resources/src/mediawiki.Title/Title.js

   1 /*!
   2  * @author Neil Kandalgaonkar, 2010
   3  * @since 1.18
   4  */
   5
   6 /**
   7  * Parse titles into an object structure. Note that when using the constructor
   8  * directly, passing invalid titles will result in an exception. Use #newFromText to use the
   9  * logic directly and get null for invalid titles which is easier to work with.
  10  *
  11  * Note that in the constructor and #newFromText method, `namespace` is the **default** namespace
  12  * only, and can be overridden by a namespace prefix in `title`. If you do not want this behavior,
  13  * use #makeTitle. Compare:
  14  *
  15  *     new mw.Title( 'Foo', NS_TEMPLATE ).getPrefixedText();                  // => 'Template:Foo'
  16  *     mw.Title.newFromText( 'Foo', NS_TEMPLATE ).getPrefixedText();          // => 'Template:Foo'
  17  *     mw.Title.makeTitle( NS_TEMPLATE, 'Foo' ).getPrefixedText();            // => 'Template:Foo'
  18  *
  19  *     new mw.Title( 'Category:Foo', NS_TEMPLATE ).getPrefixedText();         // => 'Category:Foo'
  20  *     mw.Title.newFromText( 'Category:Foo', NS_TEMPLATE ).getPrefixedText(); // => 'Category:Foo'
  21  *     mw.Title.makeTitle( NS_TEMPLATE, 'Category:Foo' ).getPrefixedText();   // => 'Template:Category:Foo'
  22  *
  23  *     new mw.Title( 'Template:Foo', NS_TEMPLATE ).getPrefixedText();         // => 'Template:Foo'
  24  *     mw.Title.newFromText( 'Template:Foo', NS_TEMPLATE ).getPrefixedText(); // => 'Template:Foo'
  25  *     mw.Title.makeTitle( NS_TEMPLATE, 'Template:Foo' ).getPrefixedText();   // => 'Template:Template:Foo'
  26  *
  27  * @class mw.Title
  28  */
  29
  30 /* Private members */
  31
  32 var
  33         mwString = require( 'mediawiki.String' ),
  34
  35         toUpperMapping = require( './phpCharToUpper.json' ),
  36
  37         namespaceIds = mw.config.get( 'wgNamespaceIds' ),
  38
  39         /**
  40          * @private
  41          * @static
  42          * @property NS_MAIN
  43          */
  44         NS_MAIN = namespaceIds[ '' ],
  45
  46         /**
  47          * @private
  48          * @static
  49          * @property NS_TALK
  50          */
  51         NS_TALK = namespaceIds.talk,
  52
  53         /**
  54          * @private
  55          * @static
  56          * @property NS_SPECIAL
  57          */
  58         NS_SPECIAL = namespaceIds.special,
  59
  60         /**
  61          * @private
  62          * @static
  63          * @property NS_MEDIA
  64          */
  65         NS_MEDIA = namespaceIds.media,
  66
  67         /**
  68          * @private
  69          * @static
  70          * @property NS_FILE
  71          */
  72         NS_FILE = namespaceIds.file,
  73
  74         /**
  75          * @private
  76          * @static
  77          * @property FILENAME_MAX_BYTES
  78          */
  79         FILENAME_MAX_BYTES = 240,
  80
  81         /**
  82          * @private
  83          * @static
  84          * @property TITLE_MAX_BYTES
  85          */
  86         TITLE_MAX_BYTES = 255,
  87
  88         /**
  89          * Get the namespace id from a namespace name (either from the localized, canonical or alias
  90          * name).
  91          *
  92          * Example: On a German wiki this would return 6 for any of 'File', 'Datei', 'Image' or
  93          * even 'Bild'.
  94          *
  95          * @private
  96          * @static
  97          * @method getNsIdByName
  98          * @param {string} ns Namespace name (case insensitive, leading/trailing space ignored)
  99          * @return {number|boolean} Namespace id or boolean false
 100          */
 101         getNsIdByName = function ( ns ) {
 102                 var id;
 103
 104                 // Don't cast non-strings to strings, because null or undefined should not result in
 105                 // returning the id of a potential namespace called "Null:" (e.g. on null.example.org/wiki)
 106                 // Also, toLowerCase throws exception on null/undefined, because it is a String method.
 107                 if ( typeof ns !== 'string' ) {
 108                         return false;
 109                 }
 110                 // TODO: Should just use local var namespaceIds here but it
 111                 // breaks test which modify the config
 112                 id = mw.config.get( 'wgNamespaceIds' )[ ns.toLowerCase() ];
 113                 if ( id === undefined ) {
 114                         return false;
 115                 }
 116                 return id;
 117         },
 118
 119         /**
 120          * @private
 121          * @method getNamespacePrefix_
 122          * @param {number} namespace
 123          * @return {string}
 124          */
 125         getNamespacePrefix = function ( namespace ) {
 126                 return namespace === NS_MAIN ?
 127                         '' :
 128                         ( mw.config.get( 'wgFormattedNamespaces' )[ namespace ].replace( / /g, '_' ) + ':' );
 129         },
 130
 131         rUnderscoreTrim = /^_+|_+$/g,
 132
 133         rSplit = /^(.+?)_*:_*(.*)$/,
 134
 135         // See MediaWikiTitleCodec.php#getTitleInvalidRegex
 136         rInvalid = new RegExp(
 137                 '[^' + mw.config.get( 'wgLegalTitleChars' ) + ']' +
 138                 // URL percent encoding sequences interfere with the ability
 139                 // to round-trip titles -- you can't link to them consistently.
 140                 '|%[0-9A-Fa-f]{2}' +
 141                 // XML/HTML character references produce similar issues.
 142                 '|&[A-Za-z0-9\u0080-\uFFFF]+;' +
 143                 '|&#[0-9]+;' +
 144                 '|&#x[0-9A-Fa-f]+;'
 145         ),
 146
 147         // From MediaWikiTitleCodec::splitTitleString() in PHP
 148         // Note that this is not equivalent to /\s/, e.g. underscore is included, tab is not included.
 149         rWhitespace = /[ _\u00A0\u1680\u180E\u2000-\u200A\u2028\u2029\u202F\u205F\u3000]+/g,
 150
 151         // From MediaWikiTitleCodec::splitTitleString() in PHP
 152         rUnicodeBidi = /[\u200E\u200F\u202A-\u202E]/g,
 153
 154         /**
 155          * Slightly modified from Flinfo. Credit goes to Lupo and Flominator.
 156          * @private
 157          * @static
 158          * @property sanitationRules
 159          */
 160         sanitationRules = [
 161                 // "signature"
 162                 {
 163                         pattern: /~{3}/g,
 164                         replace: '',
 165                         generalRule: true
 166                 },
 167                 // control characters
 168                 {
 169                         // eslint-disable-next-line no-control-regex
 170                         pattern: /[\x00-\x1f\x7f]/g,
 171                         replace: '',
 172                         generalRule: true
 173                 },
 174                 // URL encoding (possibly)
 175                 {
 176                         pattern: /%([0-9A-Fa-f]{2})/g,
 177                         replace: '% $1',
 178                         generalRule: true
 179                 },
 180                 // HTML-character-entities
 181                 {
 182                         pattern: /&(([A-Za-z0-9\x80-\xff]+|#[0-9]+|#x[0-9A-Fa-f]+);)/g,
 183                         replace: '& $1',
 184                         generalRule: true
 185                 },
 186                 // slash, colon (not supported by file systems like NTFS/Windows, Mac OS 9 [:], ext4 [/])
 187                 {
 188                         pattern: new RegExp( '[' + mw.config.get( 'wgIllegalFileChars', '' ) + ']', 'g' ),
 189                         replace: '-',
 190                         fileRule: true
 191                 },
 192                 // brackets, greater than
 193                 {
 194                         pattern: /[}\]>]/g,
 195                         replace: ')',
 196                         generalRule: true
 197                 },
 198                 // brackets, lower than
 199                 {
 200                         pattern: /[{[<]/g,
 201                         replace: '(',
 202                         generalRule: true
 203                 },
 204                 // everything that wasn't covered yet
 205                 {
 206                         pattern: new RegExp( rInvalid.source, 'g' ),
 207                         replace: '-',
 208                         generalRule: true
 209                 },
 210                 // directory structures
 211                 {
 212                         pattern: /^(\.|\.\.|\.\/.*|\.\.\/.*|.*\/\.\/.*|.*\/\.\.\/.*|.*\/\.|.*\/\.\.)$/g,
 213                         replace: '',
 214                         generalRule: true
 215                 }
 216         ],
 217
 218         /**
 219          * Internal helper for #constructor and #newFromText.
 220          *
 221          * Based on Title.php#secureAndSplit
 222          *
 223          * @private
 224          * @static
 225          * @method parse
 226          * @param {string} title
 227          * @param {number} [defaultNamespace=NS_MAIN]
 228          * @return {Object|boolean}
 229          */
 230         parse = function ( title, defaultNamespace ) {
 231                 var namespace, m, id, i, fragment;
 232
 233                 namespace = defaultNamespace === undefined ? NS_MAIN : defaultNamespace;
 234
 235                 title = title
 236                         // Strip Unicode bidi override characters
 237                         .replace( rUnicodeBidi, '' )
 238                         // Normalise whitespace to underscores and remove duplicates
 239                         .replace( rWhitespace, '_' )
 240                         // Trim underscores
 241                         .replace( rUnderscoreTrim, '' );
 242
 243                 // Process initial colon
 244                 if ( title !== '' && title[ 0 ] === ':' ) {
 245                         // Initial colon means main namespace instead of specified default
 246                         namespace = NS_MAIN;
 247                         title = title
 248                                 // Strip colon
 249                                 .slice( 1 )
 250                                 // Trim underscores
 251                                 .replace( rUnderscoreTrim, '' );
 252                 }
 253
 254                 if ( title === '' ) {
 255                         return false;
 256                 }
 257
 258                 // Process namespace prefix (if any)
 259                 m = title.match( rSplit );
 260                 if ( m ) {
 261                         id = getNsIdByName( m[ 1 ] );
 262                         if ( id !== false ) {
 263                                 // Ordinary namespace
 264                                 namespace = id;
 265                                 title = m[ 2 ];
 266
 267                                 // For Talk:X pages, make sure X has no "namespace" prefix
 268                                 if ( namespace === NS_TALK && ( m = title.match( rSplit ) ) ) {
 269                                         // Disallow titles like Talk:File:x (subject should roundtrip: talk:file:x -> file:x -> file_talk:x)
 270                                         if ( getNsIdByName( m[ 1 ] ) !== false ) {
 271                                                 return false;
 272                                         }
 273                                 }
 274                         }
 275                 }
 276
 277                 // Process fragment
 278                 i = title.indexOf( '#' );
 279                 if ( i === -1 ) {
 280                         fragment = null;
 281                 } else {
 282                         fragment = title
 283                                 // Get segment starting after the hash
 284                                 .slice( i + 1 )
 285                                 // Convert to text
 286                                 // NB: Must not be trimmed ("Example#_foo" is not the same as "Example#foo")
 287                                 .replace( /_/g, ' ' );
 288
 289                         title = title
 290                                 // Strip hash
 291                                 .slice( 0, i )
 292                                 // Trim underscores, again (strips "_" from "bar" in "Foo_bar_#quux")
 293                                 .replace( rUnderscoreTrim, '' );
 294                 }
 295
 296                 // Reject illegal characters
 297                 if ( title.match( rInvalid ) ) {
 298                         return false;
 299                 }
 300
 301                 // Disallow titles that browsers or servers might resolve as directory navigation
 302                 if (
 303                         title.indexOf( '.' ) !== -1 && (
 304                                 title === '.' || title === '..' ||
 305                                 title.indexOf( './' ) === 0 ||
 306                                 title.indexOf( '../' ) === 0 ||
 307                                 title.indexOf( '/./' ) !== -1 ||
 308                                 title.indexOf( '/../' ) !== -1 ||
 309                                 title.slice( -2 ) === '/.' ||
 310                                 title.slice( -3 ) === '/..'
 311                         )
 312                 ) {
 313                         return false;
 314                 }
 315
 316                 // Disallow magic tilde sequence
 317                 if ( title.indexOf( '~~~' ) !== -1 ) {
 318                         return false;
 319                 }
 320
 321                 // Disallow titles exceeding the TITLE_MAX_BYTES byte size limit (size of underlying database field)
 322                 // Except for special pages, e.g. [[Special:Block/Long name]]
 323                 // Note: The PHP implementation also asserts that even in NS_SPECIAL, the title should
 324                 // be less than 512 bytes.
 325                 if ( namespace !== NS_SPECIAL && mwString.byteLength( title ) > TITLE_MAX_BYTES ) {
 326                         return false;
 327                 }
 328
 329                 // Can't make a link to a namespace alone.
 330                 if ( title === '' && namespace !== NS_MAIN ) {
 331                         return false;
 332                 }
 333
 334                 // Any remaining initial :s are illegal.
 335                 if ( title[ 0 ] === ':' ) {
 336                         return false;
 337                 }
 338
 339                 return {
 340                         namespace: namespace,
 341                         title: title,
 342                         fragment: fragment
 343                 };
 344         },
 345
 346         /**
 347          * Convert db-key to readable text.
 348          *
 349          * @private
 350          * @static
 351          * @method text
 352          * @param {string} s
 353          * @return {string}
 354          */
 355         text = function ( s ) {
 356                 return s.replace( /_/g, ' ' );
 357         },
 358
 359         /**
 360          * Sanitizes a string based on a rule set and a filter
 361          *
 362          * @private
 363          * @static
 364          * @method sanitize
 365          * @param {string} s
 366          * @param {Array} filter
 367          * @return {string}
 368          */
 369         sanitize = function ( s, filter ) {
 370                 var i, ruleLength, rule, m, filterLength,
 371                         rules = sanitationRules;
 372
 373                 for ( i = 0, ruleLength = rules.length; i < ruleLength; ++i ) {
 374                         rule = rules[ i ];
 375                         for ( m = 0, filterLength = filter.length; m < filterLength; ++m ) {
 376                                 if ( rule[ filter[ m ] ] ) {
 377                                         s = s.replace( rule.pattern, rule.replace );
 378                                 }
 379                         }
 380                 }
 381                 return s;
 382         },
 383
 384         /**
 385          * Cuts a string to a specific byte length, assuming UTF-8
 386          * or less, if the last character is a multi-byte one
 387          *
 388          * @private
 389          * @static
 390          * @method trimToByteLength
 391          * @param {string} s
 392          * @param {number} length
 393          * @return {string}
 394          */
 395         trimToByteLength = function ( s, length ) {
 396                 return mwString.trimByteLength( '', s, length ).newVal;
 397         },
 398
 399         /**
 400          * Cuts a file name to a specific byte length
 401          *
 402          * @private
 403          * @static
 404          * @method trimFileNameToByteLength
 405          * @param {string} name without extension
 406          * @param {string} extension file extension
 407          * @return {string} The full name, including extension
 408          */
 409         trimFileNameToByteLength = function ( name, extension ) {
 410                 // There is a special byte limit for file names and ... remember the dot
 411                 return trimToByteLength( name, FILENAME_MAX_BYTES - extension.length - 1 ) + '.' + extension;
 412         };
 413
 414 /**
 415  * @method constructor
 416  * @param {string} title Title of the page. If no second argument given,
 417  *  this will be searched for a namespace
 418  * @param {number} [namespace=NS_MAIN] If given, will used as default namespace for the given title
 419  * @throws {Error} When the title is invalid
 420  */
 421 function Title( title, namespace ) {
 422         var parsed = parse( title, namespace );
 423         if ( !parsed ) {
 424                 throw new Error( 'Unable to parse title' );
 425         }
 426
 427         this.namespace = parsed.namespace;
 428         this.title = parsed.title;
 429         this.fragment = parsed.fragment;
 430 }
 431
 432 /* Static members */
 433
 434 /**
 435  * Constructor for Title objects with a null return instead of an exception for invalid titles.
 436  *
 437  * Note that `namespace` is the **default** namespace only, and can be overridden by a namespace
 438  * prefix in `title`. If you do not want this behavior, use #makeTitle. See #constructor for
 439  * details.
 440  *
 441  * @static
 442  * @param {string} title
 443  * @param {number} [namespace=NS_MAIN] Default namespace
 444  * @return {mw.Title|null} A valid Title object or null if the title is invalid
 445  */
 446 Title.newFromText = function ( title, namespace ) {
 447         var t, parsed = parse( title, namespace );
 448         if ( !parsed ) {
 449                 return null;
 450         }
 451
 452         t = Object.create( Title.prototype );
 453         t.namespace = parsed.namespace;
 454         t.title = parsed.title;
 455         t.fragment = parsed.fragment;
 456
 457         return t;
 458 };
 459
 460 /**
 461  * Constructor for Title objects with predefined namespace.
 462  *
 463  * Unlike #newFromText or #constructor, this function doesn't allow the given `namespace` to be
 464  * overridden by a namespace prefix in `title`. See #constructor for details about this behavior.
 465  *
 466  * The single exception to this is when `namespace` is 0, indicating the main namespace. The
 467  * function behaves like #newFromText in that case.
 468  *
 469  * @static
 470  * @param {number} namespace Namespace to use for the title
 471  * @param {string} title
 472  * @return {mw.Title|null} A valid Title object or null if the title is invalid
 473  */
 474 Title.makeTitle = function ( namespace, title ) {
 475         return mw.Title.newFromText( getNamespacePrefix( namespace ) + title );
 476 };
 477
 478 /**
 479  * Constructor for Title objects from user input altering that input to
 480  * produce a title that MediaWiki will accept as legal
 481  *
 482  * @static
 483  * @param {string} title
 484  * @param {number|Object} [defaultNamespaceOrOptions=NS_MAIN]
 485  *  If given, will used as default namespace for the given title.
 486  *  This method can also be called with two arguments, in which case
 487  *  this becomes options (see below).
 488  * @param {Object} [options] additional options
 489  * @param {boolean} [options.forUploading=true]
 490  *  Makes sure that a file is uploadable under the title returned.
 491  *  There are pages in the file namespace under which file upload is impossible.
 492  *  Automatically assumed if the title is created in the Media namespace.
 493  * @return {mw.Title|null} A valid Title object or null if the input cannot be turned into a valid title
 494  */
 495 Title.newFromUserInput = function ( title, defaultNamespaceOrOptions, options ) {
 496         var namespace, m, id, ext, lastDot,
 497                 defaultNamespace;
 498
 499         // defaultNamespace is optional; check whether options moves up
 500         if ( arguments.length < 3 && typeof defaultNamespace === 'object' ) {
 501                 options = defaultNamespaceOrOptions;
 502         } else {
 503                 defaultNamespace = defaultNamespaceOrOptions;
 504         }
 505
 506         // merge options into defaults
 507         options = $.extend( {
 508                 forUploading: true
 509         }, options );
 510
 511         namespace = defaultNamespace === undefined ? NS_MAIN : defaultNamespace;
 512
 513         // Normalise additional whitespace
 514         title = title.replace( /\s/g, ' ' ).trim();
 515
 516         // Process initial colon
 517         if ( title !== '' && title[ 0 ] === ':' ) {
 518                 // Initial colon means main namespace instead of specified default
 519                 namespace = NS_MAIN;
 520                 title = title
 521                         // Strip colon
 522                         .substr( 1 )
 523                         // Trim underscores
 524                         .replace( rUnderscoreTrim, '' );
 525         }
 526
 527         // Process namespace prefix (if any)
 528         m = title.match( rSplit );
 529         if ( m ) {
 530                 id = getNsIdByName( m[ 1 ] );
 531                 if ( id !== false ) {
 532                         // Ordinary namespace
 533                         namespace = id;
 534                         title = m[ 2 ];
 535                 }
 536         }
 537
 538         if (
 539                 namespace === NS_MEDIA ||
 540                 ( options.forUploading && ( namespace === NS_FILE ) )
 541         ) {
 542                 title = sanitize( title, [ 'generalRule', 'fileRule' ] );
 543
 544                 // Operate on the file extension
 545                 // Although it is possible having spaces between the name and the ".ext" this isn't nice for
 546                 // operating systems hiding file extensions -> strip them later on
 547                 lastDot = title.lastIndexOf( '.' );
 548
 549                 // No or empty file extension
 550                 if ( lastDot === -1 || lastDot >= title.length - 1 ) {
 551                         return null;
 552                 }
 553
 554                 // Get the last part, which is supposed to be the file extension
 555                 ext = title.slice( lastDot + 1 );
 556
 557                 // Remove whitespace of the name part (that without extension)
 558                 title = title.slice( 0, lastDot ).trim();
 559
 560                 // Cut, if too long and append file extension
 561                 title = trimFileNameToByteLength( title, ext );
 562         } else {
 563                 title = sanitize( title, [ 'generalRule' ] );
 564
 565                 // Cut titles exceeding the TITLE_MAX_BYTES byte size limit
 566                 // (size of underlying database field)
 567                 if ( namespace !== NS_SPECIAL ) {
 568                         title = trimToByteLength( title, TITLE_MAX_BYTES );
 569                 }
 570         }
 571
 572         // Any remaining initial :s are illegal.
 573         title = title.replace( /^:+/, '' );
 574
 575         return Title.newFromText( title, namespace );
 576 };
 577
 578 /**
 579  * Sanitizes a file name as supplied by the user, originating in the user's file system
 580  * so it is most likely a valid MediaWiki title and file name after processing.
 581  * Returns null on fatal errors.
 582  *
 583  * @static
 584  * @param {string} uncleanName The unclean file name including file extension but
 585  *   without namespace
 586  * @return {mw.Title|null} A valid Title object or null if the title is invalid
 587  */
 588 Title.newFromFileName = function ( uncleanName ) {
 589
 590         return Title.newFromUserInput( 'File:' + uncleanName, {
 591                 forUploading: true
 592         } );
 593 };
 594
 595 /**
 596  * Get the file title from an image element
 597  *
 598  *     var title = mw.Title.newFromImg( imageNode );
 599  *
 600  * @static
 601  * @param {HTMLElement|jQuery} img The image to use as a base
 602  * @return {mw.Title|null} The file title or null if unsuccessful
 603  */
 604 Title.newFromImg = function ( img ) {
 605         var matches, i, regex, src, decodedSrc,
 606
 607                 // thumb.php-generated thumbnails
 608                 thumbPhpRegex = /thumb\.php/,
 609                 regexes = [
 610                         // Thumbnails
 611                         /\/[a-f0-9]\/[a-f0-9]{2}\/([^\s/]+)\/[^\s/]+-[^\s/]*$/,
 612
 613                         // Full size images
 614                         /\/[a-f0-9]\/[a-f0-9]{2}\/([^\s/]+)$/,
 615
 616                         // Thumbnails in non-hashed upload directories
 617                         /\/([^\s/]+)\/[^\s/]+-(?:\1|thumbnail)[^\s/]*$/,
 618
 619                         // Full-size images in non-hashed upload directories
 620                         /\/([^\s/]+)$/
 621                 ],
 622
 623                 recount = regexes.length;
 624
 625         src = img.jquery ? img[ 0 ].src : img.src;
 626
 627         matches = src.match( thumbPhpRegex );
 628
 629         if ( matches ) {
 630                 return mw.Title.newFromText( 'File:' + mw.util.getParamValue( 'f', src ) );
 631         }
 632
 633         decodedSrc = decodeURIComponent( src );
 634
 635         for ( i = 0; i < recount; i++ ) {
 636                 regex = regexes[ i ];
 637                 matches = decodedSrc.match( regex );
 638
 639                 if ( matches && matches[ 1 ] ) {
 640                         return mw.Title.newFromText( 'File:' + matches[ 1 ] );
 641                 }
 642         }
 643
 644         return null;
 645 };
 646
 647 /**
 648  * Check if a given namespace is a talk namespace
 649  *
 650  * See MWNamespace::isTalk in PHP
 651  *
 652  * @param {number} namespaceId Namespace ID
 653  * @return {boolean} Namespace is a talk namespace
 654  */
 655 Title.isTalkNamespace = function ( namespaceId ) {
 656         return !!( namespaceId > NS_MAIN && namespaceId % 2 );
 657 };
 658
 659 /**
 660  * Check if signature buttons should be shown in a given namespace
 661  *
 662  * See MWNamespace::wantSignatures in PHP
 663  *
 664  * @param {number} namespaceId Namespace ID
 665  * @return {boolean} Namespace is a signature namespace
 666  */
 667 Title.wantSignaturesNamespace = function ( namespaceId ) {
 668         return Title.isTalkNamespace( namespaceId ) ||
 669                 mw.config.get( 'wgExtraSignatureNamespaces' ).indexOf( namespaceId ) !== -1;
 670 };
 671
 672 /**
 673  * Whether this title exists on the wiki.
 674  *
 675  * @static
 676  * @param {string|mw.Title} title prefixed db-key name (string) or instance of Title
 677  * @return {boolean|null} Boolean if the information is available, otherwise null
 678  * @throws {Error} If title is not a string or mw.Title
 679  */
 680 Title.exists = function ( title ) {
 681         var match,
 682                 obj = Title.exist.pages;
 683
 684         if ( typeof title === 'string' ) {
 685                 match = obj[ title ];
 686         } else if ( title instanceof Title ) {
 687                 match = obj[ title.toString() ];
 688         } else {
 689                 throw new Error( 'mw.Title.exists: title must be a string or an instance of Title' );
 690         }
 691
 692         if ( typeof match !== 'boolean' ) {
 693                 return null;
 694         }
 695
 696         return match;
 697 };
 698
 699 /**
 700  * Store page existence
 701  *
 702  * @static
 703  * @property {Object} exist
 704  * @property {Object} exist.pages Keyed by title. Boolean true value indicates page does exist.
 705  *
 706  * @property {Function} exist.set The setter function.
 707  *
 708  *  Example to declare existing titles:
 709  *
 710  *     Title.exist.set( ['User:John_Doe', ...] );
 711  *
 712  *  Example to declare titles nonexistent:
 713  *
 714  *     Title.exist.set( ['File:Foo_bar.jpg', ...], false );
 715  *
 716  * @property {string|Array} exist.set.titles Title(s) in strict prefixedDb title form
 717  * @property {boolean} [exist.set.state=true] State of the given titles
 718  * @return {boolean}
 719  */
 720 Title.exist = {
 721         pages: {},
 722
 723         set: function ( titles, state ) {
 724                 var i, len,
 725                         pages = this.pages;
 726
 727                 titles = Array.isArray( titles ) ? titles : [ titles ];
 728                 state = state === undefined ? true : !!state;
 729
 730                 for ( i = 0, len = titles.length; i < len; i++ ) {
 731                         pages[ titles[ i ] ] = state;
 732                 }
 733                 return true;
 734         }
 735 };
 736
 737 /**
 738  * Normalize a file extension to the common form, making it lowercase and checking some synonyms,
 739  * and ensure it's clean. Extensions with non-alphanumeric characters will be discarded.
 740  * Keep in sync with File::normalizeExtension() in PHP.
 741  *
 742  * @param {string} extension File extension (without the leading dot)
 743  * @return {string} File extension in canonical form
 744  */
 745 Title.normalizeExtension = function ( extension ) {
 746         var
 747                 lower = extension.toLowerCase(),
 748                 squish = {
 749                         htm: 'html',
 750                         jpeg: 'jpg',
 751                         mpeg: 'mpg',
 752                         tiff: 'tif',
 753                         ogv: 'ogg'
 754                 };
 755         if ( Object.prototype.hasOwnProperty.call( squish, lower ) ) {
 756                 return squish[ lower ];
 757         } else if ( /^[0-9a-z]+$/.test( lower ) ) {
 758                 return lower;
 759         } else {
 760                 return '';
 761         }
 762 };
 763
 764 /**
 765  * PHP's strtoupper differs from String.toUpperCase in a number of cases (T147646).
 766  *
 767  * @param {string} chr Unicode character
 768  * @return {string} Unicode character, in upper case, according to the same rules as in PHP
 769  */
 770 Title.phpCharToUpper = function ( chr ) {
 771         var mapped = toUpperMapping[ chr ];
 772         return mapped || chr.toUpperCase();
 773 };
 774
 775 /* Public members */
 776
 777 Title.prototype = {
 778         constructor: Title,
 779
 780         /**
 781          * Get the namespace number
 782          *
 783          * Example: 6 for "File:Example_image.svg".
 784          *
 785          * @return {number}
 786          */
 787         getNamespaceId: function () {
 788                 return this.namespace;
 789         },
 790
 791         /**
 792          * Get the namespace prefix (in the content language)
 793          *
 794          * Example: "File:" for "File:Example_image.svg".
 795          * In #NS_MAIN this is '', otherwise namespace name plus ':'
 796          *
 797          * @return {string}
 798          */
 799         getNamespacePrefix: function () {
 800                 return getNamespacePrefix( this.namespace );
 801         },
 802
 803         /**
 804          * Get the page name without extension or namespace prefix
 805          *
 806          * Example: "Example_image" for "File:Example_image.svg".
 807          *
 808          * For the page title (full page name without namespace prefix), see #getMain.
 809          *
 810          * @return {string}
 811          */
 812         getName: function () {
 813                 var ext = this.getExtension();
 814                 if ( ext === null ) {
 815                         return this.getMain();
 816                 }
 817                 return this.getMain().slice( 0, -ext.length - 1 );
 818         },
 819
 820         /**
 821          * Get the page name (transformed by #text)
 822          *
 823          * Example: "Example image" for "File:Example_image.svg".
 824          *
 825          * For the page title (full page name without namespace prefix), see #getMainText.
 826          *
 827          * @return {string}
 828          */
 829         getNameText: function () {
 830                 return text( this.getName() );
 831         },
 832
 833         /**
 834          * Get the extension of the page name (if any)
 835          *
 836          * @return {string|null} Name extension or null if there is none
 837          */
 838         getExtension: function () {
 839                 var lastDot = this.title.lastIndexOf( '.' );
 840                 if ( lastDot === -1 ) {
 841                         return null;
 842                 }
 843                 return this.title.slice( lastDot + 1 ) || null;
 844         },
 845
 846         /**
 847          * Shortcut for appendable string to form the main page name.
 848          *
 849          * Returns a string like ".json", or "" if no extension.
 850          *
 851          * @return {string}
 852          */
 853         getDotExtension: function () {
 854                 var ext = this.getExtension();
 855                 return ext === null ? '' : '.' + ext;
 856         },
 857
 858         /**
 859          * Get the main page name
 860          *
 861          * Example: "Example_image.svg" for "File:Example_image.svg".
 862          *
 863          * @return {string}
 864          */
 865         getMain: function () {
 866                 if (
 867                         mw.config.get( 'wgCaseSensitiveNamespaces' ).indexOf( this.namespace ) !== -1 ||
 868                         !this.title.length
 869                 ) {
 870                         return this.title;
 871                 }
 872                 return mw.Title.phpCharToUpper( this.title[ 0 ] ) + this.title.slice( 1 );
 873         },
 874
 875         /**
 876          * Get the main page name (transformed by #text)
 877          *
 878          * Example: "Example image.svg" for "File:Example_image.svg".
 879          *
 880          * @return {string}
 881          */
 882         getMainText: function () {
 883                 return text( this.getMain() );
 884         },
 885
 886         /**
 887          * Get the full page name
 888          *
 889          * Example: "File:Example_image.svg".
 890          * Most useful for API calls, anything that must identify the "title".
 891          *
 892          * @return {string}
 893          */
 894         getPrefixedDb: function () {
 895                 return this.getNamespacePrefix() + this.getMain();
 896         },
 897
 898         /**
 899          * Get the full page name (transformed by #text)
 900          *
 901          * Example: "File:Example image.svg" for "File:Example_image.svg".
 902          *
 903          * @return {string}
 904          */
 905         getPrefixedText: function () {
 906                 return text( this.getPrefixedDb() );
 907         },
 908
 909         /**
 910          * Get the page name relative to a namespace
 911          *
 912          * Example:
 913          *
 914          * - "Foo:Bar" relative to the Foo namespace becomes "Bar".
 915          * - "Bar" relative to any non-main namespace becomes ":Bar".
 916          * - "Foo:Bar" relative to any namespace other than Foo stays "Foo:Bar".
 917          *
 918          * @param {number} namespace The namespace to be relative to
 919          * @return {string}
 920          */
 921         getRelativeText: function ( namespace ) {
 922                 if ( this.getNamespaceId() === namespace ) {
 923                         return this.getMainText();
 924                 } else if ( this.getNamespaceId() === NS_MAIN ) {
 925                         return ':' + this.getPrefixedText();
 926                 } else {
 927                         return this.getPrefixedText();
 928                 }
 929         },
 930
 931         /**
 932          * Get the fragment (if any).
 933          *
 934          * Note that this method (by design) does not include the hash character and
 935          * the value is not url encoded.
 936          *
 937          * @return {string|null}
 938          */
 939         getFragment: function () {
 940                 return this.fragment;
 941         },
 942
 943         /**
 944          * Get the URL to this title
 945          *
 946          * @see mw.util#getUrl
 947          * @param {Object} [params] A mapping of query parameter names to values,
 948          *     e.g. `{ action: 'edit' }`.
 949          * @return {string}
 950          */
 951         getUrl: function ( params ) {
 952                 var fragment = this.getFragment();
 953                 if ( fragment ) {
 954                         return mw.util.getUrl( this.toString() + '#' + fragment, params );
 955                 } else {
 956                         return mw.util.getUrl( this.toString(), params );
 957                 }
 958         },
 959
 960         /**
 961          * Check if the title is in a talk namespace
 962          *
 963          * @return {boolean} The title is in a talk namespace
 964          */
 965         isTalkPage: function () {
 966                 return Title.isTalkNamespace( this.getNamespaceId() );
 967         },
 968
 969         /**
 970          * Get the title for the associated talk page
 971          *
 972          * @return {mw.Title|null} The title for the associated talk page, null if not available
 973          */
 974         getTalkPage: function () {
 975                 if ( !this.canHaveTalkPage() ) {
 976                         return null;
 977                 }
 978                 return this.isTalkPage() ?
 979                         this :
 980                         Title.makeTitle( this.getNamespaceId() + 1, this.getMainText() );
 981         },
 982
 983         /**
 984          * Get the title for the subject page of a talk page
 985          *
 986          * @return {mw.Title|null} The title for the subject page of a talk page, null if not available
 987          */
 988         getSubjectPage: function () {
 989                 return this.isTalkPage() ?
 990                         Title.makeTitle( this.getNamespaceId() - 1, this.getMainText() ) :
 991                         this;
 992         },
 993
 994         /**
 995          * Check the the title can have an associated talk page
 996          *
 997          * @return {boolean} The title can have an associated talk page
 998          */
 999         canHaveTalkPage: function () {
1000                 return this.getNamespaceId() >= NS_MAIN;
1001         },
1002
1003         /**
1004          * Whether this title exists on the wiki.
1005          *
1006          * @see #static-method-exists
1007          * @return {boolean|null} Boolean if the information is available, otherwise null
1008          */
1009         exists: function () {
1010                 return Title.exists( this );
1011         }
1012 };
1013
1014 /**
1015  * @alias #getPrefixedDb
1016  * @method
1017  */
1018 Title.prototype.toString = Title.prototype.getPrefixedDb;
1019
1020 /**
1021  * @alias #getPrefixedText
1022  * @method
1023  */
1024 Title.prototype.toText = Title.prototype.getPrefixedText;
1025
1026 // Expose
1027 mw.Title = Title;