourceLoader/Features>
 664                  *
 665                  * @class mw.loader
 666                  * @singleton
 667                  */
 668                 loader: ( function () {
 669
 670                         /**
 671                          * Fired via mw.track on various resource loading errors.
 672                          *
 673                          * @event resourceloader_exception
 674                          * @param {Error|Mixed} e The error that was thrown. Almost always an Error
 675                          *   object, but in theory module code could manually throw something else, and that
 676                          *   might also end up here.
 677                          * @param {string} [module] Name of the module which caused the error. Omitted if the
 678                          *   error is not module-related or the module cannot be easily identified due to
 679                          *   batched handling.
 680                          * @param {string} source Source of the error. Possible values:
 681                          *
 682                          *   - style: stylesheet error (only affects old IE where a special style loading method
 683                          *     is used)
 684                          *   - load-callback: exception thrown by user callback
 685                          *   - module-execute: exception thrown by module code
 686                          *   - store-eval: could not evaluate module code cached in localStorage
 687                          *   - store-localstorage-init: localStorage or JSON parse error in mw.loader.store.init
 688                          *   - store-localstorage-json: JSON conversion error in mw.loader.store.set
 689                          *   - store-localstorage-update: localStorage or JSON conversion error in mw.loader.store.update
 690                          */
 691
 692                         /**
 693                          * Fired via mw.track on resource loading error conditions.
 694                          *
 695                          * @event resourceloader_assert
 696                          * @param {string} source Source of the error. Possible values:
 697                          *
 698                          *   - bug-T59567: failed to cache script due to an Opera function -> string conversion
 699                          *     bug; see <https://phabricator.wikimedia.org/T59567> for details
 700                          */
 701
 702                         /**
 703                          * Mapping of registered modules.
 704                          *
 705                          * See #implement and #execute for exact details on support for script, style and messages.
 706                          *
 707                          * Format:
 708                          *
 709                          *     {
 710                          *         'moduleName': {
 711                          *             // From mw.loader.register()
 712                          *             'version': '########' (hash)
 713                          *             'dependencies': ['required.foo', 'bar.also', ...], (or) function () {}
 714                          *             'group': 'somegroup', (or) null
 715                          *             'source': 'local', (or) 'anotherwiki'
 716                          *             'skip': 'return !!window.Example', (or) null
 717                          *             'module': export Object
 718                          *
 719                          *             // Set from execute() or mw.loader.state()
 720                          *             'state': 'registered', 'loaded', 'loading', 'ready', 'error', or 'missing'
 721                          *
 722                          *             // Optionally added at run-time by mw.loader.implement()
 723                          *             'skipped': true
 724                          *             'script': closure, array of urls, or string
 725                          *             'style': { ... } (see #execute)
 726                          *             'messages': { 'key': 'value', ... }
 727                          *         }
 728                          *     }
 729                          *
 730                          * State machine:
 731                          *
 732                          * - `registered`:
 733                          *    The module is known to the system but not yet requested.
 734                          *    Meta data is registered via mw.loader#register. Calls to that method are
 735                          *    generated server-side by the startup module.
 736                          * - `loading`:
 737                          *    The module is requested through mw.loader (either directly or as dependency of
 738                          *    another module). The client will be fetching module contents from the server.
 739                          *    The contents are then stashed in the registry via mw.loader#implement.
 740                          * - `loaded`:
 741                          *    The module has been requested from the server and stashed via mw.loader#implement.
 742                          *    If the module has no more dependencies in-fight, the module will be executed
 743                          *    right away. Otherwise execution is deferred, controlled via #handlePending.
 744                          * - `executing`:
 745                          *    The module is being executed.
 746                          * - `ready`:
 747                          *    The module has been successfully executed.
 748                          * - `error`:
 749                          *    The module (or one of its dependencies) produced an error during execution.
 750                          * - `missing`:
 751                          *    The module was registered client-side and requested, but the server denied knowledge
 752                          *    of the module's existence.
 753                          *
 754                          * @property
 755                          * @private
 756                          */
 757                         var registry = {},
 758                                 // Mapping of sources, keyed by source-id, values are strings.
 759                                 //
 760                                 // Format:
 761                                 //
 762                                 //     {
 763                                 //         'sourceId': 'http://example.org/w/load.php'
 764                                 //     }
 765                                 //
 766                                 sources = {},
 767
 768                                 // List of modules which will be loaded as when ready
 769                                 batch = [],
 770
 771                                 // Pending queueModuleScript() requests
 772                                 handlingPendingRequests = false,
 773                                 pendingRequests = [],
 774
 775                                 // List of modules to be loaded
 776                                 queue = [],
 777
 778                                 /**
 779                                  * List of callback jobs waiting for modules to be ready.
 780                                  *
 781                                  * Jobs are created by #request() and run by #handlePending().
 782                                  *
 783                                  * Typically when a job is created for a module, the job's dependencies contain
 784                                  * both the module being requested and all its recursive dependencies.
 785                                  *
 786                                  * Format:
 787                                  *
 788                                  *     {
 789                                  *         'dependencies': [ module names ],
 790                                  *         'ready': Function callback
 791                                  *         'error': Function callback
 792                                  *     }
 793                                  *
 794                                  * @property {Object[]} jobs
 795                                  * @private
 796                                  */
 797                                 jobs = [],
 798
 799                                 // Selector cache for the marker element. Use getMarker() to get/use the marker!
 800                                 $marker = null,
 801
 802                                 // For #addEmbeddedCSS
 803                                 cssBuffer = '',
 804                                 cssBufferTimer = null,
 805                                 cssCallbacks = $.Callbacks();
 806
 807                         function getMarker() {
 808                                 if ( !$marker ) {
 809                                         // Cache
 810                                         $marker = $( 'meta[name="ResourceLoaderDynamicStyles"]' );
 811                                         if ( !$marker.length ) {
 812                                                 mw.log( 'No <meta name="ResourceLoaderDynamicStyles"> found, inserting dynamically' );
 813                                                 $marker = $( '<meta>' ).attr( 'name', 'ResourceLoaderDynamicStyles' ).appendTo( 'head' );
 814                                         }
 815                                 }
 816                                 return $marker;
 817                         }
 818
 819                         /**
 820                          * Create a new style element and add it to the DOM.
 821                          *
 822                          * @private
 823                          * @param {string} text CSS text
 824                          * @param {HTMLElement|jQuery} [nextnode=document.head] The element where the style tag
 825                          *  should be inserted before
 826                          * @return {HTMLElement} Reference to the created style element
 827                          */
 828                         function newStyleTag( text, nextnode ) {
 829                                 var s = document.createElement( 'style' );
 830                                 // Support: IE
 831                                 // Must attach to document before setting cssText (bug 33305)
 832                                 if ( nextnode ) {
 833                                         $( nextnode ).before( s );
 834                                 } else {
 835                                         document.getElementsByTagName( 'head' )[ 0 ].appendChild( s );
 836                                 }
 837                                 if ( s.styleSheet ) {
 838                                         // Support: IE6-10
 839                                         // Old IE ignores appended text nodes, access stylesheet directly.
 840                                         s.styleSheet.cssText = text;
 841                                 } else {
 842                                         // Standard behaviour
 843                                         s.appendChild( document.createTextNode( text ) );
 844                                 }
 845                                 return s;
 846                         }
 847
 848                         /**
 849                          * Add a bit of CSS text to the current browser page.
 850                          *
 851                          * The CSS will be appended to an existing ResourceLoader-created `<style>` tag
 852                          * or create a new one based on whether the given `cssText` is safe for extension.
 853                          *
 854                          * @param {string} [cssText=cssBuffer] If called without cssText,
 855                          *  the internal buffer will be inserted instead.
 856                          * @param {Function} [callback]
 857                          */
 858                         function addEmbeddedCSS( cssText, callback ) {
 859                                 var $style, styleEl, newCssText;
 860
 861                                 function fireCallbacks() {
 862                                         var oldCallbacks = cssCallbacks;
 863                                         // Reset cssCallbacks variable so it's not polluted by any calls to
 864                                         // addEmbeddedCSS() from one of the callbacks (T105973)
 865                                         cssCallbacks = $.Callbacks();
 866                                         oldCallbacks.fire().empty();
 867                                 }
 868
 869                                 if ( callback ) {
 870                                         cssCallbacks.add( callback );
 871                                 }
 872
 873                                 // Yield once before creating the <style> tag. This lets multiple stylesheets
 874                                 // accumulate into one buffer, allowing us to reduce how often new stylesheets
 875                                 // are inserted in the browser. Appending a stylesheet and waiting for the
 876                                 // browser to repaint is fairly expensive. (T47810)
 877                                 if ( cssText ) {
 878                                         // Don't extend the buffer if the item needs its own stylesheet.
 879                                         // Keywords like `@import` are only valid at the start of a stylesheet (T37562).
 880                                         if ( !cssBuffer || cssText.slice( 0, '@import'.length ) !== '@import' ) {
 881                                                 // Linebreak for somewhat distinguishable sections
 882                                                 cssBuffer += '\n' + cssText;
 883                                                 // TODO: Using requestAnimationFrame would perform better by not injecting
 884                                                 // styles while the browser is busy painting.
 885                                                 if ( !cssBufferTimer ) {
 886                                                         cssBufferTimer = setTimeout( function () {
 887                                                                 // Support: Firefox < 13
 888                                                                 // Firefox 12 has non-standard behaviour of passing a number
 889                                                                 // as first argument to a setTimeout callback.
 890                                                                 // http://benalman.com/news/2009/07/the-mysterious-firefox-settime/
 891                                                                 addEmbeddedCSS();
 892                                                         } );
 893                                                 }
 894                                                 return;
 895                                         }
 896
 897                                 // This is a scheduled flush for the buffer
 898                                 } else {
 899                                         cssBufferTimer = null;
 900                                         cssText = cssBuffer;
 901                                         cssBuffer = '';
 902                                 }
 903
 904                                 // By default, always create a new <style>. Appending text to a <style>
 905                                 // tag is bad as it means the contents have to be re-parsed (bug 45810).
 906                                 //
 907                                 // Except, of course, in IE 9 and below. In there we default to re-using and
 908                                 // appending to a <style> tag due to the IE stylesheet limit (bug 31676).
 909                                 if ( 'documentMode' in document && document.documentMode <= 9 ) {
 910
 911                                         $style = getMarker().prev();
 912                                         // Verify that the element before the marker actually is a
 913                                         // <style> tag and one that came from ResourceLoader
 914                                         // (not some other style tag or even a `<meta>` or `<script>`).
 915                                         if ( $style.data( 'ResourceLoaderDynamicStyleTag' ) ) {
 916                                                 // There's already a dynamic <style> tag present and
 917                                                 // we are able to append more to it.
 918                                                 styleEl = $style.get( 0 );
 919                                                 // Support: IE6-10
 920                                                 if ( styleEl.styleSheet ) {
 921                                                         try {
 922                                                                 // Support: IE9
 923                                                                 // We can't do styleSheet.cssText += cssText, since IE9 mangles this property on
 924                                                                 // write, dropping @media queries from the CSS text. If we read it and used its
 925                                                                 // value, we would accidentally apply @media-specific styles to all media. (T108727)
 926                                                                 if ( document.documentMode === 9 ) {
 927                                                                         newCssText = $style.data( 'ResourceLoaderDynamicStyleTag' ) + cssText;
 928                                                                         styleEl.styleSheet.cssText = newCssText;
 929                                                                         $style.data( 'ResourceLoaderDynamicStyleTag', newCssText );
 930                                                                 } else {
 931                                                                         styleEl.styleSheet.cssText += cssText;
 932                                                                 }
 933                                                         } catch ( e ) {
 934                                                                 mw.track( 'resourceloader.exception', { exception: e, source: 'stylesheet' } );
 935                                                         }
 936                                                 } else {
 937                                                         styleEl.appendChild( document.createTextNode( cssText ) );
 938                                                 }
 939                                                 fireCallbacks();
 940                                                 return;
 941                                         }
 942                                 }
 943
 944                                 $style = $( newStyleTag( cssText, getMarker() ) );
 945
 946                                 if ( document.documentMode === 9 ) {
 947                                         // Support: IE9
 948                                         // Preserve original CSS text because IE9 mangles it on write
 949                                         $style.data( 'ResourceLoaderDynamicStyleTag', cssText );
 950                                 } else {
 951                                         $style.data( 'ResourceLoaderDynamicStyleTag', true );
 952                                 }
 953
 954                                 fireCallbacks();
 955                         }
 956
 957                         /**
 958                          * @since 1.26
 959                          * @param {Array} modules List of module names
 960                          * @return {string} Hash of concatenated version hashes.
 961                          */
 962                         function getCombinedVersion( modules ) {
 963                                 var hashes = $.map( modules, function ( module ) {
 964                                         return registry[ module ].version;
 965                                 } );
 966                                 // Trim for consistency with server-side ResourceLoader::makeHash. It also helps
 967                                 // save precious space in the limited query string. Otherwise modules are more
 968                                 // likely to require multiple HTTP requests.
 969                                 return sha1( hashes.join( '' ) ).slice( 0, 12 );
 970                         }
 971
 972                         /**
 973                          * Determine whether all dependencies are in state 'ready', which means we may
 974                          * execute the module or job now.
 975                          *
 976                          * @private
 977                          * @param {Array} modules Names of modules to be checked
 978                          * @return {boolean} True if all modules are in state 'ready', false otherwise
 979                          */
 980                         function allReady( modules ) {
 981                                 var i;
 982                                 for ( i = 0; i < modules.length; i++ ) {
 983                                         if ( mw.loader.getState( modules[ i ] ) !== 'ready' ) {
 984                                                 return false;
 985                                         }
 986                                 }
 987                                 return true;
 988                         }
 989
 990                         /**
 991                          * Determine whether all dependencies are in state 'ready', which means we may
 992                          * execute the module or job now.
 993                          *
 994                          * @private
 995                          * @param {Array} modules Names of modules to be checked
 996                          * @return {boolean} True if no modules are in state 'error' or 'missing', false otherwise
 997                          */
 998                         function anyFailed( modules ) {
 999                                 var i, state;
1000                                 for ( i = 0; i < modules.length; i++ ) {
1001                                         state = mw.loader.getState( modules[ i ] );
1002                                         if ( state === 'error' || state === 'missing' ) {
1003                                                 return true;
1004                                         }
1005                                 }
1006                                 return false;
1007                         }
1008
1009                         /**
1010                          * A module has entered state 'ready', 'error', or 'missing'. Automatically update
1011                          * pending jobs and modules that depend upon this module. If the given module failed,
1012                          * propagate the 'error' state up the dependency tree. Otherwise, go ahead and execute
1013                          * all jobs/modules now having their dependencies satisfied.
1014                          *
1015                          * Jobs that depend on a failed module, will have their error callback ran (if any).
1016                          *
1017                          * @private
1018                          * @param {string} module Name of module that entered one of the states 'ready', 'error', or 'missing'.
1019                          */
1020                         function handlePending( module ) {
1021                                 var j, job, hasErrors, m, stateChange;
1022
1023                                 if ( registry[ module ].state === 'error' || registry[ module ].state === 'missing' ) {
1024                                         // If the current module failed, mark all dependent modules also as failed.
1025                                         // Iterate until steady-state to propagate the error state upwards in the
1026                                         // dependency tree.
1027                                         do {
1028                                                 stateChange = false;
1029                                                 for ( m in registry ) {
1030                                                         if ( registry[ m ].state !== 'error' && registry[ m ].state !== 'missing' ) {
1031                                                                 if ( anyFailed( registry[ m ].dependencies ) ) {
1032                                                                         registry[ m ].state = 'error';
1033                                                                         stateChange = true;
1034                                                                 }
1035                                                         }
1036                                                 }
1037                                         } while ( stateChange );
1038                                 }
1039
1040                                 // Execute all jobs whose dependencies are either all satisfied or contain at least one failed module.
1041                                 for ( j = 0; j < jobs.length; j++ ) {
1042                                         hasErrors = anyFailed( jobs[ j ].dependencies );
1043                                         if ( hasErrors || allReady( jobs[ j ].dependencies ) ) {
1044                                                 // All dependencies satisfied, or some have errors
1045                                                 job = jobs[ j ];
1046                                                 jobs.splice( j, 1 );
1047                                                 j -= 1;
1048                                                 try {
1049                                                         if ( hasErrors ) {
1050                                                                 if ( $.isFunction( job.error ) ) {
1051                                                                         job.error( new Error( 'Module ' + module + ' has failed dependencies' ), [ module ] );
1052                                                                 }
1053                                                         } else {
1054                                                                 if ( $.isFunction( job.ready ) ) {
1055                                                                         job.ready();
1056                                                                 }
1057                                                         }
1058                                                 } catch ( e ) {
1059                                                         // A user-defined callback raised an exception.
1060                                                         // Swallow it to protect our state machine!
1061                                                         mw.track( 'resourceloader.exception', { exception: e, module: module, source: 'load-callback' } );
1062                                                 }
1063                                         }
1064                                 }
1065
1066                                 if ( registry[ module ].state === 'ready' ) {
1067                                         // The current module became 'ready'. Set it in the module store, and recursively execute all
1068                                         // dependent modules that are loaded and now have all dependencies satisfied.
1069                                         mw.loader.store.set( module, registry[ module ] );
1070                                         for ( m in registry ) {
1071                                                 if ( registry[ m ].state === 'loaded' && allReady( registry[ m ].dependencies ) ) {
1072                                                         execute( m );
1073                                                 }
1074                                         }
1075                                 }
1076                         }
1077
1078                         /**
1079                          * Resolve dependencies and detect circular references.
1080                          *
1081                          * @private
1082                          * @param {string} module Name of the top-level module whose dependencies shall be
1083                          *  resolved and sorted.
1084                          * @param {Array} resolved Returns a topological sort of the given module and its
1085                          *  dependencies, such that later modules depend on earlier modules. The array
1086                          *  contains the module names. If the array contains already some module names,
1087                          *  this function appends its result to the pre-existing array.
1088                          * @param {Object} [unresolved] Hash used to track the current dependency
1089                          *  chain; used to report loops in the dependency graph.
1090                          * @throws {Error} If any unregistered module or a dependency loop is encountered
1091                          */
1092                         function sortDependencies( module, resolved, unresolved ) {
1093                                 var i, deps, skip;
1094
1095                                 if ( !hasOwn.call( registry, module ) ) {
1096                                         throw new Error( 'Unknown dependency: ' + module );
1097                                 }
1098
1099                                 if ( registry[ module ].skip !== null ) {
1100                                         /*jshint evil:true */
1101                                         skip = new Function( registry[ module ].skip );
1102                                         registry[ module ].skip = null;
1103                                         if ( skip() ) {
1104                                                 registry[ module ].skipped = true;
1105                                                 registry[ module ].dependencies = [];
1106                                                 registry[ module ].state = 'ready';
1107                                                 handlePending( module );
1108                                                 return;
1109                                         }
1110                                 }
1111
1112                                 // Resolves dynamic loader function and replaces it with its own results
1113                                 if ( $.isFunction( registry[ module ].dependencies ) ) {
1114                                         registry[ module ].dependencies = registry[ module ].dependencies();
1115                                         // Ensures the module's dependencies are always in an array
1116                                         if ( typeof registry[ module ].dependencies !== 'object' ) {
1117                                                 registry[ module ].dependencies = [ registry[ module ].dependencies ];
1118                                         }
1119                                 }
1120                                 if ( $.inArray( module, resolved ) !== -1 ) {
1121                                         // Module already resolved; nothing to do
1122                                         return;
1123                                 }
1124                                 // Create unresolved if not passed in
1125                                 if ( !unresolved ) {
1126                                         unresolved = {};
1127                                 }
1128                                 // Tracks down dependencies
1129                                 deps = registry[ module ].dependencies;
1130                                 for ( i = 0; i < deps.length; i++ ) {
1131                                         if ( $.inArray( deps[ i ], resolved ) === -1 ) {
1132                                                 if ( unresolved[ deps[ i ] ] ) {
1133                                                         throw new Error( mw.format(
1134                                                                 'Circular reference detected: $1 -> $2',
1135                                                                 module,
1136                                                                 deps[ i ]
1137                                                         ) );
1138                                                 }
1139
1140                                                 // Add to unresolved
1141                                                 unresolved[ module ] = true;
1142                                                 sortDependencies( deps[ i ], resolved, unresolved );
1143                                         }
1144                                 }
1145                                 resolved.push( module );
1146                         }
1147
1148                         /**
1149                          * Get names of module that a module depends on, in their proper dependency order.
1150                          *
1151                          * @private
1152                          * @param {string[]} modules Array of string module names
1153                          * @return {Array} List of dependencies, including 'module'.
1154                          */
1155                         function resolve( modules ) {
1156                                 var resolved = [];
1157                                 $.each( modules, function ( idx, module ) {
1158                                         sortDependencies( module, resolved );
1159                                 } );
1160                                 return resolved;
1161                         }
1162
1163                         /**
1164                          * Load and execute a script.
1165                          *
1166                          * @private
1167                          * @param {string} src URL to script, will be used as the src attribute in the script tag
1168                          * @return {jQuery.Promise}
1169                          */
1170                         function addScript( src ) {
1171                                 return $.ajax( {
1172                                         url: src,
1173                                         dataType: 'script',
1174                                         // Force jQuery behaviour to be for crossDomain. Otherwise jQuery would use
1175                                         // XHR for a same domain request instead of <script>, which changes the request
1176                                         // headers (potentially missing a cache hit), and reduces caching in general
1177                                         // since browsers cache XHR much less (if at all). And XHR means we retreive
1178                                         // text, so we'd need to $.globalEval, which then messes up line numbers.
1179                                         crossDomain: true,
1180                                         cache: true
1181                                 } );
1182                         }
1183
1184                         /**
1185                          * Queue the loading and execution of a script for a particular module.
1186                          *
1187                          * @private
1188                          * @param {string} src URL of the script
1189                          * @param {string} [moduleName] Name of currently executing module
1190                          * @return {jQuery.Promise}
1191                          */
1192                         function queueModuleScript( src, moduleName ) {
1193                                 var r = $.Deferred();
1194
1195                                 pendingRequests.push( function () {
1196                                         if ( moduleName && hasOwn.call( registry, moduleName ) ) {
1197                                                 window.require = mw.loader.require;
1198                                                 window.module = registry[ moduleName ].module;
1199                                         }
1200                                         addScript( src ).always( function () {
1201                                                 // Clear environment
1202                                                 delete window.require;
1203                                                 delete window.module;
1204                                                 r.resolve();
1205
1206                                                 // Start the next one (if any)
1207                                                 if ( pendingRequests[ 0 ] ) {
1208                                                         pendingRequests.shift()();
1209                                                 } else {
1210                                                         handlingPendingRequests = false;
1211                                                 }
1212                                         } );
1213                                 } );
1214                                 if ( !handlingPendingRequests && pendingRequests[ 0 ] ) {
1215                                         handlingPendingRequests = true;
1216                                         pendingRequests.shift()();
1217                                 }
1218                                 return r.promise();
1219                         }
1220
1221                         /**
1222                          * Utility function for execute()
1223                          *
1224                          * @ignore
1225                          */
1226                         function addLink( media, url ) {
1227                                 var el = document.createElement( 'link' );
1228                                 // Support: IE
1229                                 // Insert in document *before* setting href
1230                                 getMarker().before( el );
1231                                 el.rel = 'stylesheet';
1232                                 if ( media && media !== 'all' ) {
1233                                         el.media = media;
1234                                 }
1235                                 // If you end up here from an IE exception "SCRIPT: Invalid property value.",
1236                                 // see #addEmbeddedCSS, bug 31676, and bug 47277 for details.
1237                                 el.href = url;
1238                         }
1239
1240                         /**
1241                          * Executes a loaded module, making it ready to use
1242                          *
1243                          * @private
1244                          * @param {string} module Module name to execute
1245                          */
1246                         function execute( module ) {
1247                                 var key, value, media, i, urls, cssHandle, checkCssHandles, runScript,
1248                                         cssHandlesRegistered = false;
1249
1250                                 if ( !hasOwn.call( registry, module ) ) {
1251                                         throw new Error( 'Module has not been registered yet: ' + module );
1252                                 }
1253                                 if ( registry[ module ].state !== 'loaded' ) {
1254                                         throw new Error( 'Module in state "' + registry[ module ].state + '" may not be executed: ' + module );
1255                                 }
1256
1257                                 registry[ module ].state = 'executing';
1258
1259                                 runScript = function () {
1260                                         var script, markModuleReady, nestedAddScript, legacyWait,
1261                                                 // Expand to include dependencies since we have to exclude both legacy modules
1262                                                 // and their dependencies from the legacyWait (to prevent a circular dependency).
1263                                                 legacyModules = resolve( mw.config.get( 'wgResourceLoaderLegacyModules', [] ) );
1264                                         try {
1265                                                 script = registry[ module ].script;
1266                                                 markModuleReady = function () {
1267                                                         registry[ module ].state = 'ready';
1268                                                         handlePending( module );
1269                                                 };
1270                                                 nestedAddScript = function ( arr, callback, i ) {
1271                                                         // Recursively call queueModuleScript() in its own callback
1272                                                         // for each element of arr.
1273                                                         if ( i >= arr.length ) {
1274                                                                 // We're at the end of the array
1275                                                                 callback();
1276                                                                 return;
1277                                                         }
1278
1279                                                         queueModuleScript( arr[ i ], module ).always( function () {
1280                                                                 nestedAddScript( arr, callback, i + 1 );
1281                                                         } );
1282                                                 };
1283
1284                                                 legacyWait = ( $.inArray( module, legacyModules ) !== -1 )
1285                                                         ? $.Deferred().resolve()
1286                                                         : mw.loader.using( legacyModules );
1287
1288                                                 legacyWait.always( function () {
1289                                                         if ( $.isArray( script ) ) {
1290                                                                 nestedAddScript( script, markModuleReady, 0 );
1291                                                         } else if ( $.isFunction( script ) ) {
1292                                                                 // Pass jQuery twice so that the signature of the closure which wraps
1293                                                                 // the script can bind both '$' and 'jQuery'.
1294                                                                 script( $, $, mw.loader.require, registry[ module ].module );
1295                                                                 markModuleReady();
1296
1297                                                         } else if ( typeof script === 'string' ) {
1298                                                                 // Site and user modules are legacy scripts that run in the global scope.
1299                                                                 // This is transported as a string instead of a function to avoid needing
1300                                                                 // to use string manipulation to undo the function wrapper.
1301                                                                 if ( module === 'user' ) {
1302                                                                         // Implicit dependency on the site module. Not real dependency because
1303                                                                         // it should run after 'site' regardless of whether it succeeds or fails.
1304                                                                         mw.loader.using( 'site' ).always( function () {
1305                                                                                 $.globalEval( script );
1306                                                                                 markModuleReady();
1307                                                                         } );
1308                                                                 } else {
1309                                                                         $.globalEval( script );
1310                                                                         markModuleReady();
1311                                                                 }
1312                                                         } else {
1313                                                                 // Module without script
1314                                                                 markModuleReady();
1315                                                         }
1316                                                 } );
1317                                         } catch ( e ) {
1318                                                 // This needs to NOT use mw.log because these errors are common in production mode
1319                                                 // and not in debug mode, such as when a symbol that should be global isn't exported
1320                                                 registry[ module ].state = 'error';
1321                                                 mw.track( 'resourceloader.exception', { exception: e, module: module, source: 'module-execute' } );
1322                                                 handlePending( module );
1323                                         }
1324                                 };
1325
1326                                 // Add localizations to message system
1327                                 if ( registry[ module ].messages ) {
1328                                         mw.messages.set( registry[ module ].messages );
1329                                 }
1330
1331                                 // Initialise templates
1332                                 if ( registry[ module ].templates ) {
1333                                         mw.templates.set( module, registry[ module ].templates );
1334                                 }
1335
1336                                 // Make sure we don't run the scripts until all stylesheet insertions have completed.
1337                                 ( function () {
1338                                         var pending = 0;
1339                                         checkCssHandles = function () {
1340                                                 // cssHandlesRegistered ensures we don't take off too soon, e.g. when
1341                                                 // one of the cssHandles is fired while we're still creating more handles.
1342                                                 if ( cssHandlesRegistered && pending === 0 && runScript ) {
1343                                                         runScript();
1344                                                         runScript = undefined; // Revoke
1345                                                 }
1346                                         };
1347                                         cssHandle = function () {
1348                                                 var check = checkCssHandles;
1349                                                 pending++;
1350                                                 return function () {
1351                                                         if ( check ) {
1352                                                                 pending--;
1353                                                                 check();
1354                                                                 check = undefined; // Revoke
1355                                                         }
1356                                                 };
1357                                         };
1358                                 }() );
1359
1360                                 // Process styles (see also mw.loader.implement)
1361                                 // * back-compat: { <media>: css }
1362                                 // * back-compat: { <media>: [url, ..] }
1363                                 // * { "css": [css, ..] }
1364                                 // * { "url": { <media>: [url, ..] } }
1365                                 if ( registry[ module ].style ) {
1366                                         for ( key in registry[ module ].style ) {
1367                                                 value = registry[ module ].style[ key ];
1368                                                 media = undefined;
1369
1370                                                 if ( key !== 'url' && key !== 'css' ) {
1371                                                         // Backwards compatibility, key is a media-type
1372                                                         if ( typeof value === 'string' ) {
1373                                                                 // back-compat: { <media>: css }
1374                                                                 // Ignore 'media' because it isn't supported (nor was it used).
1375                                                                 // Strings are pre-wrapped in "@media". The media-type was just ""
1376                                                                 // (because it had to be set to something).
1377                                                                 // This is one of the reasons why this format is no longer used.
1378                                                                 addEmbeddedCSS( value, cssHandle() );
1379                                                         } else {
1380                                                                 // back-compat: { <media>: [url, ..] }
1381                                                                 media = key;
1382                                                                 key = 'bc-url';
1383                                                         }
1384                                                 }
1385
1386                                                 // Array of css strings in key 'css',
1387                                                 // or back-compat array of urls from media-type
1388                                                 if ( $.isArray( value ) ) {
1389                                                         for ( i = 0; i < value.length; i++ ) {
1390                                                                 if ( key === 'bc-url' ) {
1391                                                                         // back-compat: { <media>: [url, ..] }
1392                                                                         addLink( media, value[ i ] );
1393                                                                 } else if ( key === 'css' ) {
1394                                                                         // { "css": [css, ..] }
1395                                                                         addEmbeddedCSS( value[ i ], cssHandle() );
1396                                                                 }
1397                                                         }
1398                                                 // Not an array, but a regular object
1399                                                 // Array of urls inside media-type key
1400                                                 } else if ( typeof value === 'object' ) {
1401                                                         // { "url": { <media>: [url, ..] } }
1402                                                         for ( media in value ) {
1403                                                                 urls = value[ media ];
1404                                                                 for ( i = 0; i < urls.length; i++ ) {
1405                                                                         addLink( media, urls[ i ] );
1406                                                                 }
1407                                                         }
1408                                                 }
1409                                         }
1410                                 }
1411
1412                                 // Kick off.
1413                                 cssHandlesRegistered = true;
1414                                 checkCssHandles();
1415                         }
1416
1417                         /**
1418                          * Adds all dependencies to the queue with optional callbacks to be run
1419                          * when the dependencies are ready or fail
1420                          *
1421                          * @private
1422                          * @param {string|string[]} dependencies Module name or array of string module names
1423                          * @param {Function} [ready] Callback to execute when all dependencies are ready
1424                          * @param {Function} [error] Callback to execute when any dependency fails
1425                          */
1426                         function request( dependencies, ready, error ) {
1427                                 // Allow calling by single module name
1428                                 if ( typeof dependencies === 'string' ) {
1429                                         dependencies = [ dependencies ];
1430                                 }
1431
1432                                 // Add ready and error callbacks if they were given
1433                                 if ( ready !== undefined || error !== undefined ) {
1434                                         jobs.push( {
1435                                                 // Narrow down the list to modules that are worth waiting for
1436                                                 dependencies: $.grep( dependencies, function ( module ) {
1437                                                         var state = mw.loader.getState( module );
1438                                                         return state === 'registered' || state === 'loaded' || state === 'loading' || state === 'executing';
1439                                                 } ),
1440                                                 ready: ready,
1441                                                 error: error
1442                                         } );
1443                                 }
1444
1445                                 $.each( dependencies, function ( idx, module ) {
1446                                         var state = mw.loader.getState( module );
1447                                         // Only queue modules that are still in the initial 'registered' state
1448                                         // (not ones already loading, ready or error).
1449                                         if ( state === 'registered' && $.inArray( module, queue ) === -1 ) {
1450                                                 // Private modules must be embedded in the page. Don't bother queuing
1451                                                 // these as the server will deny them anyway (T101806).
1452                                                 if ( registry[ module ].group === 'private' ) {
1453                                                         registry[ module ].state = 'error';
1454                                                         handlePending( module );
1455                                                         return;
1456                                                 }
1457                                                 queue.push( module );
1458                                         }
1459                                 } );
1460
1461                                 mw.loader.work();
1462                         }
1463
1464                         function sortQuery( o ) {
1465                                 var key,
1466                                         sorted = {},
1467                                         a = [];
1468
1469                                 for ( key in o ) {
1470                                         if ( hasOwn.call( o, key ) ) {
1471                                                 a.push( key );
1472                                         }
1473                                 }
1474                                 a.sort();
1475                                 for ( key = 0; key < a.length; key++ ) {
1476                                         sorted[ a[ key ] ] = o[ a[ key ] ];
1477                                 }
1478                                 return sorted;
1479                         }
1480
1481                         /**
1482                          * Converts a module map of the form { foo: [ 'bar', 'baz' ], bar: [ 'baz, 'quux' ] }
1483                          * to a query string of the form foo.bar,baz|bar.baz,quux
1484                          *
1485                          * @private
1486                          */
1487                         function buildModulesString( moduleMap ) {
1488                                 var p, prefix,
1489                                         arr = [];
1490
1491                                 for ( prefix in moduleMap ) {
1492                                         p = prefix === '' ? '' : prefix + '.';
1493                                         arr.push( p + moduleMap[ prefix ].join( ',' ) );
1494                                 }
1495                                 return arr.join( '|' );
1496                         }
1497
1498                         /**
1499                          * Load modules from load.php
1500                          *
1501                          * @private
1502                          * @param {Object} moduleMap Module map, see #buildModulesString
1503                          * @param {Object} currReqBase Object with other parameters (other than 'modules') to use in the request
1504                          * @param {string} sourceLoadScript URL of load.php
1505                          */
1506                         function doRequest( moduleMap, currReqBase, sourceLoadScript ) {
1507                                 var request = $.extend(
1508                                         { modules: buildModulesString( moduleMap ) },
1509                                         currReqBase
1510                                 );
1511                                 request = sortQuery( request );
1512                                 addScript( sourceLoadScript + '?' + $.param( request ) );
1513                         }
1514
1515                         /**
1516                          * Resolve indexed dependencies.
1517                          *
1518                          * ResourceLoader uses an optimization to save space which replaces module names in
1519                          * dependency lists with the index of that module within the array of module
1520                          * registration data if it exists. The benefit is a significant reduction in the data
1521                          * size of the startup module. This function changes those dependency lists back to
1522                          * arrays of strings.
1523                          *
1524                          * @param {Array} modules Modules array
1525                          */
1526                         function resolveIndexedDependencies( modules ) {
1527                                 $.each( modules, function ( idx, module ) {
1528                                         if ( module[ 2 ] ) {
1529                                                 module[ 2 ] = $.map( module[ 2 ], function ( dep ) {
1530                                                         return typeof dep === 'number' ? modules[ dep ][ 0 ] : dep;
1531                                                 } );
1532                                         }
1533                                 } );
1534                         }
1535
1536                         /* Public Members */
1537                         return {
1538                                 /**
1539                                  * The module registry is exposed as an aid for debugging and inspecting page
1540                                  * state; it is not a public interface for modifying the registry.
1541                                  *
1542                                  * @see #registry
1543                                  * @property
1544                                  * @private
1545                                  */
1546                                 moduleRegistry: registry,
1547
1548                                 /**
1549                                  * @inheritdoc #newStyleTag
1550                                  * @method
1551                                  */
1552                                 addStyleTag: newStyleTag,
1553
1554                                 /**
1555                                  * Batch-request queued dependencies from the server.
1556                                  */
1557                                 work: function () {
1558                                         var     reqBase, splits, maxQueryLength, q, b, bSource, bGroup, bSourceGroup,
1559                                                 source, concatSource, origBatch, group, i, modules, sourceLoadScript,
1560                                                 currReqBase, currReqBaseLength, moduleMap, l,
1561                                                 lastDotIndex, prefix, suffix, bytesAdded;
1562
1563                                         // Build a list of request parameters common to all requests.
1564                                         reqBase = {
1565                                                 skin: mw.config.get( 'skin' ),
1566                                                 lang: mw.config.get( 'wgUserLanguage' ),
1567                                                 debug: mw.config.get( 'debug' )
1568                                         };
1569                                         // Split module batch by source and by group.
1570                                         splits = {};
1571                                         maxQueryLength = mw.config.get( 'wgResourceLoaderMaxQueryLength', 2000 );
1572
1573                                         // Appends a list of modules from the queue to the batch
1574                                         for ( q = 0; q < queue.length; q++ ) {
1575                                                 // Only request modules which are registered
1576                                                 if ( hasOwn.call( registry, queue[ q ] ) && registry[ queue[ q ] ].state === 'registered' ) {
1577                                                         // Prevent duplicate entries
1578                                                         if ( $.inArray( queue[ q ], batch ) === -1 ) {
1579                                                                 batch.push( queue[ q ] );
1580                                                                 // Mark registered modules as loading
1581                                                                 registry[ queue[ q ] ].state = 'loading';
1582                                                         }
1583                                                 }
1584                                         }
1585
1586                                         mw.loader.store.init();
1587                                         if ( mw.loader.store.enabled ) {
1588                                                 concatSource = [];
1589                                                 origBatch = batch;
1590                                                 batch = $.grep( batch, function ( module ) {
1591                                                         var source = mw.loader.store.get( module );
1592                                                         if ( source ) {
1593                                                                 concatSource.push( source );
1594                                                                 return false;
1595                                                         }
1596                                                         return true;
1597                                                 } );
1598                                                 try {
1599                                                         $.globalEval( concatSource.join( ';' ) );
1600                                                 } catch ( err ) {
1601                                                         // Not good, the cached mw.loader.implement calls failed! This should
1602                                                         // never happen, barring ResourceLoader bugs, browser bugs and PEBKACs.
1603                                                         // Depending on how corrupt the string is, it is likely that some
1604                                                         // modules' implement() succeeded while the ones after the error will
1605                                                         // never run and leave their modules in the 'loading' state forever.
1606
1607                                                         // Since this is an error not caused by an individual module but by
1608                                                         // something that infected the implement call itself, don't take any
1609                                                         // risks and clear everything in this cache.
1610                                                         mw.loader.store.clear();
1611                                                         // Re-add the ones still pending back to the batch and let the server
1612                                                         // repopulate these modules to the cache.
1613                                                         // This means that at most one module will be useless (the one that had
1614                                                         // the error) instead of all of them.
1615                                                         mw.track( 'resourceloader.exception', { exception: err, source: 'store-eval' } );
1616                                                         origBatch = $.grep( origBatch, function ( module ) {
1617                                                                 return registry[ module ].state === 'loading';
1618                                                         } );
1619                                                         batch = batch.concat( origBatch );
1620                                                 }
1621                                         }
1622
1623                                         // Early exit if there's nothing to load...
1624                                         if ( !batch.length ) {
1625                                                 return;
1626                                         }
1627
1628                                         // The queue has been processed into the batch, clear up the queue.
1629                                         queue = [];
1630
1631                                         // Always order modules alphabetically to help reduce cache
1632                                         // misses for otherwise identical content.
1633                                         batch.sort();
1634
1635                                         // Split batch by source and by group.
1636                                         for ( b = 0; b < batch.length; b++ ) {
1637                                                 bSource = registry[ batch[ b ] ].source;
1638                                                 bGroup = registry[ batch[ b ] ].group;
1639                                                 if ( !hasOwn.call( splits, bSource ) ) {
1640                                                         splits[ bSource ] = {};
1641                                                 }
1642                                                 if ( !hasOwn.call( splits[ bSource ], bGroup ) ) {
1643                                                         splits[ bSource ][ bGroup ] = [];
1644                                                 }
1645                                                 bSourceGroup = splits[ bSource ][ bGroup ];
1646                                                 bSourceGroup.push( batch[ b ] );
1647                                         }
1648
1649                                         // Clear the batch - this MUST happen before we append any
1650                                         // script elements to the body or it's possible that a script
1651                                         // will be locally cached, instantly load, and work the batch
1652                                         // again, all before we've cleared it causing each request to
1653                                         // include modules which are already loaded.
1654                                         batch = [];
1655
1656                                         for ( source in splits ) {
1657
1658                                                 sourceLoadScript = sources[ source ];
1659
1660                                                 for ( group in splits[ source ] ) {
1661
1662                                                         // Cache access to currently selected list of
1663                                                         // modules for this group from this source.
1664                                                         modules = splits[ source ][ group ];
1665
1666                                                         currReqBase = $.extend( {
1667                                                                 version: getCombinedVersion( modules )
1668                                                         }, reqBase );
1669                                                         // For user modules append a user name to the request.
1670                                                         if ( group === 'user' && mw.config.get( 'wgUserName' ) !== null ) {
1671                                                                 currReqBase.user = mw.config.get( 'wgUserName' );
1672                                                         }
1673                                                         currReqBaseLength = $.param( currReqBase ).length;
1674                                                         // We may need to split up the request to honor the query string length limit,
1675                                                         // so build it piece by piece.
1676                                                         l = currReqBaseLength + 9; // '&modules='.length == 9
1677
1678                                                         moduleMap = {}; // { prefix: [ suffixes ] }
1679
1680                                                         for ( i = 0; i < modules.length; i++ ) {
1681                                                                 // Determine how many bytes this module would add to the query string
1682                                                                 lastDotIndex = modules[ i ].lastIndexOf( '.' );
1683
1684                                                                 // If lastDotIndex is -1, substr() returns an empty string
1685                                                                 prefix = modules[ i ].substr( 0, lastDotIndex );
1686                                                                 suffix = modules[ i ].slice( lastDotIndex + 1 );
1687
1688                                                                 bytesAdded = hasOwn.call( moduleMap, prefix )
1689                                                                         ? suffix.length + 3 // '%2C'.length == 3
1690                                                                         : modules[ i ].length + 3; // '%7C'.length == 3
1691
1692                                                                 // If the request would become too long, create a new one,
1693                                                                 // but don't create empty requests
1694                                                                 if ( maxQueryLength > 0 && !$.isEmptyObject( moduleMap ) && l + bytesAdded > maxQueryLength ) {
1695                                                                         // This request would become too long, create a new one
1696                                                                         // and fire off the old one
1697                                                                         doRequest( moduleMap, currReqBase, sourceLoadScript );
1698                                                                         moduleMap = {};
1699                                                                         l = currReqBaseLength + 9;
1700                                                                         mw.track( 'resourceloader.splitRequest', { maxQueryLength: maxQueryLength } );
1701                                                                 }
1702                                                                 if ( !hasOwn.call( moduleMap, prefix ) ) {
1703                                                                         moduleMap[ prefix ] = [];
1704                                                                 }
1705                                                                 moduleMap[ prefix ].push( suffix );
1706                                                                 l += bytesAdded;
1707                                                         }
1708                                                         // If there's anything left in moduleMap, request that too
1709                                                         if ( !$.isEmptyObject( moduleMap ) ) {
1710                                                                 doRequest( moduleMap, currReqBase, sourceLoadScript );
1711                                                         }
1712                                                 }
1713                                         }
1714                                 },
1715
1716                                 /**
1717                                  * Register a source.
1718                                  *
1719                                  * The #work() method will use this information to split up requests by source.
1720                                  *
1721                                  *     mw.loader.addSource( 'mediawikiwiki', '//www.mediawiki.org/w/load.php' );
1722                                  *
1723                                  * @param {string|Object} id Source ID, or object mapping ids to load urls
1724                                  * @param {string} loadUrl Url to a load.php end point
1725                                  * @throws {Error} If source id is already registered
1726                                  */
1727                                 addSource: function ( id, loadUrl ) {
1728                                         var source;
1729                                         // Allow multiple additions
1730                                         if ( typeof id === 'object' ) {
1731                                                 for ( source in id ) {
1732                                                         mw.loader.addSource( source, id[ source ] );
1733                                                 }
1734                                                 return;
1735                                         }
1736
1737                                         if ( hasOwn.call( sources, id ) ) {
1738                                                 throw new Error( 'source already registered: ' + id );
1739                                         }
1740
1741                                         sources[ id ] = loadUrl;
1742                                 },
1743
1744                                 /**
1745                                  * Register a module, letting the system know about it and its properties.
1746                                  *
1747                                  * The startup modules contain calls to this method.
1748                                  *
1749                                  * When using multiple module registration by passing an array, dependencies that
1750                                  * are specified as references to modules within the array will be resolved before
1751                                  * the modules are registered.
1752                                  *
1753                                  * @param {string|Array} module Module name or array of arrays, each containing
1754                                  *  a list of arguments compatible with this method
1755                                  * @param {string|number} version Module version hash (falls backs to empty string)
1756                                  *  Can also be a number (timestamp) for compatibility with MediaWiki 1.25 and earlier.
1757                                  * @param {string|Array|Function} dependencies One string or array of strings of module
1758                                  *  names on which this module depends, or a function that returns that array.
1759                                  * @param {string} [group=null] Group which the module is in
1760                                  * @param {string} [source='local'] Name of the source
1761                                  * @param {string} [skip=null] Script body of the skip function
1762                                  */
1763                                 register: function ( module, version, dependencies, group, source, skip ) {
1764                                         var i;
1765                                         // Allow multiple registration
1766                                         if ( typeof module === 'object' ) {
1767                                                 resolveIndexedDependencies( module );
1768                                                 for ( i = 0; i < module.length; i++ ) {
1769                                                         // module is an array of module names
1770                                                         if ( typeof module[ i ] === 'string' ) {
1771                                                                 mw.loader.register( module[ i ] );
1772                                                         // module is an array of arrays
1773                                                         } else if ( typeof module[ i ] === 'object' ) {
1774                                                                 mw.loader.register.apply( mw.loader, module[ i ] );
1775                                                         }
1776                                                 }
1777                                                 return;
1778                                         }
1779                                         // Validate input
1780                                         if ( typeof module !== 'string' ) {
1781                                                 throw new Error( 'module must be a string, not a ' + typeof module );
1782                                         }
1783                                         if ( hasOwn.call( registry, module ) ) {
1784                                                 throw new Error( 'module already registered: ' + module );
1785                                         }
1786                                         // List the module as registered
1787                                         registry[ module ] = {
1788                                                 // Exposed to execute() for mw.loader.implement() closures.
1789                                                 // Import happens via require().
1790                                                 module: {
1791                                                         exports: {}
1792                                                 },
1793                                                 version: version !== undefined ? String( version ) : '',
1794                                                 dependencies: [],
1795                                                 group: typeof group === 'string' ? group : null,
1796                                                 source: typeof source === 'string' ? source : 'local',
1797                                                 state: 'registered',
1798                                                 skip: typeof skip === 'string' ? skip : null
1799                                         };
1800                                         if ( typeof dependencies === 'string' ) {
1801                                                 // Allow dependencies to be given as a single module name
1802                                                 registry[ module ].dependencies = [ dependencies ];
1803                                         } else if ( typeof dependencies === 'object' || $.isFunction( dependencies ) ) {
1804                                                 // Allow dependencies to be given as an array of module names
1805                                                 // or a function which returns an array
1806                                                 registry[ module ].dependencies = dependencies;
1807                                         }
1808                                 },
1809
1810                                 /**
1811                                  * Implement a module given the components that make up the module.
1812                                  *
1813                                  * When #load or #using requests one or more modules, the server
1814                                  * response contain calls to this function.
1815                                  *
1816                                  * @param {string} module Name of module
1817                                  * @param {Function|Array} [script] Function with module code or Array of URLs to
1818                                  *  be used as the src attribute of a new `<script>` tag.
1819                                  * @param {Object} [style] Should follow one of the following patterns:
1820                                  *
1821                                  *     { "css": [css, ..] }
1822                                  *     { "url": { <media>: [url, ..] } }
1823                                  *
1824                                  * And for backwards compatibility (needs to be supported forever due to caching):
1825                                  *
1826                                  *     { <media>: css }
1827                                  *     { <media>: [url, ..] }
1828                                  *
1829                                  * The reason css strings are not concatenated anymore is bug 31676. We now check
1830                                  * whether it's safe to extend the stylesheet.
1831                                  *
1832                                  * @param {Object} [messages] List of key/value pairs to be added to mw#messages.
1833                                  * @param {Object} [templates] List of key/value pairs to be added to mw#templates.
1834                                  */
1835                                 implement: function ( module, script, style, messages, templates ) {
1836                                         // Validate input
1837                                         if ( typeof module !== 'string' ) {
1838                                                 throw new Error( 'module must be of type string, not ' + typeof module );
1839                                         }
1840                                         if ( script && !$.isFunction( script ) && !$.isArray( script ) && typeof script !== 'string' ) {
1841                                                 throw new Error( 'script must be of type function, array, or script; not ' + typeof script );
1842                                         }
1843                                         if ( style && !$.isPlainObject( style ) ) {
1844                                                 throw new Error( 'style must be of type object, not ' + typeof style );
1845                                         }
1846                                         if ( messages && !$.isPlainObject( messages ) ) {
1847                                                 throw new Error( 'messages must be of type object, not a ' + typeof messages );
1848                                         }
1849                                         if ( templates && !$.isPlainObject( templates ) ) {
1850                                                 throw new Error( 'templates must be of type object, not a ' + typeof templates );
1851                                         }
1852                                         // Automatically register module
1853                                         if ( !hasOwn.call( registry, module ) ) {
1854                                                 mw.loader.register( module );
1855                                         }
1856                                         // Check for duplicate implementation
1857                                         if ( hasOwn.call( registry, module ) && registry[ module ].script !== undefined ) {
1858                                                 throw new Error( 'module already implemented: ' + module );
1859                                         }
1860                                         // Attach components
1861                                         registry[ module ].script = script || null;
1862                                         registry[ module ].style = style || null;
1863                                         registry[ module ].messages = messages || null;
1864                                         registry[ module ].templates = templates || null;
1865                                         // The module may already have been marked as erroneous
1866                                         if ( $.inArray( registry[ module ].state, [ 'error', 'missing' ] ) === -1 ) {
1867                                                 registry[ module ].state = 'loaded';
1868                                                 if ( allReady( registry[ module ].dependencies ) ) {
1869                                                         execute( module );
1870                                                 }
1871                                         }
1872                                 },
1873
1874                                 /**
1875                                  * Execute a function as soon as one or more required modules are ready.
1876                                  *
1877                                  * Example of inline dependency on OOjs:
1878                                  *
1879                                  *     mw.loader.using( 'oojs', function () {
1880                                  *         OO.compare( [ 1 ], [ 1 ] );
1881                                  *     } );
1882                                  *
1883                                  * @param {string|Array} dependencies Module name or array of modules names the callback
1884                                  *  dependends on to be ready before executing
1885                                  * @param {Function} [ready] Callback to execute when all dependencies are ready
1886                                  * @param {Function} [error] Callback to execute if one or more dependencies failed
1887                                  * @return {jQuery.Promise}
1888                                  * @since 1.23 this returns a promise
1889                                  */
1890                                 using: function ( dependencies, ready, error ) {
1891                                         var deferred = $.Deferred();
1892
1893                                         // Allow calling with a single dependency as a string
1894                                         if ( typeof dependencies === 'string' ) {
1895                                                 dependencies = [ dependencies ];
1896                                         } else if ( !$.isArray( dependencies ) ) {
1897                                                 // Invalid input
1898                                                 throw new Error( 'Dependencies must be a string or an array' );
1899                                         }
1900
1901                                         if ( ready ) {
1902                                                 deferred.done( ready );
1903                                         }
1904                                         if ( error ) {
1905                                                 deferred.fail( error );
1906                                         }
1907
1908                                         // Resolve entire dependency map
1909                                         dependencies = resolve( dependencies );
1910                                         if ( allReady( dependencies ) ) {
1911                                                 // Run ready immediately
1912                                                 deferred.resolve();
1913                                         } else if ( anyFailed( dependencies ) ) {
1914                                                 // Execute error immediately if any dependencies have errors
1915                                                 deferred.reject(
1916                                                         new Error( 'One or more dependencies failed to load' ),
1917                                                         dependencies
1918                                                 );
1919                                         } else {
1920                                                 // Not all dependencies are ready: queue up a request
1921                                                 request( dependencies, deferred.resolve, deferred.reject );
1922                                         }
1923
1924                                         return deferred.promise();
1925                                 },
1926
1927                                 /**
1928                                  * Load an external script or one or more modules.
1929                                  *
1930                                  * @param {string|Array} modules Either the name of a module, array of modules,
1931                                  *  or a URL of an external script or style
1932                                  * @param {string} [type='text/javascript'] MIME type to use if calling with a URL of an
1933                                  *  external script or style; acceptable values are "text/css" and
1934                                  *  "text/javascript"; if no type is provided, text/javascript is assumed.
1935                                  */
1936                                 load: function ( modules, type ) {
1937                                         var filtered, l;
1938
1939                                         // Validate input
1940                                         if ( typeof modules !== 'object' && typeof modules !== 'string' ) {
1941                                                 throw new Error( 'modules must be a string or an array, not a ' + typeof modules );
1942                                         }
1943                                         // Allow calling with a url or single dependency as a string
1944                                         if ( typeof modules === 'string' ) {
1945                                                 // "https://example.org/x.js", "http://example.org/x.js", "//example.org/x.js", "/x.js"
1946                                                 if ( /^(https?:)?\/?\//.test( modules ) ) {
1947                                                         if ( type === 'text/css' ) {
1948                                                                 // Support: IE 7-8
1949                                                                 // Use properties instead of attributes as IE throws security
1950                                                                 // warnings when inserting a <link> tag with a protocol-relative
1951                                                                 // URL set though attributes - when on HTTPS. See bug 41331.
1952                                                                 l = document.createElement( 'link' );
1953                                                                 l.rel = 'stylesheet';
1954                                                                 l.href = modules;
1955                                                                 $( 'head' ).append( l );
1956                                                                 return;
1957                                                         }
1958                                                         if ( type === 'text/javascript' || type === undefined ) {
1959                                                                 addScript( modules );
1960                                                                 return;
1961                                                         }
1962                                                         // Unknown type
1963                                                         throw new Error( 'invalid type for external url, must be text/css or text/javascript. not ' + type );
1964                                                 }
1965                                                 // Called with single module
1966                                                 modules = [ modules ];
1967                                         }
1968
1969                                         // Filter out undefined modules, otherwise resolve() will throw
1970                                         // an exception for trying to load an undefined module.
1971                                         // Undefined modules are acceptable here in load(), because load() takes
1972                                         // an array of unrelated modules, whereas the modules passed to
1973                                         // using() are related and must all be loaded.
1974                                         filtered = $.grep( modules, function ( module ) {
1975                                                 var state = mw.loader.getState( module );
1976                                                 return state !== null && state !== 'error' && state !== 'missing';
1977                                         } );
1978
1979                                         if ( filtered.length === 0 ) {
1980                                                 return;
1981                                         }
1982                                         // Resolve entire dependency map
1983                                         filtered = resolve( filtered );
1984                                         // If all modules are ready, or if any modules have errors, nothing to be done.
1985                                         if ( allReady( filtered ) || anyFailed( filtered ) ) {
1986                                                 return;
1987                                         }
1988                                         // Since some modules are not yet ready, queue up a request.
1989                                         request( filtered, undefined, undefined );
1990                                 },
1991
1992                                 /**
1993                                  * Change the state of one or more modules.
1994                                  *
1995                                  * @param {string|Object} module Module name or object of module name/state pairs
1996                                  * @param {string} state State name
1997                                  */
1998                                 state: function ( module, state ) {
1999                                         var m;
2000
2001                                         if ( typeof module === 'object' ) {
2002                                                 for ( m in module ) {
2003                                                         mw.loader.state( m, module[ m ] );
2004                                                 }
2005                                                 return;
2006                                         }
2007                                         if ( !hasOwn.call( registry, module ) ) {
2008                                                 mw.loader.register( module );
2009                                         }
2010                                         if ( $.inArray( state, [ 'ready', 'error', 'missing' ] ) !== -1
2011                                                 && registry[ module ].state !== state ) {
2012                                                 // Make sure pending modules depending on this one get executed if their
2013                                                 // dependencies are now fulfilled!
2014                                                 registry[ module ].state = state;
2015                                                 handlePending( module );
2016                                         } else {
2017                                                 registry[ module ].state = state;
2018                                         }
2019                                 },
2020
2021                                 /**
2022                                  * Get the version of a module.
2023                                  *
2024                                  * @param {string} module Name of module
2025                                  * @return {string|null} The version, or null if the module (or its version) is not
2026                                  *  in the registry.
2027                                  */
2028                                 getVersion: function ( module ) {
2029                                         if ( !hasOwn.call( registry, module ) || registry[ module ].version === undefined ) {
2030                                                 return null;
2031                                         }
2032                                         return registry[ module ].version;
2033                                 },
2034
2035                                 /**
2036                                  * Get the state of a module.
2037                                  *
2038                                  * @param {string} module Name of module
2039                                  * @return {string|null} The state, or null if the module (or its state) is not
2040                                  *  in the registry.
2041                                  */
2042                                 getState: function ( module ) {
2043                                         if ( !hasOwn.call( registry, module ) || registry[ module ].state === undefined ) {
2044                                                 return null;
2045                                         }
2046                                         return registry[ module ].state;
2047                                 },
2048
2049                                 /**
2050                                  * Get the names of all registered modules.
2051                                  *
2052                                  * @return {Array}
2053                                  */
2054                                 getModuleNames: function () {
2055                                         return $.map( registry, function ( i, key ) {
2056                                                 return key;
2057                                         } );
2058                                 },
2059
2060                                 /**
2061                                  * Get the exported value of a module.
2062                                  *
2063                                  * Module provide this value via their local `module.exports`.
2064                                  *
2065                                  * @since 1.27
2066                                  * @return {Array}
2067                                  */
2068                                 require: function ( moduleName ) {
2069                                         var state = mw.loader.getState( moduleName );
2070
2071                                         // Only ready mudules can be required
2072                                         if ( state !== 'ready' ) {
2073                                                 // Module may've forgotten to declare a dependency
2074                                                 throw new Error( 'Module "' + moduleName + '" is not loaded.' );
2075                                         }
2076
2077                                         return registry[ moduleName ].module.exports;
2078                                 },
2079
2080                                 /**
2081                                  * @inheritdoc mw.inspect#runReports
2082                                  * @method
2083                                  */
2084                                 inspect: function () {
2085                                         var args = slice.call( arguments );
2086                                         mw.loader.using( 'mediawiki.inspect', function () {
2087                                                 mw.inspect.runReports.apply( mw.inspect, args );
2088                                         } );
2089                                 },
2090
2091                                 /**
2092                                  * On browsers that implement the localStorage API, the module store serves as a
2093                                  * smart complement to the browser cache. Unlike the browser cache, the module store
2094                                  * can slice a concatenated response from ResourceLoader into its constituent
2095                                  * modules and cache each of them separately, using each module's versioning scheme
2096                                  * to determine when the cache should be invalidated.
2097                                  *
2098                                  * @singleton
2099                                  * @class mw.loader.store
2100                                  */
2101                                 store: {
2102                                         // Whether the store is in use on this page.
2103                                         enabled: null,
2104
2105                                         MODULE_SIZE_MAX: 100 * 1000,
2106
2107                                         // The contents of the store, mapping '[module name]@[version]' keys
2108                                         // to module implementations.
2109                                         items: {},
2110
2111                                         // Cache hit stats
2112                                         stats: { hits: 0, misses: 0, expired: 0 },
2113
2114                                         /**
2115                                          * Construct a JSON-serializable object representing the content of the store.
2116                                          *
2117                                          * @return {Object} Module store contents.
2118                                          */
2119                                         toJSON: function () {
2120                                                 return { items: mw.loader.store.items, vary: mw.loader.store.getVary() };
2121                                         },
2122
2123                                         /**
2124                                          * Get the localStorage key for the entire module store. The key references
2125                                          * $wgDBname to prevent clashes between wikis which share a common host.
2126                                          *
2127                                          * @return {string} localStorage item key
2128                                          */
2129                                         getStoreKey: function () {
2130                                                 return 'MediaWikiModuleStore:' + mw.config.get( 'wgDBname' );
2131                                         },
2132
2133                                         /**
2134                                          * Get a key on which to vary the module cache.
2135                                          *
2136                                          * @return {string} String of concatenated vary conditions.
2137                                          */
2138                                         getVary: function () {
2139                                                 return [
2140                                                         mw.config.get( 'skin' ),
2141                                                         mw.config.get( 'wgResourceLoaderStorageVersion' ),
2142                                                         mw.config.get( 'wgUserLanguage' )
2143                                                 ].join( ':' );
2144                                         },
2145
2146                                         /**
2147                                          * Get a key for a specific module. The key format is '[name]@[version]'.
2148                                          *
2149                                          * @param {string} module Module name
2150                                          * @return {string|null} Module key or null if module does not exist
2151                                          */
2152                                         getModuleKey: function ( module ) {
2153                                                 return hasOwn.call( registry, module ) ?
2154                                                         ( module + '@' + registry[ module ].version ) : null;
2155                                         },
2156
2157                                         /**
2158                                          * Initialize the store.
2159                                          *
2160                                          * Retrieves store from localStorage and (if successfully retrieved) decoding
2161                                          * the stored JSON value to a plain object.
2162                                          *
2163                                          * The try / catch block is used for JSON & localStorage feature detection.
2164                                          * See the in-line documentation for Modernizr's localStorage feature detection
2165                                          * code for a full account of why we need a try / catch:
2166                                          * <https://github.com/Modernizr/Modernizr/blob/v2.7.1/modernizr.js#L771-L796>.
2167                                          */
2168                                         init: function () {
2169                                                 var raw, data;
2170
2171                                                 if ( mw.loader.store.enabled !== null ) {
2172                                                         // Init already ran
2173                                                         return;
2174                                                 }
2175
2176                                                 if (
2177                                                         // Disabled because localStorage quotas are tight and (in Firefox's case)
2178                                                         // shared by multiple origins.
2179                                                         // See T66721, and <https://bugzilla.mozilla.org/show_bug.cgi?id=1064466>.
2180                                                         /Firefox|Opera/.test( navigator.userAgent ) ||
2181
2182                                                         // Disabled by configuration.
2183                                                         !mw.config.get( 'wgResourceLoaderStorageEnabled' )
2184                                                 ) {
2185                                                         // Clear any previous store to free up space. (T66721)
2186                                                         mw.loader.store.clear();
2187                                                         mw.loader.store.enabled = false;
2188                                                         return;
2189                                                 }
2190                                                 if ( mw.config.get( 'debug' ) ) {
2191                                                         // Disable module store in debug mode
2192                                                         mw.loader.store.enabled = false;
2193                                                         return;
2194                                                 }
2195
2196                                                 try {
2197                                                         raw = localStorage.getItem( mw.loader.store.getStoreKey() );
2198                                                         // If we get here, localStorage is available; mark enabled
2199                                                         mw.loader.store.enabled = true;
2200                                                         data = JSON.parse( raw );
2201                                                         if ( data && typeof data.items === 'object' && data.vary === mw.loader.store.getVary() ) {
2202                                                                 mw.loader.store.items = data.items;
2203                                                                 return;
2204                                                         }
2205                                                 } catch ( e ) {
2206                                                         mw.track( 'resourceloader.exception', { exception: e, source: 'store-localstorage-init' } );
2207                                                 }
2208
2209                                                 if ( raw === undefined ) {
2210                                                         // localStorage failed; disable store
2211                                                         mw.loader.store.enabled = false;
2212                                                 } else {
2213                                                         mw.loader.store.update();
2214                                                 }
2215                                         },
2216
2217                                         /**
2218                                          * Retrieve a module from the store and update cache hit stats.
2219                                          *
2220                                          * @param {string} module Module name
2221                                          * @return {string|boolean} Module implementation or false if unavailable
2222                                          */
2223                                         get: function ( module ) {
2224                                                 var key;
2225
2226                                                 if ( !mw.loader.store.enabled ) {
2227                                                         return false;
2228                                                 }
2229
2230                                                 key = mw.loader.store.getModuleKey( module );
2231                                                 if ( key in mw.loader.store.items ) {
2232                                                         mw.loader.store.stats.hits++;
2233                                                         return mw.loader.store.items[ key ];
2234                                                 }
2235                                                 mw.loader.store.stats.misses++;
2236                                                 return false;
2237                                         },
2238
2239                                         /**
2240                                          * Stringify a module and queue it for storage.
2241                                          *
2242                                          * @param {string} module Module name
2243                                          * @param {Object} descriptor The module's descriptor as set in the registry
2244                                          */
2245                                         set: function ( module, descriptor ) {
2246                                                 var args, key, src;
2247
2248                                                 if ( !mw.loader.store.enabled ) {
2249                                                         return false;
2250                                                 }
2251
2252                                                 key = mw.loader.store.getModuleKey( module );
2253
2254                                                 if (
2255                                                         // Already stored a copy of this exact version
2256                                                         key in mw.loader.store.items ||
2257                                                         // Module failed to load
2258                                                         descriptor.state !== 'ready' ||
2259                                                         // Unversioned, private, or site-/user-specific
2260                                                         ( !descriptor.version || $.inArray( descriptor.group, [ 'private', 'user' ] ) !== -1 ) ||
2261                                                         // Partial descriptor
2262                                                         $.inArray( undefined, [ descriptor.script, descriptor.style,
2263                                                                         descriptor.messages, descriptor.templates ] ) !== -1
2264                                                 ) {
2265                                                         // Decline to store
2266                                                         return false;
2267                                                 }
2268
2269                                                 try {
2270                                                         args = [
2271                                                                 JSON.stringify( module ),
2272                                                                 typeof descriptor.script === 'function' ?
2273                                                                         String( descriptor.script ) :
2274                                                                         JSON.stringify( descriptor.script ),
2275                                                                 JSON.stringify( descriptor.style ),
2276                                                                 JSON.stringify( descriptor.messages ),
2277                                                                 JSON.stringify( descriptor.templates )
2278                                                         ];
2279                                                         // Attempted workaround for a possible Opera bug (bug T59567).
2280                                                         // This regex should never match under sane conditions.
2281                                                         if ( /^\s*\(/.test( args[ 1 ] ) ) {
2282                                                                 args[ 1 ] = 'function' + args[ 1 ];
2283                                                                 mw.track( 'resourceloader.assert', { source: 'bug-T59567' } );
2284                                                         }
2285                                                 } catch ( e ) {
2286                                                         mw.track( 'resourceloader.exception', { exception: e, source: 'store-localstorage-json' } );
2287                                                         return;
2288                                                 }
2289
2290                                                 src = 'mw.loader.implement(' + args.join( ',' ) + ');';
2291                                                 if ( src.length > mw.loader.store.MODULE_SIZE_MAX ) {
2292                                                         return false;
2293                                                 }
2294                                                 mw.loader.store.items[ key ] = src;
2295                                                 mw.loader.store.update();
2296                                         },
2297
2298                                         /**
2299                                          * Iterate through the module store, removing any item that does not correspond
2300                                          * (in name and version) to an item in the module registry.
2301                                          */
2302                                         prune: function () {
2303                                                 var key, module;
2304
2305                                                 if ( !mw.loader.store.enabled ) {
2306                                                         return false;
2307                                                 }
2308
2309                                                 for ( key in mw.loader.store.items ) {
2310                                                         module = key.slice( 0, key.indexOf( '@' ) );
2311                                                         if ( mw.loader.store.getModuleKey( module ) !== key ) {
2312                                                                 mw.loader.store.stats.expired++;
2313                                                                 delete mw.loader.store.items[ key ];
2314                                                         } else if ( mw.loader.store.items[ key ].length > mw.loader.store.MODULE_SIZE_MAX ) {
2315                                                                 // This value predates the enforcement of a size limit on cached modules.
2316                                                                 delete mw.loader.store.items[ key ];
2317                                                         }
2318                                                 }
2319                                         },
2320
2321                                         /**
2322                                          * Clear the entire module store right now.
2323                                          */
2324                                         clear: function () {
2325                                                 mw.loader.store.items = {};
2326                                                 try {
2327                                                         localStorage.removeItem( mw.loader.store.getStoreKey() );
2328                                                 } catch ( ignored ) {}
2329                                         },
2330
2331                                         /**
2332                                          * Sync in-memory store back to localStorage.
2333                                          *
2334                                          * This function debounces updates. When called with a flush already pending,
2335                                          * the call is coalesced into the pending update. The call to
2336                                          * localStorage.setItem will be naturally deferred until the page is quiescent.
2337                                          *
2338                                          * Because localStorage is shared by all pages from the same origin, if multiple
2339                                          * pages are loaded with different module sets, the possibility exists that
2340                                          * modules saved by one page will be clobbered by another. But the impact would
2341                                          * be minor and the problem would be corrected by subsequent page views.
2342                                          *
2343                                          * @method
2344                                          */
2345                                         update: ( function () {
2346                                                 var hasPendingWrite = false;
2347
2348                                                 function flushWrites() {
2349                                                         var data, key;
2350                                                         if ( !hasPendingWrite || !mw.loader.store.enabled ) {
2351                                                                 return;
2352                                                         }
2353
2354                                                         mw.loader.store.prune();
2355                                                         key = mw.loader.store.getStoreKey();
2356                                                         try {
2357                                                                 // Replacing the content of the module store might fail if the new
2358                                                                 // contents would exceed the browser's localStorage size limit. To
2359                                                                 // avoid clogging the browser with stale data, always remove the old
2360                                                                 // value before attempting to set the new one.
2361                                                                 localStorage.removeItem( key );
2362                                                                 data = JSON.stringify( mw.loader.store );
2363                                                                 localStorage.setItem( key, data );
2364                                                         } catch ( e ) {
2365                                                                 mw.track( 'resourceloader.exception', { exception: e, source: 'store-localstorage-update' } );
2366                                                         }
2367
2368                                                         hasPendingWrite = false;
2369                                                 }
2370
2371                                                 return function () {
2372                                                         if ( !hasPendingWrite ) {
2373                                                                 hasPendingWrite = true;
2374                                                                 mw.requestIdleCallback( flushWrites );
2375                                                         }
2376                                                 };
2377                                         }() )
2378                                 }
2379                         };
2380                 }() ),
2381
2382                 /**
2383                  * HTML construction helper functions
2384                  *
2385                  *     @example
2386                  *
2387                  *     var Html, output;
2388                  *
2389                  *     Html = mw.html;
2390                  *     output = Html.element( 'div', {}, new Html.Raw(
2391                  *         Html.element( 'img', { src: '<' } )
2392                  *     ) );
2393                  *     mw.log( output ); // <div><img src="&lt;"/></div>
2394                  *
2395                  * @class mw.html
2396                  * @singleton
2397                  */
2398                 html: ( function () {
2399                         function escapeCallback( s ) {
2400                                 switch ( s ) {
2401                                         case '\'':
2402                                                 return '&#039;';
2403                                         case '"':
2404                                                 return '&quot;';
2405                                         case '<':
2406                                                 return '&lt;';
2407                                         case '>':
2408                                                 return '&gt;';
2409                                         case '&':
2410                                                 return '&amp;';
2411                                 }
2412                         }
2413
2414                         return {
2415                                 /**
2416                                  * Escape a string for HTML.
2417                                  *
2418                                  * Converts special characters to HTML entities.
2419                                  *
2420                                  *     mw.html.escape( '< > \' & "' );
2421                                  *     // Returns &lt; &gt; &#039; &amp; &quot;
2422                                  *
2423                                  * @param {string} s The string to escape
2424                                  * @return {string} HTML
2425                                  */
2426                                 escape: function ( s ) {
2427                                         return s.replace( /['"<>&]/g, escapeCallback );
2428                                 },
2429
2430                                 /**
2431                                  * Create an HTML element string, with safe escaping.
2432                                  *
2433                                  * @param {string} name The tag name.
2434                                  * @param {Object} [attrs] An object with members mapping element names to values
2435                                  * @param {string|mw.html.Raw|mw.html.Cdata|null} [contents=null] The contents of the element.
2436                                  *
2437                                  *  - string: Text to be escaped.
2438                                  *  - null: The element is treated as void with short closing form, e.g. `<br/>`.
2439                                  *  - this.Raw: The raw value is directly included.
2440                                  *  - this.Cdata: The raw value is directly included. An exception is
2441                                  *    thrown if it contains any illegal ETAGO delimiter.
2442                                  *    See <http://www.w3.org/TR/html401/appendix/notes.html#h-B.3.2>.
2443                                  * @return {string} HTML
2444                                  */
2445                                 element: function ( name, attrs, contents ) {
2446                                         var v, attrName, s = '<' + name;
2447
2448                                         if ( attrs ) {
2449                                                 for ( attrName in attrs ) {
2450                                                         v = attrs[ attrName ];
2451                                                         // Convert name=true, to name=name
2452                                                         if ( v === true ) {
2453                                                                 v = attrName;
2454                                                         // Skip name=false
2455                                                         } else if ( v === false ) {
2456                                                                 continue;
2457                                                         }
2458                                                         s += ' ' + attrName + '="' + this.escape( String( v ) ) + '"';
2459                                                 }
2460                                         }
2461                                         if ( contents === undefined || contents === null ) {
2462                                                 // Self close tag
2463                                                 s += '/>';
2464                                                 return s;
2465                                         }
2466                                         // Regular open tag
2467                                         s += '>';
2468                                         switch ( typeof contents ) {
2469                                                 case 'string':
2470                                                         // Escaped
2471                                                         s += this.escape( contents );
2472                                                         break;
2473                                                 case 'number':
2474                                                 case 'boolean':
2475                                                         // Convert to string
2476                                                         s += String( contents );
2477                                                         break;
2478                                                 default:
2479                                                         if ( contents instanceof this.Raw ) {
2480                                                                 // Raw HTML inclusion
2481                                                                 s += contents.value;
2482                                                         } else if ( contents instanceof this.Cdata ) {
2483                                                                 // CDATA
2484                                                                 if ( /<\/[a-zA-z]/.test( contents.value ) ) {
2485                                                                         throw new Error( 'mw.html.element: Illegal end tag found in CDATA' );
2486                                                                 }
2487                                                                 s += contents.value;
2488                                                         } else {
2489                                                                 throw new Error( 'mw.html.element: Invalid type of contents' );
2490                                                         }
2491                                         }
2492                                         s += '</' + name + '>';
2493                                         return s;
2494                                 },
2495
2496                                 /**
2497                                  * Wrapper object for raw HTML passed to mw.html.element().
2498                                  *
2499                                  * @class mw.html.Raw
2500                                  */
2501                                 Raw: function ( value ) {
2502                                         this.value = value;
2503                                 },
2504
2505                                 /**
2506                                  * Wrapper object for CDATA element contents passed to mw.html.element()
2507                                  *
2508                                  * @class mw.html.Cdata
2509                                  */
2510                                 Cdata: function ( value ) {
2511                                         this.value = value;
2512                                 }
2513                         };
2514                 }() ),
2515
2516                 // Skeleton user object, extended by the 'mediawiki.user' module.
2517                 /**
2518                  * @class mw.user
2519                  * @singleton
2520                  */
2521                 user: {
2522                         /**
2523                          * @property {mw.Map}
2524                          */
2525                         options: new Map(),
2526                         /**
2527                          * @property {mw.Map}
2528                          */
2529                         tokens: new Map()
2530                 },
2531
2532                 // OOUI widgets specific to MediaWiki
2533                 widgets: {},
2534
2535                 /**
2536                  * Registry and firing of events.
2537                  *
2538                  * MediaWiki has various interface components that are extended, enhanced
2539                  * or manipulated in some other way by extensions, gadgets and even
2540                  * in core itself.
2541                  *
2542                  * This framework helps streamlining the timing of when these other
2543                  * code paths fire their plugins (instead of using document-ready,
2544                  * which can and should be limited to firing only once).
2545                  *
2546                  * Features like navigating to other wiki pages, previewing an edit
2547                  * and editing itself – without a refresh – can then retrigger these
2548                  * hooks accordingly to ensure everything still works as expected.
2549                  *
2550                  * Example usage:
2551                  *
2552                  *     mw.hook( 'wikipage.content' ).add( fn ).remove( fn );
2553                  *     mw.hook( 'wikipage.content' ).fire( $content );
2554                  *
2555                  * Handlers can be added and fired for arbitrary event names at any time. The same
2556                  * event can be fired multiple times. The last run of an event is memorized
2557                  * (similar to `$(document).ready` and `$.Deferred().done`).
2558                  * This means if an event is fired, and a handler added afterwards, the added
2559                  * function will be fired right away with the last given event data.
2560                  *
2561                  * Like Deferreds and Promises, the mw.hook object is both detachable and chainable.
2562                  * Thus allowing flexible use and optimal maintainability and authority control.
2563                  * You can pass around the `add` and/or `fire` method to another piece of code
2564                  * without it having to know the event name (or `mw.hook` for that matter).
2565                  *
2566                  *     var h = mw.hook( 'bar.ready' );
2567                  *     new mw.Foo( .. ).fetch( { callback: h.fire } );
2568                  *
2569                  * Note: Events are documented with an underscore instead of a dot in the event
2570                  * name due to jsduck not supporting dots in that position.
2571                  *
2572                  * @class mw.hook
2573                  */
2574                 hook: ( function () {
2575                         var lists = {};
2576
2577                         /**
2578                          * Create an instance of mw.hook.
2579                          *
2580                          * @method hook
2581                          * @member mw
2582                          * @param {string} name Name of hook.
2583                          * @return {mw.hook}
2584                          */
2585                         return function ( name ) {
2586                                 var list = hasOwn.call( lists, name ) ?
2587                                         lists[ name ] :
2588                                         lists[ name ] = $.Callbacks( 'memory' );
2589
2590                                 return {
2591                                         /**
2592                                          * Register a hook handler
2593                                          *
2594                                          * @param {...Function} handler Function to bind.
2595                                          * @chainable
2596                                          */
2597                                         add: list.add,
2598
2599                                         /**
2600                                          * Unregister a hook handler
2601                                          *
2602                                          * @param {...Function} handler Function to unbind.
2603                                          * @chainable
2604                                          */
2605                                         remove: list.remove,
2606
2607                                         /**
2608                                          * Run a hook.
2609                                          *
2610                                          * @param {...Mixed} data
2611                                          * @chainable
2612                                          */
2613                                         fire: function () {
2614                                                 return list.fireWith.call( this, null, slice.call( arguments ) );
2615                                         }
2616                                 };
2617                         };
2618                 }() )
2619         };
2620
2621         // Alias $j to jQuery for backwards compatibility
2622         // @deprecated since 1.23 Use $ or jQuery instead
2623         mw.log.deprecate( window, '$j', $, 'Use $ or jQuery instead.' );
2624
2625         /**
2626          * Log a message to window.console, if possible.
2627          *
2628          * Useful to force logging of some errors that are otherwise hard to detect (i.e., this logs
2629          * also in production mode). Gets console references in each invocation instead of caching the
2630          * reference, so that debugging tools loaded later are supported (e.g. Firebug Lite in IE).
2631          *
2632          * @private
2633          * @method log_
2634          * @param {string} topic Stream name passed by mw.track
2635          * @param {Object} data Data passed by mw.track
2636          * @param {Error} [data.exception]
2637          * @param {string} data.source Error source
2638          * @param {string} [data.module] Name of module which caused the error
2639          */
2640         function log( topic, data ) {
2641                 var msg,
2642                         e = data.exception,
2643                         source = data.source,
2644                         module = data.module,
2645                         console = window.console;
2646
2647                 if ( console && console.log ) {
2648                         msg = ( e ? 'Exception' : 'Error' ) + ' in ' + source;
2649                         if ( module ) {
2650                                 msg += ' in module ' + module;
2651                         }
2652                         msg += ( e ? ':' : '.' );
2653                         console.log( msg );
2654
2655                         // If we have an exception object, log it to the error channel to trigger
2656                         // proper stacktraces in browsers that support it. No fallback as we have
2657                         // no browsers that don't support error(), but do support log().
2658                         if ( e && console.error ) {
2659                                 console.error( String( e ), e );
2660                         }
2661                 }
2662         }
2663
2664         // Subscribe to error streams
2665         mw.trackSubscribe( 'resourceloader.exception', log );
2666         mw.trackSubscribe( 'resourceloader.assert', log );
2667
2668         /**
2669          * Fired when all modules associated with the page have finished loading.
2670          *
2671          * @event resourceloader_loadEnd
2672          * @member mw.hook
2673          */
2674         $( function () {
2675                 var loading = $.grep( mw.loader.getModuleNames(), function ( module ) {
2676                         return mw.loader.getState( module ) === 'loading';
2677                 } );
2678                 // In order to use jQuery.when (which stops early if one of the promises got rejected)
2679                 // cast any loading failures into successes. We only need a callback, not the module.
2680                 loading = $.map( loading, function ( module ) {
2681                         return mw.loader.using( module ).then( null, function () {
2682                                 return $.Deferred().resolve();
2683                         } );
2684                 } );
2685                 $.when.apply( $, loading ).then( function () {
2686                         mwPerformance.mark( 'mwLoadEnd' );
2687                         mw.hook( 'resourceloader.loadEnd' ).fire();
2688                 } );
2689         } );
2690
2691         // Attach to window and globally alias
2692         window.mw = window.mediaWiki = mw;
2693 }( jQuery ) );