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 += 1 ) {
 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} fmt 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                  * Shorcut 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
 593                         /**
 594                          * @class mw.log
 595                          * @singleton
 596                          */
 597
 598                         /**
 599                          * Write a message the console's warning channel.
 600                          * Actions not supported by the browser console are silently ignored.
 601                          *
 602                          * @param {string...} msg Messages to output to console
 603                          */
 604                         log.warn = function () {
 605                                 var console = window.console;
 606                                 if ( console && console.warn && console.warn.apply ) {
 607                                         console.warn.apply( console, arguments );
 608                                 }
 609                         };
 610
 611                         /**
 612                          * Write a message the console's error channel.
 613                          *
 614                          * Most browsers provide a stacktrace by default if the argument
 615                          * is a caught Error object.
 616                          *
 617                          * @since 1.26
 618                          * @param {Error|string...} msg Messages to output to console
 619                          */
 620                         log.error = function () {
 621                                 var console = window.console;
 622                                 if ( console && console.error && console.error.apply ) {
 623                                         console.error.apply( console, arguments );
 624                                 }
 625                         };
 626
 627                         /**
 628                          * Create a property in a host object that, when accessed, will produce
 629                          * a deprecation warning in the console with backtrace.
 630                          *
 631                          * @param {Object} obj Host object of deprecated property
 632                          * @param {string} key Name of property to create in `obj`
 633                          * @param {Mixed} val The value this property should return when accessed
 634                          * @param {string} [msg] Optional text to include in the deprecation message
 635                          */
 636                         log.deprecate = !Object.defineProperty ? function ( obj, key, val ) {
 637                                 obj[ key ] = val;
 638                         } : function ( obj, key, val, msg ) {
 639                                 msg = 'Use of "' + key + '" is deprecated.' + ( msg ? ( ' ' + msg ) : '' );
 640                                 // Support: IE8
 641                                 // Can throw on Object.defineProperty.
 642                                 try {
 643                                         Object.defineProperty( obj, key, {
 644                                                 configurable: true,
 645                                                 enumerable: true,
 646                                                 get: function () {
 647                                                         mw.track( 'mw.deprecate', key );
 648                                                         mw.log.warn( msg );
 649                                                         return val;
 650                                                 },
 651                                                 set: function ( newVal ) {
 652                                                         mw.track( 'mw.deprecate', key );
 653                                                         mw.log.warn( msg );
 654                                                         val = newVal;
 655                                                 }
 656                                         } );
 657                                 } catch ( err ) {
 658                                         // Fallback to creating a copy of the value to the object.
 659                                         obj[ key ] = val;
 660                                 }
 661                         };
 662
 663                         return log;
 664                 }() ),
 665
 666                 /**
 667                  * Client for ResourceLoader server end point.
 668                  *
 669                  * This client is in charge of maintaining the module registry and state
 670                  * machine, initiating network (batch) requests for loading modules, as
 671                  * well as dependency resolution and execution of source code.
 672                  *
 673                  * For more information, refer to
 674                  * <https://www.mediawiki.org/wiki/ResourceLoader/Features>
 675                  *
 676                  * @class mw.loader
 677                  * @singleton
 678                  */
 679                 loader: ( function () {
 680
 681                         /**
 682                          * Fired via mw.track on various resource loading errors.
 683                          *
 684                          * @event resourceloader_exception
 685                          * @param {Error|Mixed} e The error that was thrown. Almost always an Error
 686                          *   object, but in theory module code could manually throw something else, and that
 687                          *   might also end up here.
 688                          * @param {string} [module] Name of the module which caused the error. Omitted if the
 689                          *   error is not module-related or the module cannot be easily identified due to
 690                          *   batched handling.
 691                          * @param {string} source Source of the error. Possible values:
 692                          *
 693                          *   - style: stylesheet error (only affects old IE where a special style loading method
 694                          *     is used)
 695                          *   - load-callback: exception thrown by user callback
 696                          *   - module-execute: exception thrown by module code
 697                          *   - store-eval: could not evaluate module code cached in localStorage
 698                          *   - store-localstorage-init: localStorage or JSON parse error in mw.loader.store.init
 699                          *   - store-localstorage-json: JSON conversion error in mw.loader.store.set
 700                          *   - store-localstorage-update: localStorage or JSON conversion error in mw.loader.store.update
 701                          */
 702
 703                         /**
 704                          * Fired via mw.track on resource loading error conditions.
 705                          *
 706                          * @event resourceloader_assert
 707                          * @param {string} source Source of the error. Possible values:
 708                          *
 709                          *   - bug-T59567: failed to cache script due to an Opera function -> string conversion
 710                          *     bug; see <https://phabricator.wikimedia.org/T59567> for details
 711                          */
 712
 713                         /**
 714                          * Mapping of registered modules.
 715                          *
 716                          * See #implement and #execute for exact details on support for script, style and messages.
 717                          *
 718                          * Format:
 719                          *
 720                          *     {
 721                          *         'moduleName': {
 722                          *             // From mw.loader.register()
 723                          *             'version': '########' (hash)
 724                          *             'dependencies': ['required.foo', 'bar.also', ...], (or) function () {}
 725                          *             'group': 'somegroup', (or) null
 726                          *             'source': 'local', (or) 'anotherwiki'
 727                          *             'skip': 'return !!window.Example', (or) null
 728                          *
 729                          *             // Set from execute() or mw.loader.state()
 730                          *             'state': 'registered', 'loaded', 'loading', 'ready', 'error', or 'missing'
 731                          *
 732                          *             // Optionally added at run-time by mw.loader.implement()
 733                          *             'skipped': true
 734                          *             'script': closure, array of urls, or string
 735                          *             'style': { ... } (see #execute)
 736                          *             'messages': { 'key': 'value', ... }
 737                          *         }
 738                          *     }
 739                          *
 740                          * State machine:
 741                          *
 742                          * - `registered`:
 743                          *    The module is known to the system but not yet requested.
 744                          *    Meta data is registered via mw.loader#register. Calls to that method are
 745                          *    generated server-side by the startup module.
 746                          * - `loading` (1):
 747                          *    The module is requested through mw.loader (either directly or as dependency of
 748                          *    another module). The client will be fetching module contents from the server.
 749                          *    The contents are then stashed in the registry via mw.loader#implement.
 750                          * - `loaded`:
 751                          *    The module has been requested from the server and stashed via mw.loader#implement.
 752                          *    If the module has no more dependencies in-fight, the module will be executed
 753                          *    right away. Otherwise execution is deferred, controlled via #handlePending.
 754                          * - `loading` (2):
 755                          *    The module is being executed.
 756                          *    TODO: Create a new state instead of re-using the "loading" state.
 757                          * - `ready`:
 758                          *    The module has been successfully executed.
 759                          * - `error`:
 760                          *    The module (or one of its dependencies) produced an error during execution.
 761                          * - `missing`:
 762                          *    The module was registered client-side and requested, but the server denied knowledge
 763                          *    of the module's existence.
 764                          *
 765                          * @property
 766                          * @private
 767                          */
 768                         var registry = {},
 769                                 // Mapping of sources, keyed by source-id, values are strings.
 770                                 //
 771                                 // Format:
 772                                 //
 773                                 //     {
 774                                 //         'sourceId': 'http://example.org/w/load.php'
 775                                 //     }
 776                                 //
 777                                 sources = {},
 778
 779                                 // List of modules which will be loaded as when ready
 780                                 batch = [],
 781
 782                                 // List of modules to be loaded
 783                                 queue = [],
 784
 785                                 // List of callback functions waiting for modules to be ready to be called
 786                                 jobs = [],
 787
 788                                 // Selector cache for the marker element. Use getMarker() to get/use the marker!
 789                                 $marker = null,
 790
 791                                 // Buffer for #addEmbeddedCSS
 792                                 cssBuffer = '',
 793
 794                                 // Callbacks for #addEmbeddedCSS
 795                                 cssCallbacks = $.Callbacks();
 796
 797                         function getMarker() {
 798                                 if ( !$marker ) {
 799                                         // Cache
 800                                         $marker = $( 'meta[name="ResourceLoaderDynamicStyles"]' );
 801                                         if ( !$marker.length ) {
 802                                                 mw.log( 'No <meta name="ResourceLoaderDynamicStyles"> found, inserting dynamically' );
 803                                                 $marker = $( '<meta>' ).attr( 'name', 'ResourceLoaderDynamicStyles' ).appendTo( 'head' );
 804                                         }
 805                                 }
 806                                 return $marker;
 807                         }
 808
 809                         /**
 810                          * Create a new style element and add it to the DOM.
 811                          *
 812                          * @private
 813                          * @param {string} text CSS text
 814                          * @param {HTMLElement|jQuery} [nextnode=document.head] The element where the style tag
 815                          *  should be inserted before
 816                          * @return {HTMLElement} Reference to the created style element
 817                          */
 818                         function newStyleTag( text, nextnode ) {
 819                                 var s = document.createElement( 'style' );
 820                                 // Support: IE
 821                                 // Must attach to document before setting cssText (bug 33305)
 822                                 if ( nextnode ) {
 823                                         $( nextnode ).before( s );
 824                                 } else {
 825                                         document.getElementsByTagName( 'head' )[ 0 ].appendChild( s );
 826                                 }
 827                                 if ( s.styleSheet ) {
 828                                         // Support: IE6-10
 829                                         // Old IE ignores appended text nodes, access stylesheet directly.
 830                                         s.styleSheet.cssText = text;
 831                                 } else {
 832                                         // Standard behaviour
 833                                         s.appendChild( document.createTextNode( text ) );
 834                                 }
 835                                 return s;
 836                         }
 837
 838                         /**
 839                          * Add a bit of CSS text to the current browser page.
 840                          *
 841                          * The CSS will be appended to an existing ResourceLoader-created `<style>` tag
 842                          * or create a new one based on whether the given `cssText` is safe for extension.
 843                          *
 844                          * @param {string} [cssText=cssBuffer] If called without cssText,
 845                          *  the internal buffer will be inserted instead.
 846                          * @param {Function} [callback]
 847                          */
 848                         function addEmbeddedCSS( cssText, callback ) {
 849                                 var $style, styleEl;
 850
 851                                 function fireCallbacks() {
 852                                         var oldCallbacks = cssCallbacks;
 853                                         // Reset cssCallbacks variable so it's not polluted by any calls to
 854                                         // addEmbeddedCSS() from one of the callbacks (T105973)
 855                                         cssCallbacks = $.Callbacks();
 856                                         oldCallbacks.fire().empty();
 857                                 }
 858
 859                                 if ( callback ) {
 860                                         cssCallbacks.add( callback );
 861                                 }
 862
 863                                 // Yield once before inserting the <style> tag. There are likely
 864                                 // more calls coming up which we can combine this way.
 865                                 // Appending a stylesheet and waiting for the browser to repaint
 866                                 // is fairly expensive, this reduces that (bug 45810)
 867                                 if ( cssText ) {
 868                                         // Be careful not to extend the buffer with css that needs a new stylesheet.
 869                                         // cssText containing `@import` rules needs to go at the start of a buffer,
 870                                         // since those only work when placed at the start of a stylesheet; bug 35562.
 871                                         if ( !cssBuffer || cssText.slice( 0, '@import'.length ) !== '@import' ) {
 872                                                 // Linebreak for somewhat distinguishable sections
 873                                                 // (the rl-cachekey comment separating each)
 874                                                 cssBuffer += '\n' + cssText;
 875                                                 // TODO: Use requestAnimationFrame in the future which will
 876                                                 // perform even better by not injecting styles while the browser
 877                                                 // is painting.
 878                                                 setTimeout( function () {
 879                                                         // Can't pass addEmbeddedCSS to setTimeout directly because Firefox
 880                                                         // (below version 13) has the non-standard behaviour of passing a
 881                                                         // numerical "lateness" value as first argument to this callback
 882                                                         // http://benalman.com/news/2009/07/the-mysterious-firefox-settime/
 883                                                         addEmbeddedCSS();
 884                                                 } );
 885                                                 return;
 886                                         }
 887
 888                                 // This is a delayed call and we got a buffer still
 889                                 } else if ( cssBuffer ) {
 890                                         cssText = cssBuffer;
 891                                         cssBuffer = '';
 892
 893                                 } else {
 894                                         // This is a delayed call, but buffer was already cleared by
 895                                         // another delayed call.
 896                                         return;
 897                                 }
 898
 899                                 // By default, always create a new <style>. Appending text to a <style>
 900                                 // tag is bad as it means the contents have to be re-parsed (bug 45810).
 901                                 //
 902                                 // Except, of course, in IE 9 and below. In there we default to re-using and
 903                                 // appending to a <style> tag due to the IE stylesheet limit (bug 31676).
 904                                 if ( 'documentMode' in document && document.documentMode <= 9 ) {
 905
 906                                         $style = getMarker().prev();
 907                                         // Verify that the element before the marker actually is a
 908                                         // <style> tag and one that came from ResourceLoader
 909                                         // (not some other style tag or even a `<meta>` or `<script>`).
 910                                         if ( $style.data( 'ResourceLoaderDynamicStyleTag' ) === true ) {
 911                                                 // There's already a dynamic <style> tag present and
 912                                                 // we are able to append more to it.
 913                                                 styleEl = $style.get( 0 );
 914                                                 // Support: IE6-10
 915                                                 if ( styleEl.styleSheet ) {
 916                                                         try {
 917                                                                 styleEl.styleSheet.cssText += cssText;
 918                                                         } catch ( e ) {
 919                                                                 mw.track( 'resourceloader.exception', { exception: e, source: 'stylesheet' } );
 920                                                         }
 921                                                 } else {
 922                                                         styleEl.appendChild( document.createTextNode( cssText ) );
 923                                                 }
 924                                                 fireCallbacks();
 925                                                 return;
 926                                         }
 927                                 }
 928
 929                                 $( newStyleTag( cssText, getMarker() ) ).data( 'ResourceLoaderDynamicStyleTag', true );
 930
 931                                 fireCallbacks();
 932                         }
 933
 934                         /**
 935                          * @since 1.26
 936                          * @param {Array} modules List of module names
 937                          * @return {string} Hash of concatenated version hashes.
 938                          */
 939                         function getCombinedVersion( modules ) {
 940                                 var hashes = $.map( modules, function ( module ) {
 941                                         return registry[ module ].version;
 942                                 } );
 943                                 // Trim for consistency with server-side ResourceLoader::makeHash. It also helps
 944                                 // save precious space in the limited query string. Otherwise modules are more
 945                                 // likely to require multiple HTTP requests.
 946                                 return sha1( hashes.join( '' ) ).slice( 0, 12 );
 947                         }
 948
 949                         /**
 950                          * Determine whether all dependencies are in state 'ready', which means we may
 951                          * execute the module or job now.
 952                          *
 953                          * @private
 954                          * @param {Array} module Names of modules to be checked
 955                          * @return {boolean} True if all modules are in state 'ready', false otherwise
 956                          */
 957                         function allReady( modules ) {
 958                                 var i;
 959                                 for ( i = 0; i < modules.length; i++ ) {
 960                                         if ( mw.loader.getState( modules[ i ] ) !== 'ready' ) {
 961                                                 return false;
 962                                         }
 963                                 }
 964                                 return true;
 965                         }
 966
 967                         /**
 968                          * Determine whether all dependencies are in state 'ready', which means we may
 969                          * execute the module or job now.
 970                          *
 971                          * @private
 972                          * @param {Array} modules Names of modules to be checked
 973                          * @return {boolean} True if no modules are in state 'error' or 'missing', false otherwise
 974                          */
 975                         function anyFailed( modules ) {
 976                                 var i, state;
 977                                 for ( i = 0; i < modules.length; i++ ) {
 978                                         state = mw.loader.getState( modules[ i ] );
 979                                         if ( state === 'error' || state === 'missing' ) {
 980                                                 return true;
 981                                         }
 982                                 }
 983                                 return false;
 984                         }
 985
 986                         /**
 987                          * A module has entered state 'ready', 'error', or 'missing'. Automatically update
 988                          * pending jobs and modules that depend upon this module. If the given module failed,
 989                          * propagate the 'error' state up the dependency tree. Otherwise, go ahead an execute
 990                          * all jobs/modules now having their dependencies satisfied.
 991                          *
 992                          * Jobs that depend on a failed module, will have their error callback ran (if any).
 993                          *
 994                          * @private
 995                          * @param {string} module Name of module that entered one of the states 'ready', 'error', or 'missing'.
 996                          */
 997                         function handlePending( module ) {
 998                                 var j, job, hasErrors, m, stateChange;
 999
1000                                 if ( registry[ module ].state === 'error' || registry[ module ].state === 'missing' ) {
1001                                         // If the current module failed, mark all dependent modules also as failed.
1002                                         // Iterate until steady-state to propagate the error state upwards in the
1003                                         // dependency tree.
1004                                         do {
1005                                                 stateChange = false;
1006                                                 for ( m in registry ) {
1007                                                         if ( registry[ m ].state !== 'error' && registry[ m ].state !== 'missing' ) {
1008                                                                 if ( anyFailed( registry[ m ].dependencies ) ) {
1009                                                                         registry[ m ].state = 'error';
1010                                                                         stateChange = true;
1011                                                                 }
1012                                                         }
1013                                                 }
1014                                         } while ( stateChange );
1015                                 }
1016
1017                                 // Execute all jobs whose dependencies are either all satisfied or contain at least one failed module.
1018                                 for ( j = 0; j < jobs.length; j += 1 ) {
1019                                         hasErrors = anyFailed( jobs[ j ].dependencies );
1020                                         if ( hasErrors || allReady( jobs[ j ].dependencies ) ) {
1021                                                 // All dependencies satisfied, or some have errors
1022                                                 job = jobs[ j ];
1023                                                 jobs.splice( j, 1 );
1024                                                 j -= 1;
1025                                                 try {
1026                                                         if ( hasErrors ) {
1027                                                                 if ( $.isFunction( job.error ) ) {
1028                                                                         job.error( new Error( 'Module ' + module + ' has failed dependencies' ), [ module ] );
1029                                                                 }
1030                                                         } else {
1031                                                                 if ( $.isFunction( job.ready ) ) {
1032                                                                         job.ready();
1033                                                                 }
1034                                                         }
1035                                                 } catch ( e ) {
1036                                                         // A user-defined callback raised an exception.
1037                                                         // Swallow it to protect our state machine!
1038                                                         mw.track( 'resourceloader.exception', { exception: e, module: module, source: 'load-callback' } );
1039                                                 }
1040                                         }
1041                                 }
1042
1043                                 if ( registry[ module ].state === 'ready' ) {
1044                                         // The current module became 'ready'. Set it in the module store, and recursively execute all
1045                                         // dependent modules that are loaded and now have all dependencies satisfied.
1046                                         mw.loader.store.set( module, registry[ module ] );
1047                                         for ( m in registry ) {
1048                                                 if ( registry[ m ].state === 'loaded' && allReady( registry[ m ].dependencies ) ) {
1049                                                         execute( m );
1050                                                 }
1051                                         }
1052                                 }
1053                         }
1054
1055                         /**
1056                          * Resolve dependencies and detect circular references.
1057                          *
1058                          * @private
1059                          * @param {string} module Name of the top-level module whose dependencies shall be
1060                          *  resolved and sorted.
1061                          * @param {Array} resolved Returns a topological sort of the given module and its
1062                          *  dependencies, such that later modules depend on earlier modules. The array
1063                          *  contains the module names. If the array contains already some module names,
1064                          *  this function appends its result to the pre-existing array.
1065                          * @param {Object} [unresolved] Hash used to track the current dependency
1066                          *  chain; used to report loops in the dependency graph.
1067                          * @throws {Error} If any unregistered module or a dependency loop is encountered
1068                          */
1069                         function sortDependencies( module, resolved, unresolved ) {
1070                                 var n, deps, len, skip;
1071
1072                                 if ( !hasOwn.call( registry, module ) ) {
1073                                         throw new Error( 'Unknown dependency: ' + module );
1074                                 }
1075
1076                                 if ( registry[ module ].skip !== null ) {
1077                                         /*jshint evil:true */
1078                                         skip = new Function( registry[ module ].skip );
1079                                         registry[ module ].skip = null;
1080                                         if ( skip() ) {
1081                                                 registry[ module ].skipped = true;
1082                                                 registry[ module ].dependencies = [];
1083                                                 registry[ module ].state = 'ready';
1084                                                 handlePending( module );
1085                                                 return;
1086                                         }
1087                                 }
1088
1089                                 // Resolves dynamic loader function and replaces it with its own results
1090                                 if ( $.isFunction( registry[ module ].dependencies ) ) {
1091                                         registry[ module ].dependencies = registry[ module ].dependencies();
1092                                         // Ensures the module's dependencies are always in an array
1093                                         if ( typeof registry[ module ].dependencies !== 'object' ) {
1094                                                 registry[ module ].dependencies = [ registry[ module ].dependencies ];
1095                                         }
1096                                 }
1097                                 if ( $.inArray( module, resolved ) !== -1 ) {
1098                                         // Module already resolved; nothing to do
1099                                         return;
1100                                 }
1101                                 // Create unresolved if not passed in
1102                                 if ( !unresolved ) {
1103                                         unresolved = {};
1104                                 }
1105                                 // Tracks down dependencies
1106                                 deps = registry[ module ].dependencies;
1107                                 len = deps.length;
1108                                 for ( n = 0; n < len; n += 1 ) {
1109                                         if ( $.inArray( deps[ n ], resolved ) === -1 ) {
1110                                                 if ( unresolved[ deps[ n ] ] ) {
1111                                                         throw new Error(
1112                                                                 'Circular reference detected: ' + module +
1113                                                                 ' -> ' + deps[ n ]
1114                                                         );
1115                                                 }
1116
1117                                                 // Add to unresolved
1118                                                 unresolved[ module ] = true;
1119                                                 sortDependencies( deps[ n ], resolved, unresolved );
1120                                                 delete unresolved[ module ];
1121                                         }
1122                                 }
1123                                 resolved[ resolved.length ] = module;
1124                         }
1125
1126                         /**
1127                          * Get a list of module names that a module depends on in their proper dependency
1128                          * order.
1129                          *
1130                          * @private
1131                          * @param {string[]} module Array of string module names
1132                          * @return {Array} List of dependencies, including 'module'.
1133                          */
1134                         function resolve( modules ) {
1135                                 var resolved = [];
1136                                 $.each( modules, function ( idx, module ) {
1137                                         sortDependencies( module, resolved );
1138                                 } );
1139                                 return resolved;
1140                         }
1141
1142                         /**
1143                          * Load and execute a script with callback.
1144                          *
1145                          * @private
1146                          * @param {string} src URL to script, will be used as the src attribute in the script tag
1147                          * @param {Function} [callback] Callback which will be run when the script is done
1148                          */
1149                         function addScript( src, callback ) {
1150                                 $.ajax( {
1151                                         url: src,
1152                                         dataType: 'script',
1153                                         // Force jQuery behaviour to be for crossDomain. Otherwise jQuery would use
1154                                         // XHR for a same domain request instead of <script>, which changes the request
1155                                         // headers (potentially missing a cache hit), and reduces caching in general
1156                                         // since browsers cache XHR much less (if at all). And XHR means we retreive
1157                                         // text, so we'd need to $.globalEval, which then messes up line numbers.
1158                                         crossDomain: true,
1159                                         cache: true
1160                                 } ).always( callback );
1161                         }
1162
1163                         /**
1164                          * Executes a loaded module, making it ready to use
1165                          *
1166                          * @private
1167                          * @param {string} module Module name to execute
1168                          */
1169                         function execute( module ) {
1170                                 var key, value, media, i, urls, cssHandle, checkCssHandles, runScript,
1171                                         cssHandlesRegistered = false;
1172
1173                                 if ( !hasOwn.call( registry, module ) ) {
1174                                         throw new Error( 'Module has not been registered yet: ' + module );
1175                                 }
1176                                 if ( registry[ module ].state === 'registered' ) {
1177                                         throw new Error( 'Module has not been requested from the server yet: ' + module );
1178                                 }
1179                                 if ( registry[ module ].state === 'loading' ) {
1180                                         throw new Error( 'Module has not completed loading yet: ' + module );
1181                                 }
1182                                 if ( registry[ module ].state === 'ready' ) {
1183                                         throw new Error( 'Module has already been executed: ' + module );
1184                                 }
1185
1186                                 /**
1187                                  * Define loop-function here for efficiency
1188                                  * and to avoid re-using badly scoped variables.
1189                                  *
1190                                  * @ignore
1191                                  */
1192                                 function addLink( media, url ) {
1193                                         var el = document.createElement( 'link' );
1194                                         // Support: IE
1195                                         // Insert in document *before* setting href
1196                                         getMarker().before( el );
1197                                         el.rel = 'stylesheet';
1198                                         if ( media && media !== 'all' ) {
1199                                                 el.media = media;
1200                                         }
1201                                         // If you end up here from an IE exception "SCRIPT: Invalid property value.",
1202                                         // see #addEmbeddedCSS, bug 31676, and bug 47277 for details.
1203                                         el.href = url;
1204                                 }
1205
1206                                 runScript = function () {
1207                                         var script, markModuleReady, nestedAddScript, legacyWait,
1208                                                 // Expand to include dependencies since we have to exclude both legacy modules
1209                                                 // and their dependencies from the legacyWait (to prevent a circular dependency).
1210                                                 legacyModules = resolve( mw.config.get( 'wgResourceLoaderLegacyModules', [] ) );
1211                                         try {
1212                                                 script = registry[ module ].script;
1213                                                 markModuleReady = function () {
1214                                                         registry[ module ].state = 'ready';
1215                                                         handlePending( module );
1216                                                 };
1217                                                 nestedAddScript = function ( arr, callback, i ) {
1218                                                         // Recursively call addScript() in its own callback
1219                                                         // for each element of arr.
1220                                                         if ( i >= arr.length ) {
1221                                                                 // We're at the end of the array
1222                                                                 callback();
1223                                                                 return;
1224                                                         }
1225
1226                                                         addScript( arr[ i ], function () {
1227                                                                 nestedAddScript( arr, callback, i + 1 );
1228                                                         } );
1229                                                 };
1230
1231                                                 legacyWait = ( $.inArray( module, legacyModules ) !== -1 )
1232                                                         ? $.Deferred().resolve()
1233                                                         : mw.loader.using( legacyModules );
1234
1235                                                 legacyWait.always( function () {
1236                                                         if ( $.isArray( script ) ) {
1237                                                                 nestedAddScript( script, markModuleReady, 0 );
1238                                                         } else if ( $.isFunction( script ) ) {
1239                                                                 // Pass jQuery twice so that the signature of the closure which wraps
1240                                                                 // the script can bind both '$' and 'jQuery'.
1241                                                                 script( $, $ );
1242                                                                 markModuleReady();
1243                                                         } else if ( typeof script === 'string' ) {
1244                                                                 // Site and user modules are a legacy scripts that run in the global scope.
1245                                                                 // This is transported as a string instead of a function to avoid needing
1246                                                                 // to use string manipulation to undo the function wrapper.
1247                                                                 if ( module === 'user' ) {
1248                                                                         // Implicit dependency on the site module. Not real dependency because
1249                                                                         // it should run after 'site' regardless of whether it succeeds or fails.
1250                                                                         mw.loader.using( 'site' ).always( function () {
1251                                                                                 $.globalEval( script );
1252                                                                                 markModuleReady();
1253                                                                         } );
1254                                                                 } else {
1255                                                                         $.globalEval( script );
1256                                                                         markModuleReady();
1257                                                                 }
1258                                                         }
1259                                                 } );
1260                                         } catch ( e ) {
1261                                                 // This needs to NOT use mw.log because these errors are common in production mode
1262                                                 // and not in debug mode, such as when a symbol that should be global isn't exported
1263                                                 registry[ module ].state = 'error';
1264                                                 mw.track( 'resourceloader.exception', { exception: e, module: module, source: 'module-execute' } );
1265                                                 handlePending( module );
1266                                         }
1267                                 };
1268
1269                                 // This used to be inside runScript, but since that is now fired asychronously
1270                                 // (after CSS is loaded) we need to set it here right away. It is crucial that
1271                                 // when execute() is called this is set synchronously, otherwise modules will get
1272                                 // executed multiple times as the registry will state that it isn't loading yet.
1273                                 registry[ module ].state = 'loading';
1274
1275                                 // Add localizations to message system
1276                                 if ( registry[ module ].messages ) {
1277                                         mw.messages.set( registry[ module ].messages );
1278                                 }
1279
1280                                 // Initialise templates
1281                                 if ( registry[ module ].templates ) {
1282                                         mw.templates.set( module, registry[ module ].templates );
1283                                 }
1284
1285                                 // Make sure we don't run the scripts until all stylesheet insertions have completed.
1286                                 ( function () {
1287                                         var pending = 0;
1288                                         checkCssHandles = function () {
1289                                                 // cssHandlesRegistered ensures we don't take off too soon, e.g. when
1290                                                 // one of the cssHandles is fired while we're still creating more handles.
1291                                                 if ( cssHandlesRegistered && pending === 0 && runScript ) {
1292                                                         runScript();
1293                                                         runScript = undefined; // Revoke
1294                                                 }
1295                                         };
1296                                         cssHandle = function () {
1297                                                 var check = checkCssHandles;
1298                                                 pending++;
1299                                                 return function () {
1300                                                         if ( check ) {
1301                                                                 pending--;
1302                                                                 check();
1303                                                                 check = undefined; // Revoke
1304                                                         }
1305                                                 };
1306                                         };
1307                                 }() );
1308
1309                                 // Process styles (see also mw.loader.implement)
1310                                 // * back-compat: { <media>: css }
1311                                 // * back-compat: { <media>: [url, ..] }
1312                                 // * { "css": [css, ..] }
1313                                 // * { "url": { <media>: [url, ..] } }
1314                                 if ( registry[ module ].style ) {
1315                                         for ( key in registry[ module ].style ) {
1316                                                 value = registry[ module ].style[ key ];
1317                                                 media = undefined;
1318
1319                                                 if ( key !== 'url' && key !== 'css' ) {
1320                                                         // Backwards compatibility, key is a media-type
1321                                                         if ( typeof value === 'string' ) {
1322                                                                 // back-compat: { <media>: css }
1323                                                                 // Ignore 'media' because it isn't supported (nor was it used).
1324                                                                 // Strings are pre-wrapped in "@media". The media-type was just ""
1325                                                                 // (because it had to be set to something).
1326                                                                 // This is one of the reasons why this format is no longer used.
1327                                                                 addEmbeddedCSS( value, cssHandle() );
1328                                                         } else {
1329                                                                 // back-compat: { <media>: [url, ..] }
1330                                                                 media = key;
1331                                                                 key = 'bc-url';
1332                                                         }
1333                                                 }
1334
1335                                                 // Array of css strings in key 'css',
1336                                                 // or back-compat array of urls from media-type
1337                                                 if ( $.isArray( value ) ) {
1338                                                         for ( i = 0; i < value.length; i += 1 ) {
1339                                                                 if ( key === 'bc-url' ) {
1340                                                                         // back-compat: { <media>: [url, ..] }
1341                                                                         addLink( media, value[ i ] );
1342                                                                 } else if ( key === 'css' ) {
1343                                                                         // { "css": [css, ..] }
1344                                                                         addEmbeddedCSS( value[ i ], cssHandle() );
1345                                                                 }
1346                                                         }
1347                                                 // Not an array, but a regular object
1348                                                 // Array of urls inside media-type key
1349                                                 } else if ( typeof value === 'object' ) {
1350                                                         // { "url": { <media>: [url, ..] } }
1351                                                         for ( media in value ) {
1352                                                                 urls = value[ media ];
1353                                                                 for ( i = 0; i < urls.length; i += 1 ) {
1354                                                                         addLink( media, urls[ i ] );
1355                                                                 }
1356                                                         }
1357                                                 }
1358                                         }
1359                                 }
1360
1361                                 // Kick off.
1362                                 cssHandlesRegistered = true;
1363                                 checkCssHandles();
1364                         }
1365
1366                         /**
1367                          * Adds a dependencies to the queue with optional callbacks to be run
1368                          * when the dependencies are ready or fail
1369                          *
1370                          * @private
1371                          * @param {string|string[]} dependencies Module name or array of string module names
1372                          * @param {Function} [ready] Callback to execute when all dependencies are ready
1373                          * @param {Function} [error] Callback to execute when any dependency fails
1374                          */
1375                         function request( dependencies, ready, error ) {
1376                                 // Allow calling by single module name
1377                                 if ( typeof dependencies === 'string' ) {
1378                                         dependencies = [ dependencies ];
1379                                 }
1380
1381                                 // Add ready and error callbacks if they were given
1382                                 if ( ready !== undefined || error !== undefined ) {
1383                                         jobs[ jobs.length ] = {
1384                                                 dependencies: $.grep( dependencies, function ( module ) {
1385                                                         var state = mw.loader.getState( module );
1386                                                         return state === 'registered' || state === 'loaded' || state === 'loading';
1387                                                 } ),
1388                                                 ready: ready,
1389                                                 error: error
1390                                         };
1391                                 }
1392
1393                                 $.each( dependencies, function ( idx, module ) {
1394                                         var state = mw.loader.getState( module );
1395                                         // Only queue modules that are still in the initial 'registered' state
1396                                         // (not ones already loading, ready or error).
1397                                         if ( state === 'registered' && $.inArray( module, queue ) === -1 ) {
1398                                                 // Private modules must be embedded in the page. Don't bother queuing
1399                                                 // these as the server will deny them anyway (T101806).
1400                                                 if ( registry[ module ].group === 'private' ) {
1401                                                         registry[ module ].state = 'error';
1402                                                         handlePending( module );
1403                                                         return;
1404                                                 }
1405                                                 queue.push( module );
1406                                         }
1407                                 } );
1408
1409                                 mw.loader.work();
1410                         }
1411
1412                         function sortQuery( o ) {
1413                                 var key,
1414                                         sorted = {},
1415                                         a = [];
1416
1417                                 for ( key in o ) {
1418                                         if ( hasOwn.call( o, key ) ) {
1419                                                 a.push( key );
1420                                         }
1421                                 }
1422                                 a.sort();
1423                                 for ( key = 0; key < a.length; key += 1 ) {
1424                                         sorted[ a[ key ] ] = o[ a[ key ] ];
1425                                 }
1426                                 return sorted;
1427                         }
1428
1429                         /**
1430                          * Converts a module map of the form { foo: [ 'bar', 'baz' ], bar: [ 'baz, 'quux' ] }
1431                          * to a query string of the form foo.bar,baz|bar.baz,quux
1432                          *
1433                          * @private
1434                          */
1435                         function buildModulesString( moduleMap ) {
1436                                 var p, prefix,
1437                                         arr = [];
1438
1439                                 for ( prefix in moduleMap ) {
1440                                         p = prefix === '' ? '' : prefix + '.';
1441                                         arr.push( p + moduleMap[ prefix ].join( ',' ) );
1442                                 }
1443                                 return arr.join( '|' );
1444                         }
1445
1446                         /**
1447                          * Load modules from load.php
1448                          *
1449                          * @private
1450                          * @param {Object} moduleMap Module map, see #buildModulesString
1451                          * @param {Object} currReqBase Object with other parameters (other than 'modules') to use in the request
1452                          * @param {string} sourceLoadScript URL of load.php
1453                          */
1454                         function doRequest( moduleMap, currReqBase, sourceLoadScript ) {
1455                                 var request = $.extend(
1456                                         { modules: buildModulesString( moduleMap ) },
1457                                         currReqBase
1458                                 );
1459                                 request = sortQuery( request );
1460                                 addScript( sourceLoadScript + '?' + $.param( request ) );
1461                         }
1462
1463                         /**
1464                          * Resolve indexed dependencies.
1465                          *
1466                          * ResourceLoader uses an optimization to save space which replaces module names in
1467                          * dependency lists with the index of that module within the array of module
1468                          * registration data if it exists. The benefit is a significant reduction in the data
1469                          * size of the startup module. This function changes those dependency lists back to
1470                          * arrays of strings.
1471                          *
1472                          * @param {Array} modules Modules array
1473                          */
1474                         function resolveIndexedDependencies( modules ) {
1475                                 $.each( modules, function ( idx, module ) {
1476                                         if ( module[ 2 ] ) {
1477                                                 module[ 2 ] = $.map( module[ 2 ], function ( dep ) {
1478                                                         return typeof dep === 'number' ? modules[ dep ][ 0 ] : dep;
1479                                                 } );
1480                                         }
1481                                 } );
1482                         }
1483
1484                         /* Public Members */
1485                         return {
1486                                 /**
1487                                  * The module registry is exposed as an aid for debugging and inspecting page
1488                                  * state; it is not a public interface for modifying the registry.
1489                                  *
1490                                  * @see #registry
1491                                  * @property
1492                                  * @private
1493                                  */
1494                                 moduleRegistry: registry,
1495
1496                                 /**
1497                                  * @inheritdoc #newStyleTag
1498                                  * @method
1499                                  */
1500                                 addStyleTag: newStyleTag,
1501
1502                                 /**
1503                                  * Batch-request queued dependencies from the server.
1504                                  */
1505                                 work: function () {
1506                                         var     reqBase, splits, maxQueryLength, q, b, bSource, bGroup, bSourceGroup,
1507                                                 source, concatSource, origBatch, group, i, modules, sourceLoadScript,
1508                                                 currReqBase, currReqBaseLength, moduleMap, l,
1509                                                 lastDotIndex, prefix, suffix, bytesAdded;
1510
1511                                         // Build a list of request parameters common to all requests.
1512                                         reqBase = {
1513                                                 skin: mw.config.get( 'skin' ),
1514                                                 lang: mw.config.get( 'wgUserLanguage' ),
1515                                                 debug: mw.config.get( 'debug' )
1516                                         };
1517                                         // Split module batch by source and by group.
1518                                         splits = {};
1519                                         maxQueryLength = mw.config.get( 'wgResourceLoaderMaxQueryLength', 2000 );
1520
1521                                         // Appends a list of modules from the queue to the batch
1522                                         for ( q = 0; q < queue.length; q += 1 ) {
1523                                                 // Only request modules which are registered
1524                                                 if ( hasOwn.call( registry, queue[ q ] ) && registry[ queue[ q ] ].state === 'registered' ) {
1525                                                         // Prevent duplicate entries
1526                                                         if ( $.inArray( queue[ q ], batch ) === -1 ) {
1527                                                                 batch[ batch.length ] = queue[ q ];
1528                                                                 // Mark registered modules as loading
1529                                                                 registry[ queue[ q ] ].state = 'loading';
1530                                                         }
1531                                                 }
1532                                         }
1533
1534                                         mw.loader.store.init();
1535                                         if ( mw.loader.store.enabled ) {
1536                                                 concatSource = [];
1537                                                 origBatch = batch;
1538                                                 batch = $.grep( batch, function ( module ) {
1539                                                         var source = mw.loader.store.get( module );
1540                                                         if ( source ) {
1541                                                                 concatSource.push( source );
1542                                                                 return false;
1543                                                         }
1544                                                         return true;
1545                                                 } );
1546                                                 try {
1547                                                         $.globalEval( concatSource.join( ';' ) );
1548                                                 } catch ( err ) {
1549                                                         // Not good, the cached mw.loader.implement calls failed! This should
1550                                                         // never happen, barring ResourceLoader bugs, browser bugs and PEBKACs.
1551                                                         // Depending on how corrupt the string is, it is likely that some
1552                                                         // modules' implement() succeeded while the ones after the error will
1553                                                         // never run and leave their modules in the 'loading' state forever.
1554
1555                                                         // Since this is an error not caused by an individual module but by
1556                                                         // something that infected the implement call itself, don't take any
1557                                                         // risks and clear everything in this cache.
1558                                                         mw.loader.store.clear();
1559                                                         // Re-add the ones still pending back to the batch and let the server
1560                                                         // repopulate these modules to the cache.
1561                                                         // This means that at most one module will be useless (the one that had
1562                                                         // the error) instead of all of them.
1563                                                         mw.track( 'resourceloader.exception', { exception: err, source: 'store-eval' } );
1564                                                         origBatch = $.grep( origBatch, function ( module ) {
1565                                                                 return registry[ module ].state === 'loading';
1566                                                         } );
1567                                                         batch = batch.concat( origBatch );
1568                                                 }
1569                                         }
1570
1571                                         // Early exit if there's nothing to load...
1572                                         if ( !batch.length ) {
1573                                                 return;
1574                                         }
1575
1576                                         // The queue has been processed into the batch, clear up the queue.
1577                                         queue = [];
1578
1579                                         // Always order modules alphabetically to help reduce cache
1580                                         // misses for otherwise identical content.
1581                                         batch.sort();
1582
1583                                         // Split batch by source and by group.
1584                                         for ( b = 0; b < batch.length; b += 1 ) {
1585                                                 bSource = registry[ batch[ b ] ].source;
1586                                                 bGroup = registry[ batch[ b ] ].group;
1587                                                 if ( !hasOwn.call( splits, bSource ) ) {
1588                                                         splits[ bSource ] = {};
1589                                                 }
1590                                                 if ( !hasOwn.call( splits[ bSource ], bGroup ) ) {
1591                                                         splits[ bSource ][ bGroup ] = [];
1592                                                 }
1593                                                 bSourceGroup = splits[ bSource ][ bGroup ];
1594                                                 bSourceGroup[ bSourceGroup.length ] = batch[ b ];
1595                                         }
1596
1597                                         // Clear the batch - this MUST happen before we append any
1598                                         // script elements to the body or it's possible that a script
1599                                         // will be locally cached, instantly load, and work the batch
1600                                         // again, all before we've cleared it causing each request to
1601                                         // include modules which are already loaded.
1602                                         batch = [];
1603
1604                                         for ( source in splits ) {
1605
1606                                                 sourceLoadScript = sources[ source ];
1607
1608                                                 for ( group in splits[ source ] ) {
1609
1610                                                         // Cache access to currently selected list of
1611                                                         // modules for this group from this source.
1612                                                         modules = splits[ source ][ group ];
1613
1614                                                         currReqBase = $.extend( {
1615                                                                 version: getCombinedVersion( modules )
1616                                                         }, reqBase );
1617                                                         // For user modules append a user name to the request.
1618                                                         if ( group === 'user' && mw.config.get( 'wgUserName' ) !== null ) {
1619                                                                 currReqBase.user = mw.config.get( 'wgUserName' );
1620                                                         }
1621                                                         currReqBaseLength = $.param( currReqBase ).length;
1622                                                         // We may need to split up the request to honor the query string length limit,
1623                                                         // so build it piece by piece.
1624                                                         l = currReqBaseLength + 9; // '&modules='.length == 9
1625
1626                                                         moduleMap = {}; // { prefix: [ suffixes ] }
1627
1628                                                         for ( i = 0; i < modules.length; i += 1 ) {
1629                                                                 // Determine how many bytes this module would add to the query string
1630                                                                 lastDotIndex = modules[ i ].lastIndexOf( '.' );
1631
1632                                                                 // If lastDotIndex is -1, substr() returns an empty string
1633                                                                 prefix = modules[ i ].substr( 0, lastDotIndex );
1634                                                                 suffix = modules[ i ].slice( lastDotIndex + 1 );
1635
1636                                                                 bytesAdded = hasOwn.call( moduleMap, prefix )
1637                                                                         ? suffix.length + 3 // '%2C'.length == 3
1638                                                                         : modules[ i ].length + 3; // '%7C'.length == 3
1639
1640                                                                 // If the request would become too long, create a new one,
1641                                                                 // but don't create empty requests
1642                                                                 if ( maxQueryLength > 0 && !$.isEmptyObject( moduleMap ) && l + bytesAdded > maxQueryLength ) {
1643                                                                         // This request would become too long, create a new one
1644                                                                         // and fire off the old one
1645                                                                         doRequest( moduleMap, currReqBase, sourceLoadScript );
1646                                                                         moduleMap = {};
1647                                                                         l = currReqBaseLength + 9;
1648                                                                         mw.track( 'resourceloader.splitRequest', { maxQueryLength: maxQueryLength } );
1649                                                                 }
1650                                                                 if ( !hasOwn.call( moduleMap, prefix ) ) {
1651                                                                         moduleMap[ prefix ] = [];
1652                                                                 }
1653                                                                 moduleMap[ prefix ].push( suffix );
1654                                                                 l += bytesAdded;
1655                                                         }
1656                                                         // If there's anything left in moduleMap, request that too
1657                                                         if ( !$.isEmptyObject( moduleMap ) ) {
1658                                                                 doRequest( moduleMap, currReqBase, sourceLoadScript );
1659                                                         }
1660                                                 }
1661                                         }
1662                                 },
1663
1664                                 /**
1665                                  * Register a source.
1666                                  *
1667                                  * The #work method will use this information to split up requests by source.
1668                                  *
1669                                  *     mw.loader.addSource( 'mediawikiwiki', '//www.mediawiki.org/w/load.php' );
1670                                  *
1671                                  * @param {string} id Short string representing a source wiki, used internally for
1672                                  *  registered modules to indicate where they should be loaded from (usually lowercase a-z).
1673                                  * @param {Object|string} loadUrl load.php url, may be an object for backwards-compatibility
1674                                  * @return {boolean}
1675                                  */
1676                                 addSource: function ( id, loadUrl ) {
1677                                         var source;
1678                                         // Allow multiple additions
1679                                         if ( typeof id === 'object' ) {
1680                                                 for ( source in id ) {
1681                                                         mw.loader.addSource( source, id[ source ] );
1682                                                 }
1683                                                 return true;
1684                                         }
1685
1686                                         if ( hasOwn.call( sources, id ) ) {
1687                                                 throw new Error( 'source already registered: ' + id );
1688                                         }
1689
1690                                         if ( typeof loadUrl === 'object' ) {
1691                                                 loadUrl = loadUrl.loadScript;
1692                                         }
1693
1694                                         sources[ id ] = loadUrl;
1695
1696                                         return true;
1697                                 },
1698
1699                                 /**
1700                                  * Register a module, letting the system know about it and its properties.
1701                                  *
1702                                  * The startup modules contain calls to this method.
1703                                  *
1704                                  * When using multiple module registration by passing an array, dependencies that
1705                                  * are specified as references to modules within the array will be resolved before
1706                                  * the modules are registered.
1707                                  *
1708                                  * @param {string|Array} module Module name or array of arrays, each containing
1709                                  *  a list of arguments compatible with this method
1710                                  * @param {string|number} version Module version hash (falls backs to empty string)
1711                                  *  Can also be a number (timestamp) for compatibility with MediaWiki 1.25 and earlier.
1712                                  * @param {string|Array|Function} dependencies One string or array of strings of module
1713                                  *  names on which this module depends, or a function that returns that array.
1714                                  * @param {string} [group=null] Group which the module is in
1715                                  * @param {string} [source='local'] Name of the source
1716                                  * @param {string} [skip=null] Script body of the skip function
1717                                  */
1718                                 register: function ( module, version, dependencies, group, source, skip ) {
1719                                         var i, len;
1720                                         // Allow multiple registration
1721                                         if ( typeof module === 'object' ) {
1722                                                 resolveIndexedDependencies( module );
1723                                                 for ( i = 0, len = module.length; i < len; i++ ) {
1724                                                         // module is an array of module names
1725                                                         if ( typeof module[ i ] === 'string' ) {
1726                                                                 mw.loader.register( module[ i ] );
1727                                                         // module is an array of arrays
1728                                                         } else if ( typeof module[ i ] === 'object' ) {
1729                                                                 mw.loader.register.apply( mw.loader, module[ i ] );
1730                                                         }
1731                                                 }
1732                                                 return;
1733                                         }
1734                                         // Validate input
1735                                         if ( typeof module !== 'string' ) {
1736                                                 throw new Error( 'module must be a string, not a ' + typeof module );
1737                                         }
1738                                         if ( hasOwn.call( registry, module ) ) {
1739                                                 throw new Error( 'module already registered: ' + module );
1740                                         }
1741                                         // List the module as registered
1742                                         registry[ module ] = {
1743                                                 version: version !== undefined ? String( version ) : '',
1744                                                 dependencies: [],
1745                                                 group: typeof group === 'string' ? group : null,
1746                                                 source: typeof source === 'string' ? source : 'local',
1747                                                 state: 'registered',
1748                                                 skip: typeof skip === 'string' ? skip : null
1749                                         };
1750                                         if ( typeof dependencies === 'string' ) {
1751                                                 // Allow dependencies to be given as a single module name
1752                                                 registry[ module ].dependencies = [ dependencies ];
1753                                         } else if ( typeof dependencies === 'object' || $.isFunction( dependencies ) ) {
1754                                                 // Allow dependencies to be given as an array of module names
1755                                                 // or a function which returns an array
1756                                                 registry[ module ].dependencies = dependencies;
1757                                         }
1758                                 },
1759
1760                                 /**
1761                                  * Implement a module given the components that make up the module.
1762                                  *
1763                                  * When #load or #using requests one or more modules, the server
1764                                  * response contain calls to this function.
1765                                  *
1766                                  * All arguments are required.
1767                                  *
1768                                  * @param {string} module Name of module
1769                                  * @param {Function|Array} script Function with module code or Array of URLs to
1770                                  *  be used as the src attribute of a new `<script>` tag.
1771                                  * @param {Object} [style] Should follow one of the following patterns:
1772                                  *
1773                                  *     { "css": [css, ..] }
1774                                  *     { "url": { <media>: [url, ..] } }
1775                                  *
1776                                  * And for backwards compatibility (needs to be supported forever due to caching):
1777                                  *
1778                                  *     { <media>: css }
1779                                  *     { <media>: [url, ..] }
1780                                  *
1781                                  * The reason css strings are not concatenated anymore is bug 31676. We now check
1782                                  * whether it's safe to extend the stylesheet.
1783                                  *
1784                                  * @param {Object} [messages] List of key/value pairs to be added to mw#messages.
1785                                  * @param {Object} [templates] List of key/value pairs to be added to mw#templates.
1786                                  */
1787                                 implement: function ( module, script, style, messages, templates ) {
1788                                         // Validate input
1789                                         if ( typeof module !== 'string' ) {
1790                                                 throw new Error( 'module must be of type string, not ' + typeof module );
1791                                         }
1792                                         if ( script && !$.isFunction( script ) && !$.isArray( script ) && typeof script !== 'string' ) {
1793                                                 throw new Error( 'script must be of type function, array, or script; not ' + typeof script );
1794                                         }
1795                                         if ( style && !$.isPlainObject( style ) ) {
1796                                                 throw new Error( 'style must be of type object, not ' + typeof style );
1797                                         }
1798                                         if ( messages && !$.isPlainObject( messages ) ) {
1799                                                 throw new Error( 'messages must be of type object, not a ' + typeof messages );
1800                                         }
1801                                         if ( templates && !$.isPlainObject( templates ) ) {
1802                                                 throw new Error( 'templates must be of type object, not a ' + typeof templates );
1803                                         }
1804                                         // Automatically register module
1805                                         if ( !hasOwn.call( registry, module ) ) {
1806                                                 mw.loader.register( module );
1807                                         }
1808                                         // Check for duplicate implementation
1809                                         if ( hasOwn.call( registry, module ) && registry[ module ].script !== undefined ) {
1810                                                 throw new Error( 'module already implemented: ' + module );
1811                                         }
1812                                         // Attach components
1813                                         registry[ module ].script = script || [];
1814                                         registry[ module ].style = style || {};
1815                                         registry[ module ].messages = messages || {};
1816                                         registry[ module ].templates = templates || {};
1817                                         // The module may already have been marked as erroneous
1818                                         if ( $.inArray( registry[ module ].state, [ 'error', 'missing' ] ) === -1 ) {
1819                                                 registry[ module ].state = 'loaded';
1820                                                 if ( allReady( registry[ module ].dependencies ) ) {
1821                                                         execute( module );
1822                                                 }
1823                                         }
1824                                 },
1825
1826                                 /**
1827                                  * Execute a function as soon as one or more required modules are ready.
1828                                  *
1829                                  * Example of inline dependency on OOjs:
1830                                  *
1831                                  *     mw.loader.using( 'oojs', function () {
1832                                  *         OO.compare( [ 1 ], [ 1 ] );
1833                                  *     } );
1834                                  *
1835                                  * @param {string|Array} dependencies Module name or array of modules names the callback
1836                                  *  dependends on to be ready before executing
1837                                  * @param {Function} [ready] Callback to execute when all dependencies are ready
1838                                  * @param {Function} [error] Callback to execute if one or more dependencies failed
1839                                  * @return {jQuery.Promise}
1840                                  * @since 1.23 this returns a promise
1841                                  */
1842                                 using: function ( dependencies, ready, error ) {
1843                                         var deferred = $.Deferred();
1844
1845                                         // Allow calling with a single dependency as a string
1846                                         if ( typeof dependencies === 'string' ) {
1847                                                 dependencies = [ dependencies ];
1848                                         } else if ( !$.isArray( dependencies ) ) {
1849                                                 // Invalid input
1850                                                 throw new Error( 'Dependencies must be a string or an array' );
1851                                         }
1852
1853                                         if ( ready ) {
1854                                                 deferred.done( ready );
1855                                         }
1856                                         if ( error ) {
1857                                                 deferred.fail( error );
1858                                         }
1859
1860                                         // Resolve entire dependency map
1861                                         dependencies = resolve( dependencies );
1862                                         if ( allReady( dependencies ) ) {
1863                                                 // Run ready immediately
1864                                                 deferred.resolve();
1865                                         } else if ( anyFailed( dependencies ) ) {
1866                                                 // Execute error immediately if any dependencies have errors
1867                                                 deferred.reject(
1868                                                         new Error( 'One or more dependencies failed to load' ),
1869                                                         dependencies
1870                                                 );
1871                                         } else {
1872                                                 // Not all dependencies are ready: queue up a request
1873                                                 request( dependencies, deferred.resolve, deferred.reject );
1874                                         }
1875
1876                                         return deferred.promise();
1877                                 },
1878
1879                                 /**
1880                                  * Load an external script or one or more modules.
1881                                  *
1882                                  * @param {string|Array} modules Either the name of a module, array of modules,
1883                                  *  or a URL of an external script or style
1884                                  * @param {string} [type='text/javascript'] MIME type to use if calling with a URL of an
1885                                  *  external script or style; acceptable values are "text/css" and
1886                                  *  "text/javascript"; if no type is provided, text/javascript is assumed.
1887                                  */
1888                                 load: function ( modules, type ) {
1889                                         var filtered, l;
1890
1891                                         // Validate input
1892                                         if ( typeof modules !== 'object' && typeof modules !== 'string' ) {
1893                                                 throw new Error( 'modules must be a string or an array, not a ' + typeof modules );
1894                                         }
1895                                         // Allow calling with an external url or single dependency as a string
1896                                         if ( typeof modules === 'string' ) {
1897                                                 if ( /^(https?:)?\/\//.test( modules ) ) {
1898                                                         if ( type === 'text/css' ) {
1899                                                                 // Support: IE 7-8
1900                                                                 // Use properties instead of attributes as IE throws security
1901                                                                 // warnings when inserting a <link> tag with a protocol-relative
1902                                                                 // URL set though attributes - when on HTTPS. See bug 41331.
1903                                                                 l = document.createElement( 'link' );
1904                                                                 l.rel = 'stylesheet';
1905                                                                 l.href = modules;
1906                                                                 $( 'head' ).append( l );
1907                                                                 return;
1908                                                         }
1909                                                         if ( type === 'text/javascript' || type === undefined ) {
1910                                                                 addScript( modules );
1911                                                                 return;
1912                                                         }
1913                                                         // Unknown type
1914                                                         throw new Error( 'invalid type for external url, must be text/css or text/javascript. not ' + type );
1915                                                 }
1916                                                 // Called with single module
1917                                                 modules = [ modules ];
1918                                         }
1919
1920                                         // Filter out undefined modules, otherwise resolve() will throw
1921                                         // an exception for trying to load an undefined module.
1922                                         // Undefined modules are acceptable here in load(), because load() takes
1923                                         // an array of unrelated modules, whereas the modules passed to
1924                                         // using() are related and must all be loaded.
1925                                         filtered = $.grep( modules, function ( module ) {
1926                                                 var state = mw.loader.getState( module );
1927                                                 return state !== null && state !== 'error' && state !== 'missing';
1928                                         } );
1929
1930                                         if ( filtered.length === 0 ) {
1931                                                 return;
1932                                         }
1933                                         // Resolve entire dependency map
1934                                         filtered = resolve( filtered );
1935                                         // If all modules are ready, or if any modules have errors, nothing to be done.
1936                                         if ( allReady( filtered ) || anyFailed( filtered ) ) {
1937                                                 return;
1938                                         }
1939                                         // Since some modules are not yet ready, queue up a request.
1940                                         request( filtered, undefined, undefined );
1941                                 },
1942
1943                                 /**
1944                                  * Change the state of one or more modules.
1945                                  *
1946                                  * @param {string|Object} module Module name or object of module name/state pairs
1947                                  * @param {string} state State name
1948                                  */
1949                                 state: function ( module, state ) {
1950                                         var m;
1951
1952                                         if ( typeof module === 'object' ) {
1953                                                 for ( m in module ) {
1954                                                         mw.loader.state( m, module[ m ] );
1955                                                 }
1956                                                 return;
1957                                         }
1958                                         if ( !hasOwn.call( registry, module ) ) {
1959                                                 mw.loader.register( module );
1960                                         }
1961                                         if ( $.inArray( state, [ 'ready', 'error', 'missing' ] ) !== -1
1962                                                 && registry[ module ].state !== state ) {
1963                                                 // Make sure pending modules depending on this one get executed if their
1964                                                 // dependencies are now fulfilled!
1965                                                 registry[ module ].state = state;
1966                                                 handlePending( module );
1967                                         } else {
1968                                                 registry[ module ].state = state;
1969                                         }
1970                                 },
1971
1972                                 /**
1973                                  * Get the version of a module.
1974                                  *
1975                                  * @param {string} module Name of module
1976                                  * @return {string|null} The version, or null if the module (or its version) is not
1977                                  *  in the registry.
1978                                  */
1979                                 getVersion: function ( module ) {
1980                                         if ( !hasOwn.call( registry, module ) || registry[ module ].version === undefined ) {
1981                                                 return null;
1982                                         }
1983                                         return registry[ module ].version;
1984                                 },
1985
1986                                 /**
1987                                  * Get the state of a module.
1988                                  *
1989                                  * @param {string} module Name of module
1990                                  * @return {string|null} The state, or null if the module (or its state) is not
1991                                  *  in the registry.
1992                                  */
1993                                 getState: function ( module ) {
1994                                         if ( !hasOwn.call( registry, module ) || registry[ module ].state === undefined ) {
1995                                                 return null;
1996                                         }
1997                                         return registry[ module ].state;
1998                                 },
1999
2000                                 /**
2001                                  * Get the names of all registered modules.
2002                                  *
2003                                  * @return {Array}
2004                                  */
2005                                 getModuleNames: function () {
2006                                         return $.map( registry, function ( i, key ) {
2007                                                 return key;
2008                                         } );
2009                                 },
2010
2011                                 /**
2012                                  * @inheritdoc mw.inspect#runReports
2013                                  * @method
2014                                  */
2015                                 inspect: function () {
2016                                         var args = slice.call( arguments );
2017                                         mw.loader.using( 'mediawiki.inspect', function () {
2018                                                 mw.inspect.runReports.apply( mw.inspect, args );
2019                                         } );
2020                                 },
2021
2022                                 /**
2023                                  * On browsers that implement the localStorage API, the module store serves as a
2024                                  * smart complement to the browser cache. Unlike the browser cache, the module store
2025                                  * can slice a concatenated response from ResourceLoader into its constituent
2026                                  * modules and cache each of them separately, using each module's versioning scheme
2027                                  * to determine when the cache should be invalidated.
2028                                  *
2029                                  * @singleton
2030                                  * @class mw.loader.store
2031                                  */
2032                                 store: {
2033                                         // Whether the store is in use on this page.
2034                                         enabled: null,
2035
2036                                         // Modules whose string representation exceeds 100 kB are ineligible
2037                                         // for storage due to bug T66721.
2038                                         MODULE_SIZE_MAX: 100000,
2039
2040                                         // The contents of the store, mapping '[module name]@[version]' keys
2041                                         // to module implementations.
2042                                         items: {},
2043
2044                                         // Cache hit stats
2045                                         stats: { hits: 0, misses: 0, expired: 0 },
2046
2047                                         /**
2048                                          * Construct a JSON-serializable object representing the content of the store.
2049                                          *
2050                                          * @return {Object} Module store contents.
2051                                          */
2052                                         toJSON: function () {
2053                                                 return { items: mw.loader.store.items, vary: mw.loader.store.getVary() };
2054                                         },
2055
2056                                         /**
2057                                          * Get the localStorage key for the entire module store. The key references
2058                                          * $wgDBname to prevent clashes between wikis which share a common host.
2059                                          *
2060                                          * @return {string} localStorage item key
2061                                          */
2062                                         getStoreKey: function () {
2063                                                 return 'MediaWikiModuleStore:' + mw.config.get( 'wgDBname' );
2064                                         },
2065
2066                                         /**
2067                                          * Get a key on which to vary the module cache.
2068                                          *
2069                                          * @return {string} String of concatenated vary conditions.
2070                                          */
2071                                         getVary: function () {
2072                                                 return [
2073                                                         mw.config.get( 'skin' ),
2074                                                         mw.config.get( 'wgResourceLoaderStorageVersion' ),
2075                                                         mw.config.get( 'wgUserLanguage' )
2076                                                 ].join( ':' );
2077                                         },
2078
2079                                         /**
2080                                          * Get a key for a specific module. The key format is '[name]@[version]'.
2081                                          *
2082                                          * @param {string} module Module name
2083                                          * @return {string|null} Module key or null if module does not exist
2084                                          */
2085                                         getModuleKey: function ( module ) {
2086                                                 return hasOwn.call( registry, module ) ?
2087                                                         ( module + '@' + registry[ module ].version ) : null;
2088                                         },
2089
2090                                         /**
2091                                          * Initialize the store.
2092                                          *
2093                                          * Retrieves store from localStorage and (if successfully retrieved) decoding
2094                                          * the stored JSON value to a plain object.
2095                                          *
2096                                          * The try / catch block is used for JSON & localStorage feature detection.
2097                                          * See the in-line documentation for Modernizr's localStorage feature detection
2098                                          * code for a full account of why we need a try / catch:
2099                                          * <https://github.com/Modernizr/Modernizr/blob/v2.7.1/modernizr.js#L771-L796>.
2100                                          */
2101                                         init: function () {
2102                                                 var raw, data;
2103
2104                                                 if ( mw.loader.store.enabled !== null ) {
2105                                                         // Init already ran
2106                                                         return;
2107                                                 }
2108
2109                                                 if ( !mw.config.get( 'wgResourceLoaderStorageEnabled' ) ) {
2110                                                         // Disabled by configuration.
2111                                                         // Clear any previous store to free up space. (T66721)
2112                                                         mw.loader.store.clear();
2113                                                         mw.loader.store.enabled = false;
2114                                                         return;
2115                                                 }
2116                                                 if ( mw.config.get( 'debug' ) ) {
2117                                                         // Disable module store in debug mode
2118                                                         mw.loader.store.enabled = false;
2119                                                         return;
2120                                                 }
2121
2122                                                 try {
2123                                                         raw = localStorage.getItem( mw.loader.store.getStoreKey() );
2124                                                         // If we get here, localStorage is available; mark enabled
2125                                                         mw.loader.store.enabled = true;
2126                                                         data = JSON.parse( raw );
2127                                                         if ( data && typeof data.items === 'object' && data.vary === mw.loader.store.getVary() ) {
2128                                                                 mw.loader.store.items = data.items;
2129                                                                 return;
2130                                                         }
2131                                                 } catch ( e ) {
2132                                                         mw.track( 'resourceloader.exception', { exception: e, source: 'store-localstorage-init' } );
2133                                                 }
2134
2135                                                 if ( raw === undefined ) {
2136                                                         // localStorage failed; disable store
2137                                                         mw.loader.store.enabled = false;
2138                                                 } else {
2139                                                         mw.loader.store.update();
2140                                                 }
2141                                         },
2142
2143                                         /**
2144                                          * Retrieve a module from the store and update cache hit stats.
2145                                          *
2146                                          * @param {string} module Module name
2147                                          * @return {string|boolean} Module implementation or false if unavailable
2148                                          */
2149                                         get: function ( module ) {
2150                                                 var key;
2151
2152                                                 if ( !mw.loader.store.enabled ) {
2153                                                         return false;
2154                                                 }
2155
2156                                                 key = mw.loader.store.getModuleKey( module );
2157                                                 if ( key in mw.loader.store.items ) {
2158                                                         mw.loader.store.stats.hits++;
2159                                                         return mw.loader.store.items[ key ];
2160                                                 }
2161                                                 mw.loader.store.stats.misses++;
2162                                                 return false;
2163                                         },
2164
2165                                         /**
2166                                          * Stringify a module and queue it for storage.
2167                                          *
2168                                          * @param {string} module Module name
2169                                          * @param {Object} descriptor The module's descriptor as set in the registry
2170                                          */
2171                                         set: function ( module, descriptor ) {
2172                                                 var args, key, src;
2173
2174                                                 if ( !mw.loader.store.enabled ) {
2175                                                         return false;
2176                                                 }
2177
2178                                                 key = mw.loader.store.getModuleKey( module );
2179
2180                                                 if (
2181                                                         // Already stored a copy of this exact version
2182                                                         key in mw.loader.store.items ||
2183                                                         // Module failed to load
2184                                                         descriptor.state !== 'ready' ||
2185                                                         // Unversioned, private, or site-/user-specific
2186                                                         ( !descriptor.version || $.inArray( descriptor.group, [ 'private', 'user' ] ) !== -1 ) ||
2187                                                         // Partial descriptor
2188                                                         $.inArray( undefined, [ descriptor.script, descriptor.style,
2189                                                                         descriptor.messages, descriptor.templates ] ) !== -1
2190                                                 ) {
2191                                                         // Decline to store
2192                                                         return false;
2193                                                 }
2194
2195                                                 try {
2196                                                         args = [
2197                                                                 JSON.stringify( module ),
2198                                                                 typeof descriptor.script === 'function' ?
2199                                                                         String( descriptor.script ) :
2200                                                                         JSON.stringify( descriptor.script ),
2201                                                                 JSON.stringify( descriptor.style ),
2202                                                                 JSON.stringify( descriptor.messages ),
2203                                                                 JSON.stringify( descriptor.templates )
2204                                                         ];
2205                                                         // Attempted workaround for a possible Opera bug (bug T59567).
2206                                                         // This regex should never match under sane conditions.
2207                                                         if ( /^\s*\(/.test( args[ 1 ] ) ) {
2208                                                                 args[ 1 ] = 'function' + args[ 1 ];
2209                                                                 mw.track( 'resourceloader.assert', { source: 'bug-T59567' } );
2210                                                         }
2211                                                 } catch ( e ) {
2212                                                         mw.track( 'resourceloader.exception', { exception: e, source: 'store-localstorage-json' } );
2213                                                         return;
2214                                                 }
2215
2216                                                 src = 'mw.loader.implement(' + args.join( ',' ) + ');';
2217                                                 if ( src.length > mw.loader.store.MODULE_SIZE_MAX ) {
2218                                                         return false;
2219                                                 }
2220                                                 mw.loader.store.items[ key ] = src;
2221                                                 mw.loader.store.update();
2222                                         },
2223
2224                                         /**
2225                                          * Iterate through the module store, removing any item that does not correspond
2226                                          * (in name and version) to an item in the module registry.
2227                                          */
2228                                         prune: function () {
2229                                                 var key, module;
2230
2231                                                 if ( !mw.loader.store.enabled ) {
2232                                                         return false;
2233                                                 }
2234
2235                                                 for ( key in mw.loader.store.items ) {
2236                                                         module = key.slice( 0, key.indexOf( '@' ) );
2237                                                         if ( mw.loader.store.getModuleKey( module ) !== key ) {
2238                                                                 mw.loader.store.stats.expired++;
2239                                                                 delete mw.loader.store.items[ key ];
2240                                                         } else if ( mw.loader.store.items[ key ].length > mw.loader.store.MODULE_SIZE_MAX ) {
2241                                                                 // This value predates the enforcement of a size limit on cached modules.
2242                                                                 delete mw.loader.store.items[ key ];
2243                                                         }
2244                                                 }
2245                                         },
2246
2247                                         /**
2248                                          * Clear the entire module store right now.
2249                                          */
2250                                         clear: function () {
2251                                                 mw.loader.store.items = {};
2252                                                 localStorage.removeItem( mw.loader.store.getStoreKey() );
2253                                         },
2254
2255                                         /**
2256                                          * Sync modules to localStorage.
2257                                          *
2258                                          * This function debounces localStorage updates. When called multiple times in
2259                                          * quick succession, the calls are coalesced into a single update operation.
2260                                          * This allows us to call #update without having to consider the module load
2261                                          * queue; the call to localStorage.setItem will be naturally deferred until the
2262                                          * page is quiescent.
2263                                          *
2264                                          * Because localStorage is shared by all pages with the same origin, if multiple
2265                                          * pages are loaded with different module sets, the possibility exists that
2266                                          * modules saved by one page will be clobbered by another. But the impact would
2267                                          * be minor and the problem would be corrected by subsequent page views.
2268                                          *
2269                                          * @method
2270                                          */
2271                                         update: ( function () {
2272                                                 var timer;
2273
2274                                                 function flush() {
2275                                                         var data,
2276                                                                 key = mw.loader.store.getStoreKey();
2277
2278                                                         if ( !mw.loader.store.enabled ) {
2279                                                                 return false;
2280                                                         }
2281                                                         mw.loader.store.prune();
2282                                                         try {
2283                                                                 // Replacing the content of the module store might fail if the new
2284                                                                 // contents would exceed the browser's localStorage size limit. To
2285                                                                 // avoid clogging the browser with stale data, always remove the old
2286                                                                 // value before attempting to set the new one.
2287                                                                 localStorage.removeItem( key );
2288                                                                 data = JSON.stringify( mw.loader.store );
2289                                                                 localStorage.setItem( key, data );
2290                                                         } catch ( e ) {
2291                                                                 mw.track( 'resourceloader.exception', { exception: e, source: 'store-localstorage-update' } );
2292                                                         }
2293                                                 }
2294
2295                                                 return function () {
2296                                                         clearTimeout( timer );
2297                                                         timer = setTimeout( flush, 2000 );
2298                                                 };
2299                                         }() )
2300                                 }
2301                         };
2302                 }() ),
2303
2304                 /**
2305                  * HTML construction helper functions
2306                  *
2307                  *     @example
2308                  *
2309                  *     var Html, output;
2310                  *
2311                  *     Html = mw.html;
2312                  *     output = Html.element( 'div', {}, new Html.Raw(
2313                  *         Html.element( 'img', { src: '<' } )
2314                  *     ) );
2315                  *     mw.log( output ); // <div><img src="&lt;"/></div>
2316                  *
2317                  * @class mw.html
2318                  * @singleton
2319                  */
2320                 html: ( function () {
2321                         function escapeCallback( s ) {
2322                                 switch ( s ) {
2323                                         case '\'':
2324                                                 return '&#039;';
2325                                         case '"':
2326                                                 return '&quot;';
2327                                         case '<':
2328                                                 return '&lt;';
2329                                         case '>':
2330                                                 return '&gt;';
2331                                         case '&':
2332                                                 return '&amp;';
2333                                 }
2334                         }
2335
2336                         return {
2337                                 /**
2338                                  * Escape a string for HTML.
2339                                  *
2340                                  * Converts special characters to HTML entities.
2341                                  *
2342                                  *     mw.html.escape( '< > \' & "' );
2343                                  *     // Returns &lt; &gt; &#039; &amp; &quot;
2344                                  *
2345                                  * @param {string} s The string to escape
2346                                  * @return {string} HTML
2347                                  */
2348                                 escape: function ( s ) {
2349                                         return s.replace( /['"<>&]/g, escapeCallback );
2350                                 },
2351
2352                                 /**
2353                                  * Create an HTML element string, with safe escaping.
2354                                  *
2355                                  * @param {string} name The tag name.
2356                                  * @param {Object} attrs An object with members mapping element names to values
2357                                  * @param {Mixed} contents The contents of the element. May be either:
2358                                  *
2359                                  *  - string: The string is escaped.
2360                                  *  - null or undefined: The short closing form is used, e.g. `<br/>`.
2361                                  *  - this.Raw: The value attribute is included without escaping.
2362                                  *  - this.Cdata: The value attribute is included, and an exception is
2363                                  *    thrown if it contains an illegal ETAGO delimiter.
2364                                  *    See <http://www.w3.org/TR/1999/REC-html401-19991224/appendix/notes.html#h-B.3.2>.
2365                                  * @return {string} HTML
2366                                  */
2367                                 element: function ( name, attrs, contents ) {
2368                                         var v, attrName, s = '<' + name;
2369
2370                                         for ( attrName in attrs ) {
2371                                                 v = attrs[ attrName ];
2372                                                 // Convert name=true, to name=name
2373                                                 if ( v === true ) {
2374                                                         v = attrName;
2375                                                 // Skip name=false
2376                                                 } else if ( v === false ) {
2377                                                         continue;
2378                                                 }
2379                                                 s += ' ' + attrName + '="' + this.escape( String( v ) ) + '"';
2380                                         }
2381                                         if ( contents === undefined || contents === null ) {
2382                                                 // Self close tag
2383                                                 s += '/>';
2384                                                 return s;
2385                                         }
2386                                         // Regular open tag
2387                                         s += '>';
2388                                         switch ( typeof contents ) {
2389                                                 case 'string':
2390                                                         // Escaped
2391                                                         s += this.escape( contents );
2392                                                         break;
2393                                                 case 'number':
2394                                                 case 'boolean':
2395                                                         // Convert to string
2396                                                         s += String( contents );
2397                                                         break;
2398                                                 default:
2399                                                         if ( contents instanceof this.Raw ) {
2400                                                                 // Raw HTML inclusion
2401                                                                 s += contents.value;
2402                                                         } else if ( contents instanceof this.Cdata ) {
2403                                                                 // CDATA
2404                                                                 if ( /<\/[a-zA-z]/.test( contents.value ) ) {
2405                                                                         throw new Error( 'mw.html.element: Illegal end tag found in CDATA' );
2406                                                                 }
2407                                                                 s += contents.value;
2408                                                         } else {
2409                                                                 throw new Error( 'mw.html.element: Invalid type of contents' );
2410                                                         }
2411                                         }
2412                                         s += '</' + name + '>';
2413                                         return s;
2414                                 },
2415
2416                                 /**
2417                                  * Wrapper object for raw HTML passed to mw.html.element().
2418                                  *
2419                                  * @class mw.html.Raw
2420                                  */
2421                                 Raw: function ( value ) {
2422                                         this.value = value;
2423                                 },
2424
2425                                 /**
2426                                  * Wrapper object for CDATA element contents passed to mw.html.element()
2427                                  *
2428                                  * @class mw.html.Cdata
2429                                  */
2430                                 Cdata: function ( value ) {
2431                                         this.value = value;
2432                                 }
2433                         };
2434                 }() ),
2435
2436                 // Skeleton user object. mediawiki.user.js extends this
2437                 user: {
2438                         options: new Map(),
2439                         tokens: new Map()
2440                 },
2441
2442                 /**
2443                  * Registry and firing of events.
2444                  *
2445                  * MediaWiki has various interface components that are extended, enhanced
2446                  * or manipulated in some other way by extensions, gadgets and even
2447                  * in core itself.
2448                  *
2449                  * This framework helps streamlining the timing of when these other
2450                  * code paths fire their plugins (instead of using document-ready,
2451                  * which can and should be limited to firing only once).
2452                  *
2453                  * Features like navigating to other wiki pages, previewing an edit
2454                  * and editing itself – without a refresh – can then retrigger these
2455                  * hooks accordingly to ensure everything still works as expected.
2456                  *
2457                  * Example usage:
2458                  *
2459                  *     mw.hook( 'wikipage.content' ).add( fn ).remove( fn );
2460                  *     mw.hook( 'wikipage.content' ).fire( $content );
2461                  *
2462                  * Handlers can be added and fired for arbitrary event names at any time. The same
2463                  * event can be fired multiple times. The last run of an event is memorized
2464                  * (similar to `$(document).ready` and `$.Deferred().done`).
2465                  * This means if an event is fired, and a handler added afterwards, the added
2466                  * function will be fired right away with the last given event data.
2467                  *
2468                  * Like Deferreds and Promises, the mw.hook object is both detachable and chainable.
2469                  * Thus allowing flexible use and optimal maintainability and authority control.
2470                  * You can pass around the `add` and/or `fire` method to another piece of code
2471                  * without it having to know the event name (or `mw.hook` for that matter).
2472                  *
2473                  *     var h = mw.hook( 'bar.ready' );
2474                  *     new mw.Foo( .. ).fetch( { callback: h.fire } );
2475                  *
2476                  * Note: Events are documented with an underscore instead of a dot in the event
2477                  * name due to jsduck not supporting dots in that position.
2478                  *
2479                  * @class mw.hook
2480                  */
2481                 hook: ( function () {
2482                         var lists = {};
2483
2484                         /**
2485                          * Create an instance of mw.hook.
2486                          *
2487                          * @method hook
2488                          * @member mw
2489                          * @param {string} name Name of hook.
2490                          * @return {mw.hook}
2491                          */
2492                         return function ( name ) {
2493                                 var list = hasOwn.call( lists, name ) ?
2494                                         lists[ name ] :
2495                                         lists[ name ] = $.Callbacks( 'memory' );
2496
2497                                 return {
2498                                         /**
2499                                          * Register a hook handler
2500                                          *
2501                                          * @param {Function...} handler Function to bind.
2502                                          * @chainable
2503                                          */
2504                                         add: list.add,
2505
2506                                         /**
2507                                          * Unregister a hook handler
2508                                          *
2509                                          * @param {Function...} handler Function to unbind.
2510                                          * @chainable
2511                                          */
2512                                         remove: list.remove,
2513
2514                                         /**
2515                                          * Run a hook.
2516                                          *
2517                                          * @param {Mixed...} data
2518                                          * @chainable
2519                                          */
2520                                         fire: function () {
2521                                                 return list.fireWith.call( this, null, slice.call( arguments ) );
2522                                         }
2523                                 };
2524                         };
2525                 }() )
2526         };
2527
2528         // Alias $j to jQuery for backwards compatibility
2529         // @deprecated since 1.23 Use $ or jQuery instead
2530         mw.log.deprecate( window, '$j', $, 'Use $ or jQuery instead.' );
2531
2532         /**
2533          * Log a message to window.console, if possible.
2534          *
2535          * Useful to force logging of some  errors that are otherwise hard to detect (i.e., this logs
2536          * also in production mode). Gets console references in each invocation instead of caching the
2537          * reference, so that debugging tools loaded later are supported (e.g. Firebug Lite in IE).
2538          *
2539          * @private
2540          * @method log_
2541          * @param {string} topic Stream name passed by mw.track
2542          * @param {Object} data Data passed by mw.track
2543          * @param {Error} [data.exception]
2544          * @param {string} data.source Error source
2545          * @param {string} [data.module] Name of module which caused the error
2546          */
2547         function log( topic, data ) {
2548                 var msg,
2549                         e = data.exception,
2550                         source = data.source,
2551                         module = data.module,
2552                         console = window.console;
2553
2554                 if ( console && console.log ) {
2555                         msg = ( e ? 'Exception' : 'Error' ) + ' in ' + source;
2556                         if ( module ) {
2557                                 msg += ' in module ' + module;
2558                         }
2559                         msg += ( e ? ':' : '.' );
2560                         console.log( msg );
2561
2562                         // If we have an exception object, log it to the error channel to trigger a
2563                         // proper stacktraces in browsers that support it. No fallback as we have no browsers
2564                         // that don't support error(), but do support log().
2565                         if ( e && console.error ) {
2566                                 console.error( String( e ), e );
2567                         }
2568                 }
2569         }
2570
2571         // subscribe to error streams
2572         mw.trackSubscribe( 'resourceloader.exception', log );
2573         mw.trackSubscribe( 'resourceloader.assert', log );
2574
2575         // Attach to window and globally alias
2576         window.mw = window.mediaWiki = mw;
2577 }( jQuery ) );