ECMAScript Internationalization API Specification · Internationalization API Specification . ... 12.1.1 InitializeDateTimeFormat ... The 1st Edition API was developed by an ad-hoc

Reference number ECMA-123:2009

© Ecma International 2009

ECMA-402 4th Edition / June 2017

ECMAScript® 2017

Internationalization API Specification

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© Ecma International 2017

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Copyright © 2017 Ecma International Ecma International Rue du Rhone 114 CH-1204 Geneva Tel: +41 22 849 6000 Fax: +41 22 849 6001 Web: http://www.ecma-international.org This document and possible translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published, and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this section are included on all such copies and derivative works. However, this document itself may not be modified in any way, including by removing the copyright notice or references to Ecma International, except as needed for the purpose of developing any document or deliverable produced by Ecma International (in which case the rules applied to copyrights must be followed) or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by Ecma International or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and ECMA INTERNATIONAL DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY OWNERSHIP RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." Software License All Software contained in this document ("Software)" is protected by copyright and is being made available under the "BSD License", included below. This Software may be subject to third party rights (rights from parties other than Ecma International), including patent rights, and no licenses under such third party rights are granted under this license even if the third party concerned is a member of Ecma International. SEE THE ECMA CODE OF CONDUCT IN PATENT MATTERS AVAILABLE AT http://www.ecma-international.org/memento/codeofconduct.htm FOR INFORMATION REGARDING THE LICENSING OF PATENT CLAIMS THAT ARE REQUIRED TO IMPLEMENT ECMA INTERNATIONAL STANDARDS*. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the authors nor Ecma International may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE ECMA INTERNATIONAL "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ECMA INTERNATIONAL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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ii © Ecma International 2017

Introduction1Scope2Conformance3NormativeReferences4Overview4.1Internationalization,Localization,andGlobalization4.2APIOverview4.3ImplementationDependencies

5NotationalConventions5.1Well-KnownIntrinsicObjects

6IdentiLicationofLocales,Currencies,andTimeZones6.1CaseSensitivityandCaseMapping6.2LanguageTags6.2.1UnicodeLocaleExtensionSequences6.2.2IsStructurallyValidLanguageTag(locale)6.2.3CanonicalizeLanguageTag(locale)6.2.4DefaultLocale()

6.3CurrencyCodes6.3.1IsWellFormedCurrencyCode(currency)

6.4TimeZoneNames

ECMAScript®2017InternationalizationAPISpeci9ication

TableofContents

6.4.1IsValidTimeZoneName(timeZone)6.4.2CanonicalizeTimeZoneName6.4.3DefaultTimeZone()

7RequirementsforStandardBuilt-inECMAScriptObjects8TheIntlObject8.1ConstructorPropertiesoftheIntlObject8.1.1Intl.Collator(...)8.1.2Intl.NumberFormat(...)8.1.3Intl.DateTimeFormat(...)

8.2FunctionPropertiesoftheIntlObject8.2.1Intl.getCanonicalLocales(locales)

9LocaleandParameterNegotiation9.1InternalslotsofServiceConstructors9.2AbstractOperations9.2.1CanonicalizeLocaleList(locales)9.2.2BestAvailableLocale(availableLocales,locale)9.2.3LookupMatcher(availableLocales,requestedLocales)9.2.4BestFitMatcher(availableLocales,requestedLocales)9.2.5UnicodeExtensionSubtags(extension)9.2.6ResolveLocale(availableLocales,requestedLocales,options,relevantExtensionKeys,localeData)9.2.7LookupSupportedLocales(availableLocales,requestedLocales)9.2.8BestFitSupportedLocales(availableLocales,requestedLocales)9.2.9SupportedLocales(availableLocales,requestedLocales,options)9.2.10GetOption(options,property,type,values,fallback)9.2.11GetNumberOption(options,property,minimum,maximum,fallback)

10CollatorObjects10.1TheIntl.CollatorConstructor10.1.1InitializeCollator(collator,locales,options)

10.1.2Intl.Collator([locales[,options]])10.2PropertiesoftheIntl.CollatorConstructor10.2.1Intl.Collator.prototype10.2.2Intl.Collator.supportedLocalesOf(locales[,options])10.2.3InternalSlots

10.3PropertiesoftheIntl.CollatorPrototypeObject10.3.1Intl.Collator.prototype.constructor10.3.2Intl.Collator.prototype[@@toStringTag]10.3.3getIntl.Collator.prototype.compare10.3.4CollatorCompareFunctions10.3.5Intl.Collator.prototype.resolvedOptions()

10.4PropertiesofIntl.CollatorInstances11NumberFormatObjects11.1AbstractOperationsForNumberFormatObjects11.1.1SetNumberFormatDigitOptions(intlObj,options,mnfdDefault)11.1.2InitializeNumberFormat(numberFormat,locales,options)11.1.3CurrencyDigits(currency)11.1.4NumberFormatFunctions11.1.5FormatNumberToString(numberFormat,x)11.1.6PartitionNumberPattern(numberFormat,x)11.1.7FormatNumber(numberFormat,x)11.1.8FormatNumberToParts(numberFormat,x)11.1.9ToRawPrecision(x,minPrecision,maxPrecision)11.1.10ToRawFixed(x,minInteger,minFraction,maxFraction)11.1.11UnwrapNumberFormat(nf)

11.2TheIntl.NumberFormatConstructor11.2.1Intl.NumberFormat([locales[,options]])

11.3PropertiesoftheIntl.NumberFormatConstructor11.3.1Intl.NumberFormat.prototype11.3.2Intl.NumberFormat.supportedLocalesOf(locales[,options])

11.3.3Internalslots11.4PropertiesoftheIntl.NumberFormatPrototypeObject11.4.1Intl.NumberFormat.prototype.constructor11.4.2Intl.NumberFormat.prototype[@@toStringTag]11.4.3getIntl.NumberFormat.prototype.format11.4.4Intl.NumberFormat.prototype.resolvedOptions()

11.5PropertiesofIntl.NumberFormatInstances12DateTimeFormatObjects12.1AbstractOperationsForDateTimeFormatObjects12.1.1InitializeDateTimeFormat(dateTimeFormat,locales,options)12.1.2ToDateTimeOptions(options,required,defaults)12.1.3BasicFormatMatcher(options,formats)12.1.4BestFitFormatMatcher(options,formats)12.1.5DateTimeFormatFunctions12.1.6PartitionDateTimePattern(dateTimeFormat,x)12.1.7FormatDateTime(dateTimeFormat,x)12.1.8FormatDateTimeToParts(dateTimeFormat,x)12.1.9ToLocalTime(date,calendar,timeZone)12.1.10UnwrapDateTimeFormat(dtf)

13TheIntl.DateTimeFormatConstructor13.1Intl.DateTimeFormat([locales[,options]])

14PropertiesoftheIntl.DateTimeFormatConstructor14.1Intl.DateTimeFormat.prototype14.2Intl.DateTimeFormat.supportedLocalesOf(locales[,options])14.3Internalslots

15PropertiesoftheIntl.DateTimeFormatPrototypeObject15.1Intl.DateTimeFormat.prototype.constructor15.2Intl.DateTimeFormat.prototype[@@toStringTag]15.3getIntl.DateTimeFormat.prototype.format15.4Intl.DateTimeFormat.prototype.formatToParts([date])15.5Intl.DateTimeFormat.prototype.resolvedOptions()

16PropertiesofIntl.DateTimeFormatInstances17LocaleSensitiveFunctionsoftheECMAScriptLanguageSpeciLication17.1PropertiesoftheStringPrototypeObject17.1.1String.prototype.localeCompare(that[,locales[,options]])17.1.2String.prototype.toLocaleLowerCase([locales])17.1.3String.prototype.toLocaleUpperCase([locales])

17.2PropertiesoftheNumberPrototypeObject17.2.1Number.prototype.toLocaleString([locales[,options]])

17.3PropertiesoftheDatePrototypeObject17.3.1Date.prototype.toLocaleString([locales[,options]])17.3.2Date.prototype.toLocaleDateString([locales[,options]])17.3.3Date.prototype.toLocaleTimeString([locales[,options]])

17.4PropertiesoftheArrayPrototypeObject17.4.1Array.prototype.toLocaleString([locales[,options]])

AImplementationDependentBehaviourBAdditionsandChangesThatIntroduceIncompatibilitieswithPriorEditionsCCopyright&SoftwareLicense

ThisspeciLication'ssourcecanbefoundathttps://github.com/tc39/ecma402.

TheECMAScript2017InternationalizationAPISpeciLication(ECMA-4024thEdition),provideskeylanguagesensitivefunctionalityasacomplementtotheECMAScript2017LanguageSpeciLication(ECMA-

Introduction

https://github.com/tc39/ecma402

2628thEditionorsuccessor).Itsfunctionalityhasbeenselectedfromthatofwell-establishedinternationalizationAPIssuchasthoseoftheInternationalizationComponentsforUnicode(ICU)library,ofthe.NETframework,oroftheJavaplatform.

The1stEditionAPIwasdevelopedbyanad-hocgroupestablishedbyEcmaTC39inSeptember2010basedonaproposalbyNebojšaĆirićandJungshikShin.

Internationalizationofsoftwareisnevercomplete.WeexpectsigniLicantenhancementsinfutureeditionsofthisspeciLication.

Editor,4rdEditionCaridyPatiño

ContributorsZibiBranieckiDanielEhrenberg

Editor,3rdEditionCaridyPatiño

ContributorsRickWaldronAndréBargullEricFerraiuoloStevenR.LoomisZibiBraniecki

Editor,2ndEditionRickWaldron

ContributorsNorbertLindenbergAllenWirfs-BrockAndréBargullStevenR.Loomis

Editor,1stEditionNorbertLindenberg

ContributorsEricAlbrightNebojšaĆirićPeterConstableMarkDavisRichardGillamStevenLoomisMihaiNitaAddisonPhillipsRoozbehPournaderJungshikShinShawnSteeleAllenWirfs-Brock

FeedbackandReviewfromErikArvidssonJohnJ.BartonZbigniewBranieckiMarcosCáceresBrendanEichJohnEmmonsGordonP.HemsleyDavidHermanLukeHobanOliverHuntSureshJayabalanYehudaKatzMarkS.MillerAndrewPaprockiAdamPellerAxelRauschmayerAndreasRossberg

AlexRussellMarkusSchererDmitrySoshnikovYusukeSuzukiJohnTamplinRickWaldronAntonYatsenkoNicholasZakas

ThisStandarddeLinestheapplicationprogramminginterfaceforECMAScriptobjectsthatsupportprogramsthatneedtoadapttothelinguisticandculturalconventionsusedbydifferenthumanlanguagesandcountries.

AconformingimplementationoftheECMAScript2017InternationalizationAPISpeciLicationmustconformtotheECMAScript2017LanguageSpeciLication(ECMA-2628thEdition,orsuccessor),andmustprovideandsupportalltheobjects,properties,functions,andprogramsemanticsdescribedinthisspeciLication.

AconformingimplementationoftheECMAScript2017InternationalizationAPISpeciLicationispermittedtoprovideadditionalobjects,properties,andfunctionsbeyondthosedescribedinthisspeciLication.Inparticular,aconformingimplementationoftheECMAScript2017InternationalizationAPISpeciLicationis

1 Scope

2 Conformance

permittedtoprovidepropertiesnotdescribedinthisspeciLication,andvaluesforthoseproperties,forobjectsthataredescribedinthisspeciLication.AconformingimplementationisnotpermittedtoaddoptionalargumentstothefunctionsdeLinedinthisspeciLication.

Aconformingimplementationispermittedtoacceptadditionalvalues,andthenhaveimplementation-deLinedbehaviourinsteadofthrowingaRangeError,forthefollowingpropertiesofoptionsarguments:

TheoptionspropertylocaleMatcherinallconstructorsandsupportedLocalesOfmethods.TheoptionspropertiesusageandsensitivityintheCollatorconstructor.TheoptionspropertiesstyleandcurrencyDisplayintheNumberFormatconstructor.TheoptionspropertiesminimumIntegerDigits,minimumFractionDigits,maximumFractionDigits,minimumSigniLicantDigits,andmaximumSigniLicantDigitsintheNumberFormatconstructor,providedthattheadditionalvaluesareinterpretedasintegervalueshigherthanthespeciLiedlimits.TheoptionspropertieslistedinTable4intheDateTimeFormatconstructor.TheoptionspropertyformatMatcherintheDateTimeFormatconstructor.

Thefollowingreferenceddocumentsarerequiredfortheapplicationofthisdocument.Fordatedreferences,onlytheeditioncitedapplies.Forundatedreferences,thelatesteditionofthereferenced

3 NormativeReferences

document(includinganyamendments)applies.

ECMAScript2017LanguageSpeciLication(ECMA-2628thEdition,orsuccessor).http://www.ecma-international.org/publications/standards/Ecma-262.htm

NOTE Throughoutthisdocument,thephrase"ES2017,x"(wherexisasequenceofnumbersseparatedbyperiods)maybeusedasshorthandfor"ECMAScript2017LanguageSpeciLication(ECMA-2628thEdition,subclausex)".

ISO/IEC10646:2014:InformationTechnology–UniversalMultiple-OctetCodedCharacterSet(UCS)plusAmendment1:2015andAmendment2,plusadditionalamendmentsandcorrigenda,orsuccessor

http://www.iso.org/iso/catalogue_detail.htm?csnumber=63182http://www.iso.org/iso/catalogue_detail.htm?csnumber=65047http://www.iso.org/iso/catalogue_detail.htm?csnumber=66791

ISO4217:2015,Codesfortherepresentationofcurrenciesandfunds,orsuccessorIETFBCP47:

RFC5646,TagsforIdentifyingLanguages,orsuccessorRFC4647,MatchingofLanguageTags,orsuccessor

IETFRFC6067,BCP47ExtensionU,orsuccessorIANATimeZoneDatabaseTheUnicodeStandardUnicodeTechnicalStandard35,UnicodeLocaleDataMarkupLanguage

http://www.ecma-international.org/publications/standards/Ecma-262.htm

http://www.iso.org/iso/catalogue_detail.htm?csnumber=63182



http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=64758

http://tools.ietf.org/html/rfc5646



http://www.iana.org/time-zones/

http://www.unicode.org/versions/latest

http://www.unicode.org/reports/tr35/

Thissectioncontainsanon-normativeoverviewoftheECMAScript2017InternationalizationAPISpeciLication.

Internationalizationofsoftwaremeansdesigningitsuchthatitsupportsorcanbeeasilyadaptedtosupporttheneedsofusersspeakingdifferentlanguagesandhavingdifferentculturalexpectations,andenablesworldwidecommunicationbetweenthem.LocalizationthenistheactualadaptationtoaspeciLiclanguageandculture.Globalizationofsoftwareiscommonlyunderstoodtobethecombinationofinternationalizationandlocalization.Globalizationstartsatthelowestlevelbyusingatextrepresentationthatsupportsalllanguagesintheworld,andusingstandardidentiLierstoidentifylanguages,countries,timezones,andotherrelevantparameters.Itcontinueswithusingauserinterfacelanguageanddatapresentationthattheuserunderstands,andLinallyoftenrequiresproduct-speciLicadaptationstotheuser’slanguage,culture,andenvironment.

TheECMAScript2017LanguageSpeciLicationlaysthefoundationbyusingUnicodefortextrepresentationandbyprovidingafewlanguage-sensitivefunctions,butgivesapplicationslittlecontroloverthebehaviourofthesefunctions.TheECMAScript2017InternationalizationAPISpeciLicationbuildsonthisbyprovidingasetofcustomizablelanguage-sensitivefunctionality.TheAPIisusefulevenforapplicationsthatthemselvesarenotinternationalized,asevenapplicationstargetingonlyonelanguageandoneregionneedtoproperlysupportthatonelanguageandregion.However,theAPIalsoenablesapplicationsthatsupportmultiplelanguagesand

4 Overview

4.1 Internationalization,Localization,andGlobalization

regions,evenconcurrently,asmaybeneededinserverenvironments.

TheECMAScript2017InternationalizationAPISpeciLicationisdesignedtocomplementtheECMAScript2017LanguageSpeciLicationbyprovidingkeylanguage-sensitivefunctionality.TheAPIcanbeaddedtoanimplementationoftheECMAScript2017LanguageSpeciLication(ECMA-2628thEdition,orsuccessor).

TheECMAScript2017InternationalizationAPISpeciLicationprovidesseveralkeypiecesoflanguage-sensitivefunctionalitythatarerequiredinmostapplications:Stringcomparison(collation),numberformatting,dateandtimeformatting,andcaseconversion.WhiletheECMAScript2017LanguageSpeciLicationprovidesfunctionsforthisbasicfunctionality(onArray.prototype:toLocaleString;onString.prototype:localeCompare,toLocaleLowerCase,toLocaleUpperCase;onNumber.prototype:toLocaleString;onDate.prototype:toLocaleString,toLocaleDateString,andtoLocaleTimeString),itleavestheactualbehaviourofthesefunctionslargelyuptoimplementationstodeLine.TheECMAScript2017InternationalizationAPISpeciLicationprovidesadditionalfunctionality,controloverthelanguageandoverdetailsofthebehaviourtobeused,andamorecompletespeciLicationofrequiredfunctionality.

ApplicationscanusetheAPIintwoways:

1. Directly,byusingtheconstructorsIntl.Collator,Intl.NumberFormat,orIntl.DateTimeFormattoconstructanobject,specifyingalistofpreferredlanguagesandoptionstoconLigurethebehaviouroftheresultingobject.Theobjectthen

4.2 APIOverview

providesamainfunction(compareorformat),whichcanbecalledrepeatedly.ItalsoprovidesaresolvedOptionsfunction,whichtheapplicationcanusetoLindouttheexactconLigurationoftheobject.

2. Indirectly,byusingthefunctionsoftheECMAScript2017LanguageSpeciLicationmentionedabove.ThecollationandformattingfunctionsarerespeciLiedinthisspeciLicationtoacceptthesameargumentsastheCollator,NumberFormat,andDateTimeFormatconstructorsandproducethesameresultsastheircompareorformatmethods.ThecaseconversionfunctionsarerespeciLiedtoacceptalistofpreferredlanguages.

TheIntlobjectisusedtopackageallfunctionalitydeLinedintheECMAScript2017InternationalizationAPISpeciLicationtoavoidnamecollisions.

Duetothenatureofinternationalization,theAPIspeciLicationhastoleaveseveraldetailsimplementationdependent:

Thesetoflocalesthatanimplementationsupportswithadequatelocalizations:Linguistsestimatethenumberofhumanlanguagestoaround6000,andthemorewidelyspokenoneshavevariationsbasedonregionsorotherparameters.Evenlargelocaledatacollections,suchastheCommonLocaleDataRepository,coveronlyasubsetofthislargeset.Implementationstargetingresource-constraineddevicesmayhavetofurtherreducethesubset.Theexactformoflocalizationssuchasformatpatterns:Inmanycaseslocale-dependentconventionsarenotstandardized,sodifferentformsmayexistsidebyside,ortheyvaryovertime.Differentinternationalizationlibrariesmayhaveimplemented

4.3 ImplementationDependencies

differentforms,withoutanyofthembeingactuallywrong.InordertoallowthisAPItobeimplementedontopofexistinglibraries,suchvariationshavetobepermitted.SubsetsofUnicode:Someoperations,suchascollation,operateonstringsthatcanincludecharactersfromtheentireUnicodecharacterset.However,boththeUnicodestandardandtheECMAScriptstandardallowimplementationstolimittheirfunctionalitytosubsetsoftheUnicodecharacterset.Inaddition,localeconventionstypicallydon’tspecifythedesiredbehaviourfortheentireUnicodecharacterset,butonlyforthosecharactersthatarerelevantforthelocale.WhiletheUnicodeCollationAlgorithmcombinesadefaultcollationorderfortheentireUnicodecharactersetwiththeabilitytotailorforlocalconventions,subsetsandtailoringsstillresultindifferencesinbehaviour.

ThisstandardusesasubsetofthenotationalconventionsoftheECMAScript2017LanguageSpeciLication(ECMA-2628thEdition),asES2017:

ObjectInternalMethodsandInternalSlots,asdescribedinES2017,6.1.7.2.Algorithmconventions,includingtheuseofabstractoperations,asdescribedinES2017,7.1,7.2,7.3.InternalSlots,asdescribedinES2017,9.1.TheListandRecordSpeciLicationType,asdescribedinES2017,6.2.1.

NOTE AsdescribedintheECMAScriptLanguageSpeciLication,algorithmsareusedtopreciselyspecify

5 NotationalConventions

https://tc39.github.io/ecma262/#sec-object-internal-methods-and-internal-slots

https://tc39.github.io/ecma262/#sec-type-conversion

https://tc39.github.io/ecma262/#sec-testing-and-comparison-operations

https://tc39.github.io/ecma262/#sec-operations-on-objects

https://tc39.github.io/ecma262/#sec-ordinary-object-internal-methods-and-internal-slots

https://tc39.github.io/ecma262/#sec-list-and-record-specification-type



therequiredsemanticsofECMAScriptconstructs,butarenotintendedtoimplytheuseofanyspeciLicimplementationtechnique.InternalslotsareusedtodeLinethesemanticsofobjectvalues,butarenotpartoftheAPI.TheyaredeLinedpurelyforexpositorypurposes.AnimplementationoftheAPImustbehaveasifitproducedandoperateduponinternalslotsinthemannerdescribedhere.

AsanextensiontotheRecordSpeciLicationType,thenotation"[[<name>]]"denotesaLieldwhosenameisgivenbythevariablename,whichmusthaveaStringvalue.Forexample,ifavariableshasthevalue"a",then[[<s>]]denotestheLield[[<a>]].

ForECMAScriptobjects,thisstandardmayusevariable-namedinternalslots:Thenotation"[[<name>]]"denotesaninternalslotwhosenameisgivenbythevariablename,whichmusthaveaStringvalue.Forexample,ifavariableshasthevalue"a",then[[<s>]]denotesthe[[<a>]]internalslot.

ThisspeciLicationusesblocksdemarcatedas NORMATIVEOPTIONALtodenotethesenseofAnnexBinECMA262.Thatis,normativeoptionalsectionsarerequiredwhentheECMAScripthostisawebbrowser.ThecontentofthesectionisnormativebutoptionaliftheECMAScripthostisnotawebbrowser.

ThefollowingtableextendstheWell-KnownIntrinsicObjectstabledeLinedinES2017,6.1.7.4.

Table1:Well-knownIntrinsicObjects(Extensions)

IntrinsicName GlobalName ECMAScriptLanguage

5.1 Well-KnownIntrinsicObjects


https://tc39.github.io/ecma262/#sec-additional-ecmascript-features-for-web-browsers

https://tc39.github.io/ecma262/#sec-well-known-intrinsic-objects

Association

%Date_now% Date.now Theinitialvalueofthenowdatapropertyoftheintrinsic(ES2017,

%Intl% Intl TheIntl

%Collator% Intl.Collator TheIntl.Collatorconstructor(

%CollatorPrototype% Intl.Collator.prototype Theinitialvalueoftheprototype

propertyoftheintrinsic%Collator%

%NumberFormat% Intl.NumberFormat TheIntl.NumberFormat

constructor(

%NumberFormatPrototype% Intl.NumberFormat.prototype Theinitialvalueoftheprototype

propertyoftheintrinsic%NumberFormat%(11.3.1).

%DateTimeFormat% Intl.DateTimeFormat TheIntl.DateTimeFormat

constructor(

%DateTimeFormatPrototype% Intl.DateTimeFormat.prototype Theinitialvalueoftheprototype

propertyoftheintrinsic%DateTimeFormat%(14.1).

%StringProto_includes% String.prototype.includes Theinitialvalueoftheincludes

propertyoftheintrinsic%StringPrototype%(ES2017,

%StringProto_indexOf% String.prototype.indexOf TheinitialvalueoftheindexOf

oftheintrinsic%StringPrototype%(ES2017,

%ArrayProto_indexOf% Array.prototype.indexOf TheinitialvalueoftheindexOf

oftheintrinsic%ArrayPrototype%(ES2017,

ThisclausedescribestheStringvaluesusedintheECMAScript2017InternationalizationAPISpeciLicationtoidentifylocales,currencies,andtimezones.

TheStringvaluesusedtoidentifylocales,currencies,andtimezonesareinterpretedinacase-insensitivemanner,treatingtheUnicode

6 Identi9icationofLocales,Currencies,andTimeZones

6.1 CaseSensitivityandCaseMapping

https://tc39.github.io/ecma262/#sec-properties-of-the-string-prototype-object

https://tc39.github.io/ecma262/#sec-properties-of-the-string-prototype-object

https://tc39.github.io/ecma262/#sec-properties-of-the-array-prototype-object

BasicLatincharacters"A"to"Z"(U+0041toU+005A)asequivalenttothecorrespondingBasicLatincharacters"a"to"z"(U+0061toU+007A).Noothercasefoldingequivalencesareapplied.Whenmappingtouppercase,amappingshallbeusedthatmapscharactersintherange"a"to"z"(U+0061toU+007A)tothecorrespondingcharactersintherange"A"to"Z"(U+0041toU+005A)andmapsnoothercharacterstothelatterrange.

EXAMPLES"ß"(U+00DF)mustnotmatchorbemappedto"SS"(U+0053,U+0053)."ı"(U+0131)mustnotmatchorbemappedto"I"(U+0049).

TheECMAScript2017InternationalizationAPISpeciLicationidentiLieslocalesusinglanguagetagsasdeLinedbyIETFBCP47(RFCs5646and4647ortheirsuccessors),whichmayincludeextensionssuchasthoseregisteredthroughRFC6067.TheircanonicalformisspeciLiedinRFC5646section4.5oritssuccessor.

BCP47languagetagsthatmeetthosevaliditycriteriaofRFC5646section2.2.9thatcanbeveriLiedwithoutreferencetotheIANALanguageSubtagRegistryareconsideredstructurallyvalid.AllstructurallyvalidlanguagetagsarevalidforusewiththeAPIsdeLinedbythisstandard.However,thesetoflocalesandthuslanguagetagsthatanimplementationsupportswithadequatelocalizationsisimplementationdependent.TheconstructorsCollator,NumberFormat,andDateTimeFormatmapthelanguagetagsusedinrequeststolocalessupportedbytheirrespectiveimplementations.

6.2 LanguageTags

6.2.1 UnicodeLocaleExtensionSequences

Thisstandardusestheterm"Unicodelocaleextensionsequence"foranysubstringofalanguagetagthatisnotpartofaprivateusesubtagsequence,startswithaseparator"-"andthesingleton"u",andincludesthemaximumsequenceoffollowingnon-singletonsubtagsandtheirpreceding"-"separators.

TheIsStructurallyValidLanguageTagabstractoperationveriLiesthatthelocaleargument(whichmustbeaStringvalue)

representsawell-formedBCP47languagetagasspeciLiedinRFC5646section2.1,orsuccessor,doesnotincludeduplicatevariantsubtags,anddoesnotincludeduplicatesingletonsubtags.

TheabstractoperationreturnstrueiflocalecanbegeneratedfromtheABNFgrammarinsection2.1oftheRFC,startingwithLanguage-Tag,anddoesnotcontainduplicatevariantorsingletonsubtags(otherthanasaprivateusesubtag).Itreturnsfalseotherwise.TerminalvaluecharactersinthegrammarareinterpretedastheUnicodeequivalentsoftheASCIIoctetvaluesgiven.

TheCanonicalizeLanguageTagabstractoperationreturnsthecanonicalandcase-regularizedformofthelocaleargument(whichmustbeaStringvaluethatisastructurallyvalidBCP47languagetagasveriLiedbytheIsStructurallyValidLanguageTagabstractoperation).IttakesthestepsspeciLiedinRFC5646section4.5,orsuccessor,tobringthelanguagetagintocanonicalform,andtoregularizethecaseofthesubtags,butdoesnottakethestepstobringalanguagetaginto"extlangform"andtoreordervariantsubtags.

6.2.2 IsStructurallyValidLanguageTag(locale)

6.2.3 CanonicalizeLanguageTag(locale)

ThespeciLicationsforextensionstoBCP47languagetags,suchasRFC6067,mayincludecanonicalizationrulesfortheextensionsubtagsequencestheydeLinethatgobeyondthecanonicalizationrulesofRFC5646section4.5.Implementationsareallowed,butnotrequired,toapplytheseadditionalrules.

TheDefaultLocaleabstractoperationreturnsaStringvaluerepresentingthestructurallyvalid(6.2.2)andcanonicalized(6.2.3)BCP47languagetagforthehostenvironment’scurrentlocale.

TheECMAScript2017InternationalizationAPISpeciLicationidentiLiescurrenciesusing3-lettercurrencycodesasdeLinedbyISO4217.Theircanonicalformisuppercase.

Allwell-formed3-letterISO4217currencycodesareallowed.However,thesetofcombinationsofcurrencycodeandlanguagetagforwhichlocalizedcurrencysymbolsareavailableisimplementationdependent.Wherealocalizedcurrencysymbolisnotavailable,theISO4217currencycodeisusedforformatting.

TheIsWellFormedCurrencyCodeabstractoperationveriLiesthatthecurrencyargument(whichmustbeaStringvalue)representsawell-formed3-letterISOcurrencycode.Thefollowingstepsaretaken:

1. Letnormalizedbetheresultofmappingcurrencytouppercaseasdescribedin6.1.

6.2.4 DefaultLocale()

6.3 CurrencyCodes

6.3.1 IsWellFormedCurrencyCode(currency)

2. Ifthestringlengthofnormalizedisnot3,returnfalse.3. Ifnormalizedcontainsanycharacterthatisnotintherange"A"to"Z"(U+0041toU+005A),returnfalse.

4. Returntrue.

TheECMAScript2017InternationalizationAPISpeciLicationidentiLiestimezonesusingtheZoneandLinknamesoftheIANATimeZoneDatabase.TheircanonicalformisthecorrespondingZonenameinthecasingusedintheIANATimeZoneDatabase.

AllregisteredZoneandLinknamesareallowed.Implementationsmustrecognizeallsuchnames,andusebestavailablecurrentandhistoricalinformationabouttheiroffsetsfromUTCandtheirdaylightsavingtimerulesincalculations.However,thesetofcombinationsoftimezonenameandlanguagetagforwhichlocalizedtimezonenamesareavailableisimplementationdependent.

TheIsValidTimeZoneNameabstractoperationveriLiesthatthetimeZoneargument(whichmustbeaStringvalue)representsavalidZoneorLinknameoftheIANATimeZoneDatabase.

TheabstractoperationreturnstrueiftimeZone,convertedtouppercaseasdescribedin6.1,isequaltooneoftheZoneorLinknamesoftheIANATimeZoneDatabase,convertedtouppercaseasdescribedin6.1.Itreturnsfalseotherwise.

6.4 TimeZoneNames

6.4.1 IsValidTimeZoneName(timeZone)

6.4.2 CanonicalizeTimeZoneName

TheCanonicalizeTimeZoneNameabstractoperationreturnsthecanonicalandcase-regularizedformofthetimeZoneargument(whichmustbeaStringvaluethatisavalidtimezonenameasveriLiedbytheIsValidTimeZoneNameabstractoperation).Thefollowingstepsaretaken:

1. LetianaTimeZonebetheZoneorLinknameoftheIANATimeZoneDatabasesuchthattimeZone,convertedtouppercaseasdescribedin6.1,isequaltoianaTimeZone,convertedtouppercaseasdescribedin6.1.

2. IfianaTimeZoneisaLinkname,letianaTimeZonebethecorrespondingZonenameasspeciLiedinthe"backward"LileoftheIANATimeZoneDatabase.

3. IfianaTimeZoneis"Etc/UTC"or"Etc/GMT",return"UTC".4. ReturnianaTimeZone.

TheIntl.DateTimeFormatconstructorallowsthistimezonename;ifthetimezoneisnotspeciLied,thehostenvironment’scurrenttimezoneisused.ImplementationsshallsupportUTCandthehostenvironment’scurrenttimezone(ifdifferentfromUTC)informatting.

TheDefaultTimeZoneabstractoperationreturnsaStringvaluerepresentingthevalid(6.4.1)andcanonicalized(6.4.2)timezonenameforthehostenvironment’scurrenttimezone.

6.4.3 DefaultTimeZone()

7 RequirementsforStandardBuilt-inECMAScriptObjects

UnlessspeciLiedotherwiseinthisdocument,theobjects,functions,andconstructorsdescribedinthisstandardaresubjecttothegenericrequirementsandrestrictionsspeciLiedforstandardbuilt-inECMAScriptobjectsintheECMAScript2017LanguageSpeciLication,8thedition,clause17,orsuccessor.

TheIntlobjectisthe%Intl%intrinsicobjectandtheinitialvalueoftheIntlpropertyoftheglobalobject.TheIntlobjectisasingleordinaryobject.

Thevalueofthe[[Prototype]]internalslotoftheIntlobjectistheintrinsicobject%ObjectPrototype%.

TheIntlobjectisnotafunctionobject.Itdoesnothavea[[Construct]]internalmethod;itisnotpossibletousetheIntlobjectasaconstructorwiththenewoperator.TheIntlobjectdoesnothavea[[Call]]internalmethod;itisnotpossibletoinvoketheIntlobjectasafunction.

TheIntlobjecthasaninternalslot,[[FallbackSymbol]],whichisanew%Symbol%inthecurrentrealm.

See10.

8 TheIntlObject

8.1 ConstructorPropertiesoftheIntlObject

8.1.1 Intl.Collator(...)

https://tc39.github.io/ecma262/#global-object

https://tc39.github.io/ecma262/#sec-properties-of-the-object-prototype-object

https://tc39.github.io/ecma262/#sec-symbol-constructor

https://tc39.github.io/ecma262/#realm

See11.

See12.

WhenthegetCanonicalLocalesmethodiscalledwithargumentlocales,thefollowingstepsaretaken:

1. Letllbe?CanonicalizeLocaleList(locales).2. ReturnCreateArrayFromList(ll).

Theconstructorsfortheobjectsprovidinglocalesensitiveservices,Collator,NumberFormat,andDateTimeFormat,useacommonpatterntonegotiatetherequestsrepresentedbythelocalesandoptionsargumentsagainsttheactualcapabilitiesoftheirimplementations.Thecommonbehaviourisdescribedhereintermsofinternalslotsdescribingthecapabilitiesandofabstractoperationsusingtheseinternalslots.

8.1.2 Intl.NumberFormat(...)

8.1.3 Intl.DateTimeFormat(...)

8.2 FunctionPropertiesoftheIntlObject

8.2.1 Intl.getCanonicalLocales(locales)

9 LocaleandParameterNegotiation

https://tc39.github.io/ecma262/#sec-createarrayfromlist

TheconstructorsIntl.Collator,Intl.NumberFormat,andIntl.DateTimeFormathavethefollowinginternalslots:

[[AvailableLocales]]isaListthatcontainsstructurallyvalid(6.2.2)andcanonicalized(6.2.3)BCP47languagetagsidentifyingthelocalesforwhichtheimplementationprovidesthefunctionalityoftheconstructedobjects.LanguagetagsonthelistmustnothaveaUnicodelocaleextensionsequence.ThelistmustincludethevaluereturnedbytheDefaultLocaleabstractoperation(6.2.4),andmustnotincludeduplicates.Implementationsmustincludein[[AvailableLocales]]localesthatcanserveasfallbacksinthealgorithmusedtoresolvelocales(see9.2.6).Forexample,implementationsthatprovidea"de-DE"localemustincludea"de"localethatcanserveasafallbackforrequestssuchas"de-AT"and"de-CH".Forlocalesthatincurrentusagewouldincludeascriptsubtag(suchasChineselocales),old-stylelanguagetagswithoutscriptsubtagsmustbeincludedsuchthat,forexample,requestsfor"zh-TW"and"zh-HK"leadtooutputintraditionalChineseratherthanthedefaultsimpliLiedChinese.Theorderingofthelocaleswithin[[AvailableLocales]]isirrelevant.[[RelevantExtensionKeys]]isaListofkeysofthelanguagetagextensionsdeLinedinUnicodeTechnicalStandard35thatarerelevantforthefunctionalityoftheconstructedobjects.[[SortLocaleData]]and[[SearchLocaleData]](forIntl.Collator)and[[LocaleData]](forIntl.NumberFormatandIntl.DateTimeFormat)areobjectsthathavepropertiesforeachlocalecontainedin[[AvailableLocales]].Thevalueofeachofthesepropertiesmustbeanobjectthathaspropertiesforeachkeycontainedin[[RelevantExtensionKeys]].Thevalueofeachofthesepropertiesmustbeanon-emptyarrayofthosevaluesdeLinedinUnicodeTechnicalStandard35forthegivenkeythat

9.1 InternalslotsofServiceConstructors



aresupportedbytheimplementationforthegivenlocale,withtheLirstelementprovidingthedefaultvalue.

EXAMPLEAnimplementationofDateTimeFormatmightincludethelanguagetag"th"inits[[AvailableLocales]]internalslot,andmust(accordingto14.3)includethekey"ca"inits[[RelevantExtensionKeys]]internalslot.ForThai,the"buddhist"calendarisusuallythedefault,butanimplementationmightalsosupportthecalendars"gregory","chinese",and"islamicc"forthelocale"th".The[[LocaleData]]internalslotwouldthereforeatleastinclude{"th":{ca:["buddhist","gregory","chinese","islamicc"]}}.

WherethefollowingabstractoperationstakeanavailableLocalesargument,itmustbean[[AvailableLocales]]ListasspeciLiedin9.1.

TheabstractoperationCanonicalizeLocaleListtakesthefollowingsteps:

1. Iflocalesisunde9ined,thena. ReturnanewemptyList.

2. LetseenbeanewemptyList.3. IfType(locales)isString,then

a. LetObeCreateArrayFromList(«locales»).4. Else,

a. LetObe?ToObject(locales).5. Letlenbe?ToLength(?Get(O,"length")).6. Letkbe0.7. Repeat,whilek<len

a. LetPkbeToString(k).

9.2 AbstractOperations

9.2.1 CanonicalizeLocaleList(locales)




https://tc39.github.io/ecma262/#sec-ecmascript-data-types-and-values


https://tc39.github.io/ecma262/#sec-toobject

https://tc39.github.io/ecma262/#sec-tolength

https://tc39.github.io/ecma262/#sec-get-o-p

https://tc39.github.io/ecma262/#sec-tostring

b. LetkPresentbe?HasProperty(O,Pk).c. IfkPresentistrue,then

i. LetkValuebe?Get(O,Pk).ii. IfType(kValue)isnotStringorObject,throwaTypeErrorexception.

iii. Lettagbe?ToString(kValue).iv. IfIsStructurallyValidLanguageTag(tag)isfalse,

throwaRangeErrorexception.v. LetcanonicalizedTagbeCanonicalizeLanguageTag(tag).

vi. IfcanonicalizedTagisnotanelementofseen,appendcanonicalizedTagasthelastelementofseen.

d. Increasekby1.8. Returnseen.

NOTE1 Non-normativesummary:TheabstractoperationinterpretsthelocalesargumentasanarrayandcopiesitselementsintoaList,validatingtheelementsasstructurallyvalidlanguagetagsandcanonicalizingthem,andomittingduplicates.

NOTE2 RequiringkValuetobeaStringorObjectmeansthattheNumbervalueNaNwillnotbeinterpretedasthelanguagetag"nan",whichstandsforMinNanChinese.

TheBestAvailableLocaleabstractoperationcomparestheprovidedargumentlocale,whichmustbeaStringvaluewithastructurallyvalidandcanonicalizedBCP47languagetag,againstthelocalesinavailableLocalesandreturnseitherthelongestnon-emptypreLixoflocalethatisanelementofavailableLocales,orunde9inedifthereisnosuchelement.ItusesthefallbackmechanismofRFC4647,section

9.2.2 BestAvailableLocale(availableLocales,locale)


https://tc39.github.io/ecma262/#sec-hasproperty




3.4.Thefollowingstepsaretaken:

1. Letcandidatebelocale.2. Repeat

a. IfavailableLocalescontainsanelementequaltocandidate,returncandidate.

b. Letposbethecharacterindexofthelastoccurrenceof"-"(U+002D)withincandidate.Ifthatcharacterdoesnotoccur,returnunde9ined.

c. Ifpos≥2andthecharacter"-"occursatindexpos-2ofcandidate,decreaseposby2.

d. Letcandidatebethesubstringofcandidatefromposition0,inclusive,topositionpos,exclusive.

TheLookupMatcherabstractoperationcomparesrequestedLocales,whichmustbeaListasreturnedbyCanonicalizeLocaleList,againstthelocalesinavailableLocalesanddeterminesthebestavailablelanguagetomeettherequest.Thefollowingstepsaretaken:

1. Letkbe0.2. LetrLocalesbeCreateArrayFromList(requestedLocales).3. Letlenbe!ToLength(!Get(rLocales,"length")).4. LetavailableLocalebeunde9ined.5. Repeatwhilek<lenandavailableLocaleisunde9ined:

a. Letlocalebe!Get(rLocales,!ToString(k)).b. LetnoExtensionsLocalebetheStringvaluethatislocalewithallUnicodelocaleextensionsequencesremoved.

c. LetavailableLocalebeBestAvailableLocale(availableLocales,noExtensionsLocale).

d. Increasekby1.6. LetresultbeanewRecord.

9.2.3 LookupMatcher(availableLocales,requestedLocales)








7. IfavailableLocaleisnotunde9ined,thena. Setresult.[[locale]]toavailableLocale.b. IflocaleandnoExtensionsLocalearenotthesameStringvalue,theni. LetextensionbetheStringvalueconsistingoftheLirstsubstringoflocalethatisaUnicodelocaleextensionsequence.

ii. Setresult.[[extension]]toextension.8. Else,

a. LetdefLocalebeDefaultLocale().b. Setresult.[[locale]]todefLocale.

9. Returnresult.

NOTE ThealgorithmisbasedontheLookupalgorithmdescribedinRFC4647section3.4,butoptionsspeciLiedthroughUnicodelocaleextensionsequencesareignoredinthelookup.Informationaboutsuchsubsequencesisreturnedseparately.Theabstractoperationreturnsarecordwitha[[locale]]Lield,whosevalueisthelanguagetagoftheselectedlocale,whichmustbeanelementofavailableLocales.IfthelanguagetagoftherequestlocalethatledtotheselectedlocalecontainedaUnicodelocaleextensionsequence,thenthereturnedrecordalsocontainsan[[extension]]LieldwhosevalueistheLirstUnicodelocaleextensionsequencewithintherequestlocalelanguagetag.

TheBestFitMatcherabstractoperationcomparesrequestedLocales,whichmustbeaListasreturnedbyCanonicalizeLocaleList,againstthelocalesinavailableLocalesanddeterminesthebestavailable

9.2.4 BestFitMatcher(availableLocales,requestedLocales)


languagetomeettherequest.Thealgorithmisimplementationdependent,butshouldproduceresultsthatatypicaluseroftherequestedlocaleswouldperceiveasatleastasgoodasthoseproducedbytheLookupMatcherabstractoperation.OptionsspeciLiedthroughUnicodelocaleextensionsequencesmustbeignoredbythealgorithm.Informationaboutsuchsubsequencesisreturnedseparately.Theabstractoperationreturnsarecordwitha[[locale]]Lield,whosevalueisthelanguagetagoftheselectedlocale,whichmustbeanelementofavailableLocales.IfthelanguagetagoftherequestlocalethatledtotheselectedlocalecontainedaUnicodelocaleextensionsequence,thenthereturnedrecordalsocontainsan[[extension]]LieldwhosevalueistheLirstUnicodelocaleextensionsequencewithintherequestlocalelanguagetag.

TheabstractoperationUnicodeExtensionSubtagssplitsextension,whichmustbeaUnicodelocaleextensionsequence,intoitssubtags.Thefollowingstepsaretaken:

1. Letsizebethenumberofelementsinextension.2. Ifsize=0,then

a. Return«».3. LetextensionSubtagsbe«».4. Letattributebetrue.5. Letqbe3.6. Letpbeq.7. Lettbeq.8. Repeat,whileq<size

a. LetcbethecodeunitvalueoftheelementatindexqintheStringextension.

b. Ifcis0x002D(HYPHEN-MINUS),theni. Ifq-p=2,then

9.2.5 UnicodeExtensionSubtags(extension)

1. Ifp-t>1,thena. LettypebeaStringvalueequaltothesubstringofextensionconsistingofthecodeunitsatindicest(inclusive)throughp-1(exclusive).

b. AppendtypeasthelastelementofextensionSubtags.

2. LetkeybeaStringvalueequaltothesubstringofextensionconsistingofthecodeunitsatindicesp(inclusive)throughq(exclusive).

3. AppendkeyasthelastelementofextensionSubtags.

4. Lettbeq+1.5. Letattributebefalse.

ii. Elseifattributeistrue,then1. LetattrbeaStringvalueequaltothesubstringofextensionconsistingofthecodeunitsatindicesp(inclusive)throughq(exclusive).

2. AppendattrasthelastelementofextensionSubtags.

3. Lettbeq+1.iii. Letpbeq+1.

c. Letqbeq+1.9. Ifsize-p=2,then

a. Ifp-t>1,theni. LettypebeaStringvalueequaltothesubstringofextensionconsistingofthecodeunitsatindicest(inclusive)throughp-1(exclusive).

ii. AppendtypeasthelastelementofextensionSubtags.b. Lettbep.

10. LettailbeaStringvalueequaltothesubstringofextensionconsistingofthecodeunitsatindicest(inclusive)throughsize(exclusive).

11. AppendtailasthelastelementofextensionSubtags.12. ReturnextensionSubtags.

TheResolveLocaleabstractoperationcomparesaBCP47languageprioritylistrequestedLocalesagainstthelocalesinavailableLocalesanddeterminesthebestavailablelanguagetomeettherequest.availableLocales,requestedLocales,andrelevantExtensionKeysmustbeprovidedasListvalues,optionsasaRecord.

Thefollowingstepsaretaken:

1. Letmatcherbeoptions.[[localeMatcher]].2. Ifmatcheris"lookup",then

a. LetrbeLookupMatcher(availableLocales,requestedLocales).

3. Else,a. LetrbeBestFitMatcher(availableLocales,requestedLocales).

4. LetfoundLocaleber.[[locale]].5. Ifrhasan[[extension]]Lield,then

a. Letextensionber.[[extension]].b. LetextensionSubtagsbeCreateArrayFromList(UnicodeExtensionSubtags(extension)).

c. LetextensionSubtagsLengthbeGet(extensionSubtags,"length").

6. LetresultbeanewRecord.7. Setresult.[[dataLocale]]tofoundLocale.8. LetsupportedExtensionbe"-u".9. Letkbe0.10. LetrExtensionKeysbe

9.2.6 ResolveLocale(availableLocales,requestedLocales,options,relevantExtensionKeys,localeData)






CreateArrayFromList(relevantExtensionKeys).11. Letlenbe!ToLength(!Get(rExtensionKeys,"length")).12. Repeatwhilek<len

a. Letkeybe!Get(rExtensionKeys,!ToString(k)).b. LetfoundLocaleDatabe?Get(localeData,foundLocale).c. LetkeyLocaleDatabe?ToObject(Get(foundLocaleData,key)).

d. Letvaluebe?ToString(Get(keyLocaleData,"0")).e. LetsupportedExtensionAdditionbe"".f. IfextensionSubtagsisnotunde9ined,then

i. LetkeyPosbeCall(%ArrayProto_indexOf%,extensionSubtags,«key»).

ii. IfkeyPos≠-1,then1. IfkeyPos+1<extensionSubtagsLengthandthe

lengthpropertyoftheresultofGet(extensionSubtags,ToString(keyPos+1))isgreaterthan2,thena. LetrequestedValuebeGet(extensionSubtags,ToString(keyPos+1)).

b. IftheresultofCall(%StringProto_includes%,keyLocaleData,«requestedValue»)istrue,theni. LetvalueberequestedValue.ii. LetsupportedExtensionAdditionbetheconcatenationof"-",key,"-",andvalue.

2. ElseiftheresultofCall(%StringProto_includes%,keyLocaleData,«"true"»)istrue,thena. Letvaluebe"true".

g. IfoptionshasaLield[[<key>]],then











https://tc39.github.io/ecma262/#sec-call







i. LetoptionsValuebe?ToString(options.[[<key>]]).ii. IftheresultofCall(%StringProto_includes%,keyLocaleData,«optionsValue»)istrue,then1. IfoptionsValueisnotequaltovalue,then

a. LetvaluebeoptionsValue.b. LetsupportedExtensionAdditionbe"".

h. Setresult.[[<key>]]tovalue.i. AppendsupportedExtensionAdditiontosupportedExtension.

j. Increasekby1.13. IfthenumberofelementsinsupportedExtensionisgreaterthan

2,thena. LetprivateIndexbeCall(%StringProto_indexOf%,foundLocale,«"-x-"»).

b. IfprivateIndex=-1,theni. LetfoundLocalebetheconcatenationoffoundLocaleandsupportedExtension.

c. Else,i. LetpreExtensionbethesubstringoffoundLocalefromposition0,inclusive,topositionprivateIndex,exclusive.

ii. LetpostExtensionbethesubstringoffoundLocalefrompositionprivateIndextotheendofthestring.

iii. LetfoundLocalebetheconcatenationofpreExtension,supportedExtension,andpostExtension.

d. Assert:IsStructurallyValidLanguageTag(foundLocale)istrue.

e. LetfoundLocalebeCanonicalizeLanguageTag(foundLocale).

14. Setresult.[[locale]]tofoundLocale.15. Returnresult.

NOTE Non-normativesummary:Twoalgorithmsareavailabletomatchthelocales:theLookupalgorithm




describedinRFC4647section3.4,andanimplementationdependentbest-Litalgorithm.Independentofthelocalematchingalgorithm,optionsspeciLiedthroughUnicodelocaleextensionsequencesarenegotiatedseparately,takingthecaller’srelevantextensionkeysandlocaledataaswellasclient-providedoptionsintoconsideration.Theabstractoperationreturnsarecordwitha[[locale]]Lieldwhosevalueisthelanguagetagoftheselectedlocale,andLieldsforeachkeyinrelevantExtensionKeysprovidingtheselectedvalueforthatkey.

TheLookupSupportedLocalesabstractoperationreturnsthesubsetoftheprovidedBCP47languageprioritylistrequestedLocalesforwhichavailableLocaleshasamatchinglocalewhenusingtheBCP47Lookupalgorithm.LocalesappearinthesameorderinthereturnedlistasinrequestedLocales.Thefollowingstepsaretaken:

1. LetrLocalesbeCreateArrayFromList(requestedLocales).2. Letlenbe!ToLength(!Get(rLocales,"length")).3. LetsubsetbeanewemptyList.4. Letkbe0.5. Repeatwhilek<len

a. Letlocalebe!Get(rLocales,!ToString(k)).b. LetnoExtensionsLocalebetheStringvaluethatislocalewithallUnicodelocaleextensionsequencesremoved.

c. LetavailableLocalebeBestAvailableLocale(availableLocales,noExtensionsLocale).

d. IfavailableLocaleisnotunde9ined,appendlocaletotheendofsubset.

e. Incrementkby1.

9.2.7 LookupSupportedLocales(availableLocales,requestedLocales)







6. Returnsubset.

TheBestFitSupportedLocalesabstractoperationreturnsthesubsetoftheprovidedBCP47languageprioritylistrequestedLocalesforwhichavailableLocaleshasamatchinglocalewhenusingtheBestFitMatcheralgorithm.LocalesappearinthesameorderinthereturnedlistasinrequestedLocales.Thestepstakenareimplementationdependent.

TheSupportedLocalesabstractoperationreturnsthesubsetoftheprovidedBCP47languageprioritylistrequestedLocalesforwhichavailableLocaleshasamatchinglocale.Twoalgorithmsareavailabletomatchthelocales:theLookupalgorithmdescribedinRFC4647section3.4,andanimplementationdependentbest-Litalgorithm.LocalesappearinthesameorderinthereturnedlistasinrequestedLocales.Thefollowingstepsaretaken:

1. Ifoptionsisnotunde9ined,thena. Letmatcherbe?GetOption(options,"localeMatcher","string",«"lookup","best9it"»,"best9it").

2. Else,letmatcherbe"best9it".3. Ifmatcheris"best9it",

a. LetsupportedLocalesbeBestFitSupportedLocales(availableLocales,requestedLocales).

4. Else,a. LetsupportedLocalesbeLookupSupportedLocales(availableLocales,

9.2.8 BestFitSupportedLocales(availableLocales,requestedLocales)

9.2.9 SupportedLocales(availableLocales,requestedLocales,options)

requestedLocales).5. LetsubsetbeCreateArrayFromList(supportedLocales).6. Letkeysbesubset.[[OwnPropertyKeys]]().7. RepeatforeachelementPofkeysinListorder,

a. LetdescbePropertyDescriptor{[[ConLigurable]]:false,[[Writable]]:false}.

b. Perform!DeLinePropertyOrThrow(subset,P,desc).8. Returnsubset.

TheabstractoperationGetOptionextractsthevalueofthepropertynamedpropertyfromtheprovidedoptionsobject,convertsittotherequiredtype,checkswhetheritisoneofaListofallowedvalues,andLillsinafallbackvalueifnecessary.

1. Letoptsbe?ToObject(options).2. Letvaluebe?Get(opts,property).3. Ifvalueisnotunde9ined,then

a. Assert:typeis"boolean"or"string".b. Iftypeis"boolean",then

i. LetvaluebeToBoolean(value).c. Iftypeis"string",then

i. Letvaluebe?ToString(value).d. Ifvaluesisnotunde9ined,then

i. Ifvaluesdoesnotcontainanelementequaltovalue,throwaRangeErrorexception.

e. Returnvalue.4. Else,returnfallback.

9.2.10 GetOption(options,property,type,values,fallback)

9.2.11 GetNumberOption(options,property,minimum,maximum,fallback)



https://tc39.github.io/ecma262/#sec-definepropertyorthrow




https://tc39.github.io/ecma262/#sec-toboolean


TheabstractoperationGetNumberOptionextractsthevalueofthepropertynamedpropertyfromtheprovidedoptionsobject,convertsittoaNumbervalue,checkswhetheritisintheallowedrange,andLillsinafallbackvalueifnecessary.

1. Letoptsbe?ToObject(options).2. Letvaluebe?Get(opts,property).3. Ifvalueisnotunde9ined,then

a. Letvaluebe?ToNumber(value).b. IfvalueisNaNorlessthanminimumorgreaterthanmaximum,throwaRangeErrorexception.

c. ReturnLloor(value).4. Else,returnfallback.

TheIntl.Collatorconstructoristhe%Collator%intrinsicobjectandastandardbuilt-inpropertyoftheIntlobject.BehaviourcommontoallserviceconstructorpropertiesoftheIntlobjectisspeciLiedin9.1.

TheabstractoperationInitializeCollatoracceptstheargumentscollator(whichmustbeanobject),locales,andoptions.ItinitializescollatorasaCollatorobject.

Severalstepsinthealgorithmusevaluesfromthefollowingtable,whichassociatesUnicodelocaleextensionkeys,internalslots,

10 CollatorObjects

10.1 TheIntl.CollatorConstructor

10.1.1 InitializeCollator(collator,locales,options)



https://tc39.github.io/ecma262/#sec-tonumber

https://tc39.github.io/ecma262/#sec-algorithm-conventions

propertynames,types,andallowablevalues:

Table2:Collatoroptionssettablethroughextensionkeys,internalslotsandoptionsproperties

Key InternalSlot

Property Type Values

kn [[Numeric]] "numeric" "boolean"

kf [[CaseFirst]] "caseFirst" "string" "upper","lower","false"


1. Ifcollator.[[InitializedIntlObject]]istrue,throwaTypeErrorexception.

2. Setcollator.[[InitializedIntlObject]]totrue.3. LetrequestedLocalesbe?CanonicalizeLocaleList(locales).4. Ifoptionsisunde9ined,then

a. LetoptionsbeObjectCreate(%ObjectPrototype%).5. Else,

a. Letoptionsbe?ToObject(options).6. Letube?GetOption(options,"usage","string",«"sort","search"»,"sort").

7. Setcollator.[[Usage]]tou.8. Ifuis"sort",then

a. LetlocaleDatabe%Collator%.[[SortLocaleData]].9. Else,

a. LetlocaleDatabe%Collator%.[[SearchLocaleData]].10. LetoptbeanewRecord.11. Letmatcherbe?GetOption(options,"localeMatcher","string",

«"lookup","best9it"»,"best9it").12. Setopt.[[localeMatcher]]tomatcher.

https://tc39.github.io/ecma262/#sec-objectcreate




13. ForeachrowinTable2,excepttheheaderrow,do:a. LetkeybethenamegivenintheKeycolumnoftherow.b. LetpropbethenamegiveninthePropertycolumnoftherow.

c. LettypebethestringgivenintheTypecolumnoftherow.d. LetlistbeaListcontainingtheStringsgivenintheValuescolumnoftherow,orunde9inedifnostringsaregiven.

e. Letvaluebe?GetOption(options,prop,type,list,unde9ined).

f. IfthestringgivenintheTypecolumnoftherowis"boolean"andvalueisnotunde9ined,theni. Letvaluebe!ToString(value).

g. Setopt.[[<key>]]tovalue.14. LetrelevantExtensionKeysbe%Collator%.

[[RelevantExtensionKeys]].15. LetrbeResolveLocale(%Collator%.[[AvailableLocales]],

requestedLocales,opt,relevantExtensionKeys,localeData).16. Setcollator.[[Locale]]tor.[[locale]].17. Letkbe0.18. LetrExtensionKeysbe

CreateArrayFromList(relevantExtensionKeys).19. Letlenbe!ToLength(!Get(rExtensionKeys,"length")).20. Repeatwhilek<len:

a. Letkeybe!Get(rExtensionKeys,!ToString(k)).b. Ifkeyis"co",then

i. Letvalueber.[[co]].ii. Ifvalueisnull,letvaluebe"default".iii. Setcollator.[[Collation]]tovalue.

c. ElseusetherowofTable2thatcontainskeyintheKeycolumn:i. Letvalueber.[[<key>]].ii. IfthenamegivenintheTypecolumnoftherowis"boolean",letvaluebetheresultofcomparingvalue








with"true".iii. Setcollator'sinternalslotwhosenameistheInternal

Slotcolumnoftherowtovalue.d. Increasekby1.

21. Letsbe?GetOption(options,"sensitivity","string",«"base","accent","case","variant"»,unde9ined).

22. Ifsisunde9ined,thena. Ifuis"sort",then

i. Letsbe"variant".b. Else,

i. LetdataLocaleber.[[dataLocale]].ii. LetdataLocaleDatabeGet(localeData,dataLocale).iii. LetsbeGet(dataLocaleData,"sensitivity").

23. Setcollator.[[Sensitivity]]tos.24. Letipbe?GetOption(options,"ignorePunctuation",

"boolean",unde9ined,false).25. Setcollator.[[IgnorePunctuation]]toip.26. Setcollator.[[BoundCompare]]tounde9ined.27. Setcollator.[[InitializedCollator]]totrue.28. Returncollator.

WhentheIntl.Collatorfunctioniscalledwithoptionalargumentslocalesandoptions,thefollowingstepsaretaken:

1. IfNewTargetisunde9ined,letnewTargetbetheactivefunctionobject,elseletnewTargetbeNewTarget.

2. LetinternalSlotsListbe«[[InitializedIntlObject]],[[InitializedCollator]],[[Locale]],[[Usage]],[[Sensitivity]],[[IgnorePunctuation]],[[Collation]],[[BoundCompare]]».

3. If%Collator%.[[RelevantExtensionKeys]]contains"kn",thena. Append[[Numeric]]asthelastelementof

10.1.2 Intl.Collator([locales[,options]])



https://tc39.github.io/ecma262/#active-function-object

internalSlotsList.4. If%Collator%.[[RelevantExtensionKeys]]contains"kf",then

a. Append[[CaseFirst]]asthelastelementofinternalSlotsList.

5. Letcollatorbe?OrdinaryCreateFromConstructor(newTarget,"%CollatorPrototype%",internalSlotsList).

6. Return?InitializeCollator(collator,locales,options).

TheIntl.Collatorconstructorhasthefollowingproperties:

ThevalueofIntl.Collator.prototypeis%CollatorPrototype%.

Thispropertyhastheattributes{[[Writable]]:false,[[Enumerable]]:false,[[ConLigurable]]:false}.

WhenthesupportedLocalesOfmethodiscalled,thefollowingstepsaretaken:

1. LetrequestedLocalesbe?CanonicalizeLocaleList(locales).2. Return?SupportedLocales(%Collator%.[[AvailableLocales]],requestedLocales,options).

ThevalueofthelengthpropertyofthesupportedLocalesOfmethodis1.

10.2 PropertiesoftheIntl.CollatorConstructor

10.2.1 Intl.Collator.prototype

10.2.2 Intl.Collator.supportedLocalesOf(locales[,options])

https://tc39.github.io/ecma262/#sec-ordinarycreatefromconstructor

Thevalueofthe[[AvailableLocales]]internalslotisimplementationdeLinedwithintheconstraintsdescribedin9.1.Thevalueofthe[[RelevantExtensionKeys]]internalslotisaListthatmustincludetheelement"co",mayincludeanyoralloftheelements"kn"and"kf",andmustnotincludeanyotherelements.

NOTE UnicodeTechnicalStandard35describestenlocaleextensionkeysthatarerelevanttocollation:"co"forcollatorusageandspecializations,"ka"foralternatehandling,"kb"forbackwardsecondlevelweight,"kc"forcaselevel,"kn"fornumeric,"kh"forhiraganaquaternary,"kk"fornormalization,"kf"forcaseLirst,"kr"forreordering,"ks"forcollationstrength,and"vt"forvariabletop.Collator,however,requiresthattheusageisspeciLiedthroughtheusagepropertyoftheoptionsobject,alternatehandlingthroughtheignorePunctuationpropertyoftheoptionsobject,andcaselevelandthestrengththroughthesensitivitypropertyoftheoptionsobject.The"co"keyinthelanguagetagissupportedonlyforcollatorspecializations,andthekeys"kb","kh","kk","kr",and"vt"arenotallowedinthisversionoftheInternationalizationAPI.Supportfortheremainingkeysisimplementationdependent.

Thevaluesofthe[[SortLocaleData]]and[[SearchLocaleData]]internalslotsareimplementationdeLinedwithintheconstraintsdescribedin9.1andthefollowingadditionalconstraints:

TheLirstelementof[[SortLocaleData]][locale].coand[[SearchLocaleData]][locale].comustbenullforalllocalevalues.Thevalues"standard"and"search"mustnotbeusedas

10.2.3 InternalSlots


elementsinany[[SortLocaleData]][locale].coand[[SearchLocaleData]][locale].coarray.[[SearchLocaleData]][locale]musthaveasensitivitypropertywithaStringvalueequalto"base","accent","case",or"variant"foralllocalevalues.

TheIntl.Collatorprototypeobjectistheintrinsicobject%CollatorPrototype%.TheIntl.CollatorprototypeobjectisitselfanIntl.CollatorinstanceasspeciLiedin10.4,whoseinternalslotsaresetasifithadbeenconstructedbytheexpressionConstruct(%Collator%,«»,%Object%).

Inthefollowingdescriptionsoffunctionsthatarepropertiesor[[Get]]attributesofpropertiesof%CollatorPrototype%,thephrase"thisCollatorobject"referstotheobjectthatisthethisvaluefortheinvocationofthefunction;aTypeErrorexceptionisthrownifthethisvalueisnotanobjectoranobjectthatdoesnothavean[[InitializedCollator]]internalslotwithvaluetrue.

TheinitialvalueofIntl.Collator.prototype.constructoristheintrinsicobject%Collator%.

Theinitialvalueofthe@@toStringTagpropertyisthestringvalue"Object".

10.3 PropertiesoftheIntl.CollatorPrototypeObject

10.3.1 Intl.Collator.prototype.constructor

10.3.2 Intl.Collator.prototype[@@toStringTag]

https://tc39.github.io/ecma262/#sec-construct

https://tc39.github.io/ecma262/#sec-object-constructor

Thispropertyhastheattributes{[[Writable]]:false,[[Enumerable]]:false,[[ConLigurable]]:true}.

ThisnamedaccessorpropertyreturnsafunctionthatcomparestwostringsaccordingtothesortorderofthisCollatorobject.

Thevalueofthe[[Get]]attributeisafunctionthattakesthefollowingsteps:

1. Letcollatorbethisvalue.2. IfType(collator)isnotObject,throwaTypeErrorexception.3. Ifcollatordoesnothavean[[InitializedCollator]]internalslot,throwaTypeErrorexception.

4. Ifcollator.[[BoundCompare]]isunde9ined,thena. LetFbeanewbuilt-infunctionobjectasdeLinedin10.3.4.b. LetbcbeBoundFunctionCreate(F,collator,«»).c. Perform!DeLinePropertyOrThrow(bc,"length",PropertyDescriptor{[[Value]]:2,[[Writable]]:false,[[Enumerable]]:false,[[ConLigurable]]:true}).

d. Setcollator.[[BoundCompare]]tobc.5. Returncollator.[[BoundCompare]].

NOTE Thefunctionreturnedby[[Get]]isboundtothisCollatorobjectsothatitcanbepasseddirectlytoArray.prototype.sortorotherfunctions.

Thevalueofthe[[Set]]attributeisunde9ined.

ACollatorcomparefunctionisananonymousbuilt-infunction.

10.3.3 getIntl.Collator.prototype.compare

10.3.4 CollatorCompareFunctions


https://tc39.github.io/ecma262/#sec-boundfunctioncreate


WhenaCollatorcomparefunctioniscalledwithargumentsxandy,thefollowingstepsaretaken:

1. Letcollatorbethethisvalue.2. Assert:Type(collator)isObjectandcollator.[[InitializedCollator]]istrue.

3. Ifxisnotprovided,letxbeunde9ined.4. Ifyisnotprovided,letybeunde9ined.5. LetXbe?ToString(x).6. LetYbe?ToString(y).7. ReturnCompareStrings(collator,X,Y).

WhentheCompareStringsabstractoperationiscalledwithargumentscollator(whichmustbeanobjectinitializedasaCollator),xandy(whichmustbeStringvalues),itreturnsaNumberotherthanNaNthatrepresentstheresultofalocale-sensitiveStringcomparisonofxwithy.ThetwoStringsarecomparedinanimplementation-deLinedfashion.TheresultisintendedtoorderStringvaluesinthesortorderspeciLiedbytheeffectivelocaleandcollationoptionscomputedduringconstructionofcollator,andwillbenegative,zero,orpositive,dependingonwhetherxcomesbeforeyinthesortorder,theStringsareequalunderthesortorder,orxcomesafteryinthesortorder,respectively.StringvaluesmustbeinterpretedasUTF-16codeunitsequences,andasurrogatepair(acodeunitintherange0xD800to0xDBFFfollowedbyacodeunitintherange0xDC00to0xDFFF)withinastringmustbeinterpretedasthecorrespondingcodepoint.

Thesensitivityofcollatorisinterpretedasfollows:

base:Onlystringsthatdifferinbaseletterscompareasunequal.Examples:a≠b,a=á,a=A.accent:Onlystringsthatdifferinbaselettersoraccentsandotherdiacriticmarkscompareasunequal.Examples:a≠b,a≠á,a=A.




case:Onlystringsthatdifferinbaselettersorcasecompareasunequal.Examples:a≠b,a=á,a≠A.variant:Stringsthatdifferinbaseletters,accentsandotherdiacriticmarks,orcasecompareasunequal.Otherdifferencesmayalsobetakenintoconsideration.Examples:a≠b,a≠á,a≠A.

NOTE1 Insomelanguages,certainletterswithdiacriticmarksareconsideredbaseletters.Forexample,inSwedish,“ö”isabaseletterthat’sdifferentfrom“o”.

Ifthecollatorissettoignorepunctuation,thenstringsthatdifferonlyinpunctuationcompareasequal.

Fortheinterpretationofoptionssettablethroughextensionkeys,seeUnicodeTechnicalStandard35.

TheCompareStringsabstractoperationwithanygivencollatorargument,ifconsideredasafunctionoftheremainingtwoargumentsxandy,mustbeaconsistentcomparisonfunction(asdeLinedinES2017,22.1.3.25)onthesetofallStrings.

Theactualreturnvaluesareimplementation-deLinedtopermitimplementerstoencodeadditionalinformationinthevalue.Themethodisrequiredtoreturn0whencomparingStringsthatareconsideredcanonicallyequivalentbytheUnicodestandard.

NOTE2 ItisrecommendedthattheCompareStringsabstractoperationbeimplementedfollowingUnicodeTechnicalStandard10,UnicodeCollationAlgorithm(availableathttp://unicode.org/reports/tr10/),usingtailoringsfortheeffectivelocaleandcollationoptionsofcollator.ItisrecommendedthatimplementationsusethetailoringsprovidedbytheCommonLocaleDataRepository(availableat

http://unicode.org/reports/tr10/

https://tc39.github.io/ecma262/#sec-array.prototype.sort

http://cldr.unicode.org/).

NOTE3 ApplicationsshouldnotassumethatthebehaviouroftheCompareStringsabstractoperationforCollatorinstanceswiththesameresolvedoptionswillremainthesamefordifferentversionsofthesameimplementation.

Thisfunctionprovidesaccesstothelocaleandcollationoptionscomputedduringinitializationoftheobject.

ThefunctionreturnsanewobjectwhosepropertiesandattributesaresetasifconstructedbyanobjectliteralassigningtoeachofthefollowingpropertiesthevalueofthecorrespondinginternalslotofthisCollatorobject(see10.4):locale,usage,sensitivity,ignorePunctuation,collation,aswellasthosepropertiesshowninTable2whosekeysareincludedinthe%Collator%.[[RelevantExtensionKeys]]internalslotofthestandardbuilt-inobjectthatistheinitialvalueofIntl.Collator.

Intl.Collatorinstancesareordinaryobjectsthatinheritpropertiesfrom%CollatorPrototype%.

Intl.CollatorinstancesandotherobjectsthathavebeensuccessfullyinitializedasaCollatorhave[[InitializedIntlObject]]and[[InitializedCollator]]internalslotswhosevaluesaretrue.

ObjectsthathavebeensuccessfullyinitializedasaCollatoralsohaveseveralinternalslotsthatarecomputedbytheconstructor:

10.3.5 Intl.Collator.prototype.resolvedOptions()

10.4 PropertiesofIntl.CollatorInstances

http://cldr.unicode.org/

[[Locale]]isaStringvaluewiththelanguagetagofthelocalewhoselocalizationisusedforcollation.[[Usage]]isoneoftheStringvalues"sort"or"search",identifyingthecollatorusage.[[Sensitivity]]isoneoftheStringvalues"base","accent","case",or"variant",identifyingthecollator’ssensitivity.[[IgnorePunctuation]]isaBooleanvalue,specifyingwhetherpunctuationshouldbeignoredincomparisons.[[Collation]]isaStringvaluewiththe"type"giveninUnicodeTechnicalStandard35forthecollation,exceptthatthevalues"standard"and"search"arenotallowed,whilethevalue"default"isallowed.

ObjectsthathavebeensuccessfullyinitializedasaCollatoralsohavethefollowinginternalslotsifthekeycorrespondingtothenameoftheinternalslotinTable2isincludedinthe[[RelevantExtensionKeys]]internalslotofIntl.Collator:

[[Numeric]]isaBooleanvalue,specifyingwhethernumericsortingisused.[[CaseFirst]]isaStringvalue;allowedvaluesarespeciLiedinTable2.

Finally,objectsthathavebeensuccessfullyinitializedasaCollatorhavea[[BoundCompare]]internalslotthatcachesthefunctionreturnedbythecompareaccessor(10.3.3).

11 NumberFormatObjects

11.1 AbstractOperationsForNumberFormatObjects

TheabstractoperationSetNumberFormatDigitOptionsappliesdigitoptionsusedfornumberformattingontotheintlobject.

1. Assert:Type(intlObj)isObjectandintlObj.[[InitializedIntlObject]]istrue.

2. Assert:Type(options)isObject.3. Assert:type(mnfdDefault)isNumber.4. Letmnidbe?GetNumberOption(options,"minimumIntegerDigits,",1,21,1).

5. Letmnfdbe?GetNumberOption(options,"minimumFractionDigits",0,20,mnfdDefault).

6. Letmxfdbe?GetNumberOption(options,"maximumFractionDigits",mnfd,20).

7. Letmnsdbe?Get(options,"minimumSigni9icantDigits").8. Letmxsdbe?Get(options,"maximumSigni9icantDigits").9. SetintlObj.[[MinimumIntegerDigits]]tomnid.10. SetintlObj.[[MinimumFractionDigits]]tomnfd.11. SetintlObj.[[MaximumFractionDigits]]tomxfd.12. Ifmnsdisnotunde9inedormxsdisnotunde9ined,then

a. Letmnsdbe?GetNumberOption(options,"minimumSigni9icantDigits",1,21,1).

b. Letmxsdbe?GetNumberOption(options,"maximumSigni9icantDigits",mnsd,21,21).

c. SetintlObj.[[MinimumSigniLicantDigits]]tomnsd.d. SetintlObj.[[MaximumSigniLicantDigits]]tomxsd.

TheabstractoperationInitializeNumberFormatacceptstheargumentsnumberFormat(whichmustbeanobject),locales,and

11.1.1 SetNumberFormatDigitOptions(intlObj,options,mnfdDefault)

11.1.2 InitializeNumberFormat(numberFormat,locales,options)





options.ItinitializesnumberFormatasaNumberFormatobject.


1. IfnumberFormat.[[InitializedIntlObject]]istrue,throwaTypeErrorexception.

2. SetnumberFormat.[[InitializedIntlObject]]totrue.3. LetrequestedLocalesbe?CanonicalizeLocaleList(locales).4. Ifoptionsisunde9ined,then

a. LetoptionsbeObjectCreate(%ObjectPrototype%).5. Else,

a. Letoptionsbe?ToObject(options).6. LetoptbeanewRecord.7. Letmatcherbe?GetOption(options,"localeMatcher","string",«"lookup","best9it"»,"best9it").

8. Setopt.[[localeMatcher]]tomatcher.9. LetlocaleDatabe%NumberFormat%.[[LocaleData]].10. LetrbeResolveLocale(%NumberFormat%.[[AvailableLocales]],

requestedLocales,opt,%NumberFormat%.[[RelevantExtensionKeys]],localeData).

11. SetnumberFormat.[[Locale]]tor.[[locale]].12. SetnumberFormat.[[NumberingSystem]]tor.[[nu]].13. LetdataLocaleber.[[dataLocale]].14. Letstylebe?GetOption(options,"style","string",«"decimal",

"percent","currency"»,"decimal").15. SetnumberFormat.[[Style]]tostyle.16. Letcbe?GetOption(options,"currency","string",unde9ined,

unde9ined).17. Ifcisnotunde9ined,then

a. IftheresultofIsWellFormedCurrencyCode(c)isfalse,throwaRangeErrorexception.

18. Ifstyleis"currency"andcisunde9ined,throwaTypeErrorexception.

19. Ifstyleis"currency",then





a. LetcbetheresultofconvertingctouppercaseasspeciLiedin6.1.

b. SetnumberFormat.[[Currency]]toc.c. LetcDigitsbeCurrencyDigits(c).

20. Letcdbe?GetOption(options,"currencyDisplay","string",«"code","symbol","name"»,"symbol").

21. Ifstyleis"currency",setnumberFormat.[[CurrencyDisplay]]tocd.

22. Ifstyleis"currency",thena. LetmnfdDefaultbecDigits.

23. Else,a. LetmnfdDefaultbe0.

24. Perform?SetNumberFormatDigitOptions(numberFormat,options,mnfdDefault).

25. IfnumberFormat.[[MaximumFractionDigits]]isunde9ined,thena. Ifstyleis"currency",then

i. SetnumberFormat.[[MaximumFractionDigits]]tomax(numberFormat.[[MinimumFractionDigits]],cDigits).

b. Elseifstyleis"percent",theni. SetnumberFormat.[[MaximumFractionDigits]]tomax(numberFormat.[[MinimumFractionDigits]],0).

c. Else,i. SetnumberFormat.[[MaximumFractionDigits]]tomax(numberFromat.[[MinimumFractionDigits]],3).

26. Letgbe?GetOption(options,"useGrouping","boolean",unde9ined,true).

27. SetnumberFormat.[[UseGrouping]]tog.28. LetdataLocaleDatabeGet(localeData,dataLocale).29. LetpatternsbeGet(dataLocaleData,"patterns").30. Assert:patternsisanobject(see11.3.3).31. LetstylePatternsbeGet(patterns,s).







32. SetnumberFormat.[[PositivePattern]]toGet(stylePatterns,"positivePattern").

33. SetnumberFormat.[[NegativePattern]]toGet(stylePatterns,"negativePattern").

34. SetnumberFormat.[[BoundFormat]]tounde9ined.35. SetnumberFormat.[[InitializedNumberFormat]]totrue.36. ReturnnumberFormat.

WhentheabstractoperationCurrencyDigitsiscalledwithanargumentcurrency(whichmustbeanuppercaseStringvalue),thefollowingstepsaretaken:

1. IftheISO4217currencyandfundscodelistcontainscurrencyasanalphabeticcode,returntheminorunitvaluecorrespondingtothecurrencyfromthelist;otherwise,return2.

ANumberformatfunctionisananonymousbuilt-infunction.

WhenaNumberformatfunctioniscalledwithoptionalargumentvalue,thefollowingstepsaretaken:

1. Letnfbethethisvalue.2. Assert:Type(nf)isObjectandnf.[[InitializedNumberFormat]]istrue.

3. Ifvalueisnotprovided,letvaluebeunde9ined.4. Letxbe?ToNumber(value).5. ReturnFormatNumber(nf,x).

ThelengthpropertyofaNumberformatfunctionis1.

11.1.3 CurrencyDigits(currency)

11.1.4 NumberFormatFunctions





TheFormatNumberToStringabstractoperationiscalledwithargumentsnumberFormat(whichmustbeanobjectwithLieldsminimumSigniLicantDigits,maximumSigniLicantDigits,minimumIntegerDigits,minimumFractionDigitsandmaximumFractionDigits),andx(whichmustbeaNumbervalue),andreturnsxasastringvaluewithdigitsformattedaccordingtothe5formattingparameters.

1. Assert:numberFormat.[[InitializedIntlObject]]istrue.2. IfthenumberFormat.[[MinimumSigniLicantDigits]]andnumberFormat.[[MaximumSigniLicantDigits]]arepresent,thena. LetresultbeToRawPrecision(x,numberFormat.[[MinimumSigniLicantDigits]],numberFormat.[[MaximumSigniLicantDigits]]).

3. Else,a. LetresultbeToRawFixed(x,numberFormat.[[MinimumIntegerDigits]],numberFormat.[[MinimumFractionDigits]],numberFormat.[[MaximumFractionDigits]]).

4. Returnresult.

ThePartitionNumberPatternabstractoperationiscalledwithargumentsnumberFormat(whichmustbeanobjectinitializedasaNumberFormat)andx(whichmustbeaNumbervalue),interpretsxasanumericvalue,andcreatesthecorrespondingpartsaccordingtotheeffectivelocaleandtheformattingoptionsofnumberFormat.Thefollowingstepsaretaken:

11.1.5 FormatNumberToString(numberFormat,x)

11.1.6 PartitionNumberPattern(numberFormat,x)

1. IfxisnotNaNandx<0,then:a. Letxbe-x.b. LetpatternbenumberFormat.[[NegativePattern]].

2. Else,a. LetpatternbenumberFormat.[[PositivePattern]].

3. LetresultbeanewemptyList.4. LetbeginIndexbeCall(%StringProto_indexOf%,pattern,"{",0).5. LetendIndexbe0.6. LetnextIndexbe0.7. Letlengthbethenumberofcodeunitsinpattern.8. RepeatwhilebeginIndexisanintegerindexintopattern:

a. SetendIndextoCall(%StringProto_indexOf%,pattern,"}",beginIndex)

b. Assert:endIndexisgreaterthanthanbeginIndex.c. IfbeginIndexisgreaterthannextIndex,then:

i. LetliteralbeasubstringofpatternfrompositionnextIndex,inclusive,topositionbeginIndex,exclusive.

ii. AppendanewRecord{[[Type]]:"literal",[[Value]]:literal}asthelastelementofresult.

d. LetpbethesubstringofpatternfrompositionbeginIndex,exclusive,topositionendIndex,exclusive.

e. Ifpisequal"number",then:i. IfxisNaN,

1. LetnbeanILDStringvalueindicatingtheNaNvalue.

2. AppendanewRecord{[[Type]]:"nan",[[Value]]:n}asthelastelementofresult.

ii. ElseifisFinite(x)isfalse,1. LetnbeanILDStringvalueindicatinginLinity.2. AppendanewRecord{[[Type]]:"in9inity",[[Value]]:n}asthelastelementofresult.

iii. Else,1. IfnumberFormat.[[Style]]is"percent",letxbe







100×x.2. LetnbeFormatNumberToString(numberFormat,x).

3. IfthenumberFormat.[[NumberingSystem]]matchesoneofthevaluesinthe"NumberingSystem"columnofTable3below,thena. Letdigitsbeanarraywhose10StringvaluedelementsaretheUTF-16stringrepresentationsofthe10digitsspeciLiedinthe"Digits"columnofthematchingrowinTable3.

b. Replaceeachdigitinnwiththevalueofdigits[digit].

4. Elseuseanimplementationdependentalgorithmtomapntotheappropriaterepresentationofninthegivennumberingsystem.

5. LetdecimalSepIndexbeCall(%StringProto_indexOf%,n,".",0).

6. IfdecimalSepIndex>0,then:a. Letintegerbethesubstringofnfromposition0,inclusive,topositiondecimalSepIndex,exclusive.

b. LetfractionbethesubstringofnfrompositiondecimalSepIndex,exclusive,totheendofn.

7. Else:a. Letintegerben.b. Letfractionbeunde9ined.

8. IfthenumberFormat.[[UseGrouping]]istrue,a. LetgroupSepSymbolbetheILNDStringrepresentingthegroupingseparator.

b. LetgroupsbeaListwhoseelementsare,in



lefttorightorder,thesubstringsdeLinedbyILNDsetoflocationswithintheinteger.

c. Assert:ThenumberofelementsingroupsListisgreaterthan0.

d. Repeat,whilegroupsListisnotempty:i. RemovetheLirstelementfromgroupsandletintegerGroupbethevalueofthatelement.

ii. AppendanewRecord{[[Type]]:"integer",[[Value]]:integerGroup}asthelastelementofresult.

iii. IfgroupsListisnotempty,then:i. AppendanewRecord{[[Type]]:"group",[[Value]]:groupSepSymbol}asthelastelementofresult.

9. Else,a. AppendanewRecord{[[Type]]:"integer",[[Value]]:integer}asthelastelementofresult.

10. Iffractionisnotunde9ined,then:a. LetdecimalSepSymbolbetheILNDStringrepresentingthedecimalseparator.

b. AppendanewRecord{[[Type]]:"decimal",[[Value]]:decimalSepSymbol}asthelastelementofresult.

c. AppendanewRecord{[[Type]]:"fraction",[[Value]]:fraction}asthelastelementofresult.

f. Elseifpisequal"plusSign",then:i. LetplusSignSymbolbetheILNDStringrepresentingtheplussign.

ii. AppendanewRecord{[[Type]]:"plusSign",










[[Value]]:plusSignSymbol}asthelastelementofresult.

g. Elseifpisequal"minusSign",then:i. LetminusSignSymbolbetheILNDStringrepresentingtheminussign.

ii. AppendanewRecord{[[Type]]:"minusSign",[[Value]]:minusSignSymbol}asthelastelementofresult.

h. Elseifpisequal"percentSign"andnumberFormat.[[Style]]is"percent",then:i. LetpercentSignSymbolbetheILNDStringrepresentingthepercentsign.

ii. AppendanewRecord{[[Type]]:"percentSign",[[Value]]:percentSignSymbol}asthelastelementofresult.

i. Elseifpisequal"currency"andnumberFormat.[[Style]]is"currency",then:i. LetcurrencybenumberFormat.[[Currency]].ii. Assert:numberFormat.[[CurrencyDisplay]]is"code","symbol"or"name".

iii. IfnumberFormat.[[CurrencyDisplay]]is"code",then1. Letcdbecurrency.

iv. ElseifnumberFormat.[[CurrencyDisplay]]is"symbol",then1. LetcdbeanILDstringrepresentingcurrencyinshortform.Iftheimplementationdoesnothavesucharepresentationofcurrency,usecurrencyitself.

v. ElseifnumberFormat.[[CurrencyDisplay]]is"name",then1. LetcdbeanILDstringrepresentingcurrencyinlongform.Iftheimplementationdoesnothavesucharepresentationofcurrency,thenuse



currencyitself.vi. AppendanewRecord{[[Type]]:"currency",

[[Value]]:cd}asthelastelementofresult.j. Else,

i. LetliteralbethesubstringofpatternfrompositionbeginIndex,inclusive,topositionendIndex,inclusive.

ii. AppendanewRecord{[[Type]]:"literal",[[Value]]:literal}asthelastelementofresult.

k. SetnextIndextoendIndex+1.l. SetbeginIndextoCall(%StringProto_indexOf%,pattern,"{",nextIndex)

9. IfnextIndexislessthanlength,then:a. LetliteralbethesubstringofpatternfrompositionnextIndex,inclusive,topositionlength,exclusive.

b. AppendanewRecord{[[Type]]:"literal",[[Value]]:literal}asthelastelementofresult.

10. Returnresult.

Table3:Numberingsystemswithsimpledigitmappings

NumberingSystem

Digits

arab U+0660toU+0669

arabext U+06F0toU+06F9

bali U+1B50toU+1B59

beng U+09E6toU+09EF

deva U+0966toU+096F

fullwide U+FF10toU+FF19

gujr U+0AE6toU+0AEF

guru U+0A66toU+0A6F





hanidec U+3007,U+4E00,U+4E8C,U+4E09,U+56DB,U+4E94,U+516D,U+4E03,U+516B,U+4E5D

khmr U+17E0toU+17E9

knda U+0CE6toU+0CEF

laoo U+0ED0toU+0ED9

latn U+0030toU+0039

limb U+1946toU+194F

mlym U+0D66toU+0D6F

mong U+1810toU+1819

mymr U+1040toU+1049

orya U+0B66toU+0B6F

tamldec U+0BE6toU+0BEF

telu U+0C66toU+0C6F

thai U+0E50toU+0E59

tibt U+0F20toU+0F29

NOTE1 ThecomputationsrelyonStringvaluesandlocationswithinnumericstringsthataredependentupontheimplementationandtheeffectivelocaleofnumberFormat(“ILD")orupontheimplementation,theeffectivelocale,andthenumberingsystemofnumberFormat(“ILND").TheILDandILNDStringsmentioned,otherthanthoseforcurrencynames,mustnotcontainanycharactersintheGeneralCategory“Number,decimaldigit"asspeciLiedbytheUnicode

Standard.

NOTE2 ItisrecommendedthatimplementationsusethelocaleprovidedbytheCommonLocaleDataRepository(availableathttp://cldr.unicode.org/).

TheFormatNumberabstractoperationiscalledwithargumentsnumberFormat(whichmustbeanobjectinitializedasaNumberFormat)andx(whichmustbeaNumbervalue),andperformsthefollowingsteps:

1. Letpartsbe?PartitionNumberPattern(numberFormat,x).2. LetresultbetheemptyString.3. Foreachpartinparts,do:

a. SetresulttoaStringvalueproducedbyconcatenatingresultandpart.[[Value]].

4. Returnresult.

TheFormatNumberToPartsabstractoperationiscalledwithargumentsnumberFormat(whichmustbeanobjectinitializedasaNumberFormat)andx(whichmustbeaNumbervalue),andperformsthefollowingsteps:

1. Letpartsbe?PartitionNumberPattern(numberFormat,x).2. LetresultbeArrayCreate(0).3. Letnbe0.4. Foreachpartinparts,do:

a. LetObeObjectCreate(%ObjectPrototype%).b. Perform?CreateDataPropertyOrThrow(O,"type",part.[[Type]]).

11.1.7 FormatNumber(numberFormat,x)

11.1.8 FormatNumberToParts(numberFormat,x)


https://tc39.github.io/ecma262/#sec-arraycreate



https://tc39.github.io/ecma262/#sec-createdatapropertyorthrow

c. Perform?CreateDataPropertyOrThrow(O,"value",part.[[Value]]).

d. Perform?CreateDataPropertyOrThrow(result,?ToString(n),O).

e. Incrementnby1.5. Returnresult.

WhentheToRawPrecisionabstractoperationiscalledwithargumentsx(whichmustbeaLinitenon-negativenumber),minPrecision,andmaxPrecision(bothmustbeintegersbetween1and21),thefollowingstepsaretaken:

1. LetpbemaxPrecision.2. Ifx=0,then

a. LetmbetheStringconsistingofpoccurrencesofthecharacter"0".

b. Letebe0.3. Else,

a. Leteandnbeintegerssuchthat10p–1≤n<10pandforwhichtheexactmathematicalvalueofn×10e–p+1–xisasclosetozeroaspossible.Iftherearetwosuchsetsofeandn,picktheeandnforwhichn×10e–p+1islarger.

b. LetmbetheStringconsistingofthedigitsofthedecimalrepresentationofn(inorder,withnoleadingzeroes).

4. Ife≥p,thena. Returntheconcatenationofmande-p+1occurrencesofthecharacter"0".

5. Ife=p-1,thena. Returnm.

6. Ife≥0,then

11.1.9 ToRawPrecision(x,minPrecision,maxPrecision)




a. LetmbetheconcatenationoftheLirste+1charactersofm,thecharacter".",andtheremainingp–(e+1)charactersofm.

7. Ife<0,thena. LetmbetheconcatenationoftheString"0.",–(e+1)occurrencesofthecharacter"0",andthestringm.

8. Ifmcontainsthecharacter".",andmaxPrecision>minPrecision,thena. LetcutbemaxPrecision–minPrecision.b. Repeatwhilecut>0andthelastcharacterofmis"0":

i. Removethelastcharacterfromm.ii. Decreasecutby1.

c. Ifthelastcharacterofmis".",theni. Removethelastcharacterfromm.

9. Returnm.

WhentheToRawFixedabstractoperationiscalledwithargumentsx(whichmustbeaLinitenon-negativenumber),minInteger(whichmustbeanintegerbetween1and21),minFraction,andmaxFraction(whichmustbeintegersbetween0and20),thefollowingstepsaretaken:

1. LetfbemaxFraction.2. Letnbeanintegerforwhichtheexactmathematicalvalueofn÷10f–xisasclosetozeroaspossible.Iftherearetwosuchn,pickthelargern.

3. Ifn=0,letmbetheString"0".Otherwise,letmbetheStringconsistingofthedigitsofthedecimalrepresentationofn(inorder,withnoleadingzeroes).

4. Iff≠0,thena. Letkbethenumberofcharactersinm.

11.1.10 ToRawFixed(x,minInteger,minFraction,maxFraction)

b. Ifk≤f,theni. LetzbetheStringconsistingoff+1–koccurrencesofthecharacter"0".

ii. LetmbetheconcatenationofStringszandm.iii. Letkbef+1.

c. LetabetheLirstk–fcharactersofm,andletbbetheremainingfcharactersofm.

d. LetmbetheconcatenationofthethreeStringsa,".",andb.

e. Letintbethenumberofcharactersina.5. Else,letintbethenumberofcharactersinm.6. LetcutbemaxFraction–minFraction.7. Repeatwhilecut>0andthelastcharacterofmis"0":

a. Removethelastcharacterfromm.b. Decreasecutby1.

8. Ifthelastcharacterofmis".",thena. Removethelastcharacterfromm.

9. Ifint<minInteger,thena. LetzbetheStringconsistingofminInteger–intoccurrencesofthecharacter"0".

b. LetmbetheconcatenationofStringszandm.10. Returnm.

TheUnwrapNumberFormatabstractoperationgetstheunderlyingNumberFormatoperationforvariousmethodswhichimplementECMA-402v1semanticsforsupportinginitializingexistingIntlobjects.

NORMATIVEOPTIONAL

1. IfType(nf)isObjectandnfdoesnothavean[[InitializedNumberFormat]]internalslotand

11.1.11 UnwrapNumberFormat(nf)


?InstanceofOperator(nf,%NumberFormat%)isequaltrue,thena. LetnfbeGet(nf,Intl.[[FallbackSymbol]]).

2. IfType(nf)isnotObjectornfdoesnothavean[[InitializedNumberFormat]]internalslot,thena. ThrowaTypeErrorexception.

3. Returnnf.

TheNumberFormatconstructoristhe%NumberFormat%intrinsicobjectandastandardbuilt-inpropertyoftheIntlobject.BehaviourcommontoallserviceconstructorpropertiesoftheIntlobjectisspeciLiedin9.1.

WhentheIntl.NumberFormatfunctioniscalledwithoptionalargumentslocalesandoptions,thefollowingstepsaretaken:


2. LetnumberFormatbe?OrdinaryCreateFromConstructor(newTarget,"%NumberFormatPrototype%",«[[InitializedIntlObject]],[[InitializedNumberFormat]],[[Locale]],[[NumberingSystem]],[[Style]],[[Currency]],[[CurrencyDisplay]],[[MinimumIntegerDigits]],[[MinimumFractionDigits]],[[MaximumFractionDigits]],[[MinimumSigniLicantDigits]],[[MaximumSigniLicantDigits]],[[UseGrouping]],

11.2 TheIntl.NumberFormatConstructor

11.2.1 Intl.NumberFormat([locales[,options]])

https://tc39.github.io/ecma262/#sec-instanceofoperator





[[PositivePattern]],[[NegativePattern]],[[BoundFormat]]»).3. Perform?InitializeNumberFormat(numberFormat,locales,options).

NORMATIVEOPTIONAL

4. Letthisbethethisvalue.5. IfNewTargetisunde9inedand?InstanceofOperator(this,%NumberFormat%),thena. Perform?DeLineOwnPropertyOrThrow(this,Intl.[[FallbackSymbol]],{[[Value]]:numberFormat,[[Writable]]:false,[[Enumerable]]:false,[[ConLigurable]]:false}).

b. Returnthis.

6. ReturnnumberFormat.

TheIntl.NumberFormatconstructorhasthefollowingproperties:

ThevalueofIntl.NumberFormat.prototypeis%NumberFormatPrototype%.


11.3 PropertiesoftheIntl.NumberFormatConstructor

11.3.1 Intl.NumberFormat.prototype

11.3.2 Intl.NumberFormat.supportedLocalesOf(locales[,options])


WhenthesupportedLocalesOfmethodiscalledwithargumentslocalesandoptions,thefollowingstepsaretaken:

1. LetavailableLocalesbe%NumberFormat%.[[AvailableLocales]].

2. LetrequestedLocalesbe?CanonicalizeLocaleList(locales).3. Return?SupportedLocales(availableLocales,requestedLocales,options).


Thevalueofthe[[AvailableLocales]]internalslotisimplementationdeLinedwithintheconstraintsdescribedin9.1.

Thevalueofthe[[RelevantExtensionKeys]]internalslotis«"nu"».

NOTE1 UnicodeTechnicalStandard35describestwolocaleextensionkeysthatarerelevanttonumberformatting,"nu"fornumberingsystemand"cu"forcurrency.Intl.NumberFormat,however,requiresthatthecurrencyofacurrencyformatisspeciLiedthroughthecurrencypropertyintheoptionsobjects.

Thevalueofthe[[LocaleData]]internalslotisimplementationdeLinedwithintheconstraintsdescribedin9.1andthefollowingadditionalconstraints:

Thearraythatisthevalueofthe"nu"propertyofanylocalepropertyof[[LocaleData]]mustnotincludethevalues"native","traditio",or"Linance".[[LocaleData]][locale]musthaveapatternspropertyforalllocalevalues.Thevalueofthispropertymustbeanobject,

11.3.3 Internalslots

whichmusthavepropertieswiththenamesofthethreenumberformatstyles:"decimal","percent",and"currency".EachofthesepropertiesinturnmustbeanobjectwiththepropertiespositivePatternandnegativePattern.Thevalueofthesepropertiesmustbestringvaluesthatmustcontainthesubstring"{number}"andmaycontainthesubstrings"{plusSign}",and"{minusSign}";thevalueswithinthepercentpropertymustalsocontainthesubstring"{percentSign}";thevalueswithinthecurrencypropertymustalsocontainthesubstring"{currency}".ThepatternstringsmustnotcontainanycharactersintheGeneralCategory“Number,decimaldigit"asspeciLiedbytheUnicodeStandard.

NOTE2 ItisrecommendedthatimplementationsusethelocaledataprovidedbytheCommonLocaleDataRepository(availableathttp://cldr.unicode.org/).

TheIntl.NumberFormatprototypeobjectistheintrinsicobject%NumberFormatPrototype%.TheIntl.NumberFormatprototypeobjectisitselfanIntl.NumberFormatinstanceasspeciLiedin11.5,whoseinternalslotsaresetasifithadbeenconstructedbytheexpressionConstruct(%NumberFormat%,«»,%Object%).

Inthefollowingdescriptionsoffunctionsthatarepropertiesor[[Get]]attributesofpropertiesof%NumberFormatPrototype%,thephrase"thisNumberFormatobject"referstotheobjectthatisthethisvaluefortheinvocationofthefunction;aTypeErrorexceptionisthrownifthethisvalueisnotanobjectoranobjectthatdoesnothavean[[InitializedNumberFormat]]internalslotwithvaluetrue.

11.4 PropertiesoftheIntl.NumberFormatPrototypeObject




TheinitialvalueofIntl.NumberFormat.prototype.constructoristheintrinsicobject%NumberFormat%.



Intl.NumberFormat.prototype.formatisanaccessorpropertywhosesetaccessorfunctionisunde9ined.Itsgetaccessorfunctionperformsthefollowingsteps:

1. Letnfbethisvalue.2. IfType(nf)isnotObject,throwaTypeErrorexception.3. Letnfbe?UnwrapNumberFormat(nf);4. Ifnf.[[BoundFormat]]isunde9ined,then

a. LetFbeanewbuilt-infunctionobjectasdeLinedinNumberFormatFunctions(11.1.4).

b. LetbfbeBoundFunctionCreate(F,nf,«»).c. Perform!DeLinePropertyOrThrow(bf,"length",PropertyDescriptor{[[Value]]:1,[[Writable]]:false,[[Enumerable]]:false,[[ConLigurable]]:true}).

d. Setnf.[[BoundFormat]]tobf.5. Returnnf.[[BoundFormat]].

11.4.1 Intl.NumberFormat.prototype.constructor

11.4.2 Intl.NumberFormat.prototype[@@toStringTag]

11.4.3 getIntl.NumberFormat.prototype.format




Thisfunctionprovidesaccesstothelocaleandformattingoptionscomputedduringinitializationoftheobject.ThisfunctioninitiallyinvokestheinternalalgorithmUnwrapNumberFormattogetthe%NumberFormat%objectonwhichtooperate.

ThefunctionreturnsanewobjectwhosepropertiesandattributesaresetasifconstructedbyanobjectliteralassigningtoeachofthefollowingpropertiesthevalueofthecorrespondinginternalslotofthisNumberFormatobject(see11.5):locale,numberingSystem,style,currency,currencyDisplay,minimumIntegerDigits,minimumFractionDigits,maximumFractionDigits,minimumSigniLicantDigits,maximumSigniLicantDigits,anduseGrouping.Propertieswhosecorrespondinginternalslotshavethevalueunde9inedarenotassigned.

Intl.NumberFormatinstancesinheritpropertiesfrom%NumberFormatPrototype%.

Intl.NumberFormatinstancesandotherobjectsthathavebeensuccessfullyinitializedasaNumberFormathave[[InitializedIntlObject]]and[[InitializedNumberFormat]]internalslotswhosevaluesaretrue.

ObjectsthathavebeensuccessfullyinitializedasaNumberFormatobjectalsohaveseveralinternalslotsthatarecomputedbytheconstructor:

[[Locale]]isaStringvaluewiththelanguagetagofthelocale

11.4.4 Intl.NumberFormat.prototype.resolvedOptions()

11.5 PropertiesofIntl.NumberFormatInstances

whoselocalizationisusedforformatting.[[NumberingSystem]]isaStringvaluewiththe“type”giveninUnicodeTechnicalStandard35forthenumberingsystemusedforformatting.[[Style]]isoneoftheStringvalues"decimal","currency",or"percent",identifyingthenumberformatstyleused.[[Currency]]isaStringvaluewiththecurrencycodeidentifyingthecurrencytobeusedifformattingwiththe"currency"style.Itisonlyusedwhen[[Style]]hasthevalue"currency".[[CurrencyDisplay]]isoneoftheStringvalues"code","symbol",or"name",specifyingwhethertodisplaythecurrencyasanISO4217alphabeticcurrencycode,alocalizedcurrencysymbol,oralocalizedcurrencynameifformattingwiththe"currency"style.Itisonlyusedwhen[[Style]]hasthevalue"currency".[[MinimumIntegerDigits]]isanon-negativeintegerNumbervalueindicatingtheminimumintegerdigitstobeused.Numberswillbepaddedwithleadingzeroesifnecessary.[[MinimumFractionDigits]]and[[MaximumFractionDigits]]arenon-negativeintegerNumbervaluesindicatingtheminimumandmaximumfractiondigitstobeused.Numberswillberoundedorpaddedwithtrailingzeroesifnecessary.[[MinimumSigniLicantDigits]]and[[MaximumSigniLicantDigits]]arepositiveintegerNumbervaluesindicatingtheminimumandmaximumfractiondigitstobeshown.Eithernoneorbothofthesepropertiesarepresent;iftheyare,theyoverrideminimumandmaximumintegerandfractiondigits–theformatteruseshowevermanyintegerandfractiondigitsarerequiredtodisplaythespeciLiednumberofsigniLicantdigits.[[UseGrouping]]isaBooleanvalueindicatingwhetheragroupingseparatorshouldbeused.[[PositivePattern]]and[[NegativePattern]]areStringvaluesas

describedin11.3.3.

Finally,objectsthathavebeensuccessfullyinitializedasaNumberFormathavea[[BoundFormat]]internalslotthatcachesthefunctionreturnedbytheformataccessor(11.4.3).

SeveralDateTimeFormatalgorithmsusevaluesfromthefollowingtable,whichprovidesinternalslots,propertynamesandallowablevaluesforthecomponentsofdateandtimeformats:

Table4:Componentsofdateandtimeformats

InternalSlot Property Values

[[Weekday]] "weekday" "narrow","short","long"

[[Era]] "era" "narrow","short","long"

[[Year]] "year" "2-digit","numeric"

[[Month]] "month" "2-digit","numeric","narrow","short","long"

[[Day]] "day" "2-digit","numeric"

[[Hour]] "hour" "2-digit","numeric"

[[Minute]] "minute" "2-digit","numeric"

[[Second]] "second" "2-digit","numeric"

12 DateTimeFormatObjects

12.1 AbstractOperationsForDateTimeFormatObjects

[[TimeZoneName]] "timeZoneName" "short","long"

TheabstractoperationInitializeDateTimeFormatacceptstheargumentsdateTimeFormat(whichmustbeanobject),locales,andoptions.ItinitializesdateTimeFormatasaDateTimeFormatobject.Thisabstractoperationfunctionsasfollows:

1. IfdateTimeFormat.[[InitializedIntlObject]]istrue,throwaTypeErrorexception.

2. SetdateTimeFormat.[[InitializedIntlObject]]totrue.3. LetrequestedLocalesbe?CanonicalizeLocaleList(locales).4. Letoptionsbe?ToDateTimeOptions(options,"any","date").5. LetoptbeanewRecord.6. Letmatcherbe?GetOption(options,"localeMatcher","string",«"lookup","best9it"»,"best9it").

7. Setopt.[[localeMatcher]]tomatcher.8. LetlocaleDatabe%DateTimeFormat%.[[LocaleData]].9. LetrbeResolveLocale(%DateTimeFormat%.[[AvailableLocales]],requestedLocales,opt,%DateTimeFormat%.[[RelevantExtensionKeys]],localeData).

10. SetdateTimeFormat.[[Locale]]tor.[[locale]].11. SetdateTimeFormat.[[Calendar]]tor.[[ca]].12. SetdateTimeFormat.[[NumberingSystem]]tor.[[nu]].13. LetdataLocaleber.[[dataLocale]].14. Lettzbe?Get(options,"timeZone").15. Iftzisnotunde9ined,then

a. Lettzbe?ToString(tz).b. IftheresultofIsValidTimeZoneName(tz)isfalse,then

i. ThrowaRangeErrorexception.c. LettzbeCanonicalizeTimeZoneName(tz).

12.1.1 InitializeDateTimeFormat(dateTimeFormat,locales,options)




16. Else,a. LettzbeDefaultTimeZone().

17. SetdateTimeFormat.[[TimeZone]]totz.18. LetoptbeanewRecord.19. ForeachrowofTable4,excepttheheaderrow,do:

a. LetpropbethenamegiveninthePropertycolumnoftherow.

b. Letvaluebe?GetOption(options,prop,"string",«thestringsgivenintheValuescolumnoftherow»,unde9ined).

c. Setopt.[[<prop>]]tovalue.20. LetdataLocaleDatabeGet(localeData,dataLocale).21. LetformatsbeGet(dataLocaleData,"formats").22. Letmatcherbe?GetOption(options,"formatMatcher",

"string",«"basic","best9it"»,"best9it").23. Ifmatcheris"basic",then

a. LetbestFormatbeBasicFormatMatcher(opt,formats).24. Else,

a. LetbestFormatbeBestFitFormatMatcher(opt,formats).25. ForeachrowinTable4,excepttheheaderrow,do

a. LetpropbethenamegiveninthePropertycolumnoftherow.

b. LetpbeGet(bestFormat,prop).c. Ifpnotunde9ined,then

i. SetdateTimeFormat'sinternalslotwhosenameistheInternalSlotcolumnoftherowtop.

26. Lethr12be?GetOption(options,"hour12","boolean",unde9ined,unde9ined).

27. IfdateTimeFormathasaninternalslot[[Hour]],thena. Ifhr12isunde9ined,then

i. Lethr12beGet(dataLocaleData,"hour12").b. SetdateTimeFormat.[[Hour12]]tohr12.c. Ifhr12istrue,then






i. LethourNo0beGet(dataLocaleData,"hourNo0").ii. SetdateTimeFormat.[[HourNo0]]tohourNo0.iii. LetpatternbeGet(bestFormat,"pattern12").

d. Else,i. LetpatternbeGet(bestFormat,"pattern").

28. Else,a. LetpatternbeGet(bestFormat,"pattern").

29. SetdateTimeFormat.[[Pattern]]topattern.30. SetdateTimeFormat.[[BoundFormat]]tounde9ined.31. SetdateTimeFormat.[[InitializedDateTimeFormat]]totrue.32. ReturndateTimeFormat.

WhentheToDateTimeOptionsabstractoperationiscalledwithargumentsoptions,required,anddefaults,thefollowingstepsaretaken:

1. Ifoptionsisunde9ined,letoptionsbenull;otherwiseletoptionsbe?ToObject(options).

2. LetoptionsbeObjectCreate(options).3. LetneedDefaultsbetrue.4. Ifrequiredis"date"or"any",

a. Foreachofthepropertynames"weekday","year","month","day":i. Letpropbethepropertyname.ii. Letvaluebe?Get(options,prop).iii. Ifvalueisnotunde9ined,letneedDefaultsbefalse.

5. Ifrequiredis"time"or"any",a. Foreachofthepropertynames"hour","minute","second":i. Letpropbethepropertyname.ii. Letvaluebe?Get(options,prop).

12.1.2 ToDateTimeOptions(options,required,defaults)









iii. Ifvalueisnotunde9ined,letneedDefaultsbefalse.6. IfneedDefaultsistrueanddefaultsiseither"date"or"all",thena. Foreachofthepropertynames"year","month","day":

i. Perform?CreateDataPropertyOrThrow(options,prop,"numeric").

7. IfneedDefaultsistrueanddefaultsiseither"time"or"all",thena. Foreachofthepropertynames"hour","minute","second":i. Perform?CreateDataPropertyOrThrow(options,prop,"numeric").

8. Returnoptions.

WhentheBasicFormatMatcherabstractoperationiscalledwithtwoargumentsoptionsandformats,thefollowingstepsaretaken:

1. LetremovalPenaltybe120.2. LetadditionPenaltybe20.3. LetlongLessPenaltybe8.4. LetlongMorePenaltybe6.5. LetshortLessPenaltybe6.6. LetshortMorePenaltybe3.7. LetbestScorebe-In9inity.8. LetbestFormatbeunde9ined.9. Letkbe0.10. Assert:formatsisanArrayobject.11. LetlenbeGet(formats,"length").12. Repeatwhilek<len:

a. LetformatbeGet(formats,ToString(k)).b. Letscorebe0.

12.1.3 BasicFormatMatcher(options,formats)






c. ForeachpropertyshowninTable4:i. LetoptionsPropbeoptions.[[<property>]].ii. LetformatPropbeGet(format,property).iii. IfoptionsPropisunde9inedandformatPropisnot

unde9ined,thendecreasescorebyadditionPenalty.iv. ElseifoptionsPropisnotunde9inedandformatProp

isunde9ined,thendecreasescorebyremovalPenalty.v. ElseifoptionsProp≠formatProp,

1. Letvaluesbethearray["2-digit","numeric","narrow","short","long"].

2. LetoptionsPropIndexbetheindexofoptionsPropwithinvalues.

3. LetformatPropIndexbetheindexofformatPropwithinvalues.

4. Letdeltabemax(min(formatPropIndex-optionsPropIndex,2),-2).

5. Ifdelta=2,decreasescorebylongMorePenalty.6. Elseifdelta=1,decreasescorebyshortMorePenalty.

7. Elseifdelta=-1,decreasescorebyshortLessPenalty.

8. Elseifdelta=-2,decreasescorebylongLessPenalty.

d. Ifscore>bestScore,i. LetbestScorebescore.ii. LetbestFormatbeformat.

e. Increasekby1.13. ReturnbestFormat.

WhentheBestFitFormatMatcherabstractoperationiscalledwithtwoargumentsoptionsandformats,itperformsimplementation

12.1.4 BestFitFormatMatcher(options,formats)




dependentsteps,whichshouldreturnasetofcomponentrepresentationsthatatypicaluseroftheselectedlocalewouldperceiveasatleastasgoodastheonereturnedbyBasicFormatMatcher.

ADateTimeformatfunctionisananonymousbuilt-infunction.

WhenaDateTimeformatfunctioniscalledwithoptionalargumentdate,thefollowingstepsaretaken:

1. Letdtfbethethisvalue.2. Assert:Type(dtf)isObjectanddtf.[[InitializedDateTimeFormat]]istrue.

3. Ifdateisnotprovidedorisunde9ined,thena. LetxbeCall(%Date_now%,unde9ined).

4. Else,a. Letxbe?ToNumber(date).

5. ReturnFormatDateTime(dtf,x).

NOTE Thefunctionreturnedby[[Get]]isboundtothisDateTimeFormatobjectsothatitcanbepasseddirectlytoArray.prototype.maporotherfunctions.

ThelengthpropertyofaDateTimeformatfunctionis1.

ThePartitionDateTimePatternabstractoperationiscalledwithargumentsdateTimeFormat(whichmustbeanobjectinitializedasaDateTimeFormat)andx(whichmustbeaNumbervalue),interpretsxasatimevalueasspeciLiedinES2015,20.3.1.1,andcreatesthe

12.1.5 DateTimeFormatFunctions

12.1.6 PartitionDateTimePattern(dateTimeFormat,x)




https://tc39.github.io/ecma262/#sec-time-values-and-time-range

https://tc39.github.io/ecma262/#sec-time-values-and-time-range

correspondingpartsaccordingtotheeffectivelocaleandtheformattingoptionsofdateTimeFormat.Thefollowingstepsaretaken:

1. IfxisnotaLiniteNumber,throwaRangeErrorexception.2. LetlocalebedateTimeFormat.[[Locale]].3. LetnfLocalebeCreateArrayFromList(«locale»).4. LetnfOptionsbeObjectCreate(%ObjectPrototype%).5. Perform!CreateDataPropertyOrThrow(nfOptions,

"useGrouping",false).6. Letnfbe?Construct(%NumberFormat%,«nfLocale,nfOptions»).

7. Letnf2OptionsbeObjectCreate(%ObjectPrototype%).8. Perform!CreateDataPropertyOrThrow(nf2Options,

"minimumIntegerDigits",2).9. Perform!CreateDataPropertyOrThrow(nf2Options,

"useGrouping",false).10. Letnf2be?Construct(%NumberFormat%,«nfLocale,

nf2Options»).11. LettmbeToLocalTime(x,dateTimeFormat.[[Calendar]],

dateTimeFormat.[[TimeZone]]).12. LetpatternbedateTimeFormat.[[Pattern]].13. LetresultbeanewemptyList.14. LetbeginIndexbeCall(%StringProto_indexOf%,pattern,"{",0).15. LetendIndexbe0.16. LetnextIndexbe0.17. Letlengthbethenumberofcodeunitsinpattern.18. RepeatwhilebeginIndexisanintegerindexintopattern:

a. SetendIndextoCall(%StringProto_indexOf%,pattern,"}",beginIndex)

b. IfendIndex=-1,thrownewErrorexception.c. IfbeginIndexisgreaterthannextIndex,then:

i. Letliteralbeasubstringofpatternfromposition














nextIndex,inclusive,topositionbeginIndex,exclusive.ii. Addnewpartrecord{[[Type]]:"literal",[[Value]]:literal}asanewelementofthelistresult.

d. LetpbethesubstringofpatternfrompositionbeginIndex,exclusive,topositionendIndex,exclusive.

e. IfpmatchesaPropertycolumnoftherowinTable4,then:i. LetfbethevalueofdateTimeFormat'sinternalslotwhosenameistheInternalSlotcolumnofthematchingrow.

ii. Letvbethevalueoftm'sLieldwhosenameistheInternalSlotcolumnofthematchingrow.

iii. Ifpis"year"andv≤0,letvbe1-v.iv. Ifpis"month",increasevby1.v. Ifpis"hour"anddateTimeFormat.[[Hour12]]istrue,then1. Letvbevmodulo12.2. Ifvis0anddateTimeFormat.[[HourNo0]]istrue,letvbe12.

vi. Iffis"numeric",then1. LetfvbeFormatNumber(nf,v).

vii. Elseiffis"2-digit",then1. LetfvbeFormatNumber(nf2,v).2. Ifthelengthpropertyoffvisgreaterthan2,letfvbethesubstringoffvcontainingthelasttwocharacters.

viii. Elseiffis"narrow","short",or"long",thenletfvbeaStringvaluerepresentingfinthedesiredform;theStringvaluedependsupontheimplementationandtheeffectivelocaleandcalendarofdateTimeFormat.Ifpis"month",thentheStringvaluemayalsodependonwhetherdateTimeFormathasa[[Day]]internalslot.Ifpis"timeZoneName",thentheStringvaluemayalsodependonthevalueofthe[[inDST]]


Lieldoftm.Ifpis"era",thentheStringvaluemayalsodependonwhetherdateTimeFormathasa[[Era]]internalslotandiftheimplementationdoesnothavealocalizedrepresentationoff,thenusefitself.

ix. Addnewpartrecord{[[Type]]:p,[[Value]]:fv}asanewelementofthelistresult.

f. Elseifpisequal"ampm",then:i. Letvbetm.[[hour]].ii. Ifvisgreaterthan11,then:

1. LetfvbeanimplementationandlocaledependentStringvaluerepresenting"postmeridiem";

iii. Else,1. LetfvbeanimplementationandlocaledependentStringvaluerepresenting"antemeridiem".

iv. Addnewpartrecord{[[Type]]:"dayPeriod",[[Value]]:fv}asanewelementofthelistresult.

v. LetliteralbethesubstringofpatternfrompositionbeginIndex,inclusive,topositionendIndex,inclusive.

vi. Addnewpartrecord{[[Type]]:"literal",[[Value]]:literal}asanewelementofthelistresult.

g. SetnextIndextoendIndex+1.h. SetbeginIndextoCall(%StringProto_indexOf%,pattern,"}",nextIndex)

19. IfnextIndexislessthanlength,then:a. LetliteralbethesubstringofpatternfrompositionnextIndex,exclusive,topositionlength,exclusive.

b. Addnewpartrecord{[[Type]]:"literal",[[Value]]:literal}asanewelementofthelistresult.

20. Returnresult.

NOTE1 Itisrecommendedthatimplementationsusethe


localeandcalendardependentstringsprovidedbytheCommonLocaleDataRepository(availableathttp://cldr.unicode.org/),anduseCLDR"abbreviated"stringsforDateTimeFormat"short"strings,andCLDR"wide"stringsforDateTimeFormat"long"strings.

NOTE2 ItisrecommendedthatimplementationsusethetimezoneinformationoftheIANATimeZoneDatabase.

TheFormatDateTimeabstractoperationiscalledwithargumentsdateTimeFormat(whichmustbeanobjectinitializedasaDateTimeFormat)andx(whichmustbeaNumbervalue),andperformsthefollowingsteps:

1. Letpartsbe?PartitionDateTimePattern(dateTimeFormat,x).2. LetresultbetheemptyString.3. Foreachpartinparts,do:

a. SetresulttoaStringvalueproducedbyconcatenatingresultandpart.[[Value]].

4. Returnresult.

TheFormatDateTimeToPartsabstractoperationiscalledwithargumentsdateTimeFormat(whichmustbeanobjectinitializedasaDateTimeFormat)andx(whichmustbeaNumbervalue),andperformsthefollowingsteps:

1. Letpartsbe?PartitionDateTimePattern(dateTimeFormat,x).2. LetresultbeArrayCreate(0).3. Letnbe0.

12.1.7 FormatDateTime(dateTimeFormat,x)

12.1.8 FormatDateTimeToParts(dateTimeFormat,x)


https://tc39.github.io/ecma262/#sec-arraycreate

4. Foreachpartinparts,do:a. LetObeObjectCreate(%ObjectPrototype%).b. Perform?CreateDataPropertyOrThrow(O,"type",part.[[Type]]).

c. Perform?CreateDataPropertyOrThrow(O,"value",part.[[Value]]).

d. Perform?CreateDataProperty(result,?ToString(n),O).e. Incrementnby1.

5. Returnresult.

WhentheToLocalTimeabstractoperationiscalledwithargumentsdate,calendar,andtimeZone,thefollowingstepsaretaken:

1. ApplycalendricalcalculationsondateforthegivencalendarandtimeZonetoproduceweekday,era,year,month,day,hour,minute,second,andinDSTvalues.ThecalculationsshouldusebestavailableinformationaboutthespeciLiedcalendarandtimeZone,includingcurrentandhistoricalinformationabouttimezoneoffsetsfromUTCanddaylightsavingtimerules.Ifthecalendaris"gregory",thenthecalculationsmustmatchthealgorithmsspeciLiedinES2017,20.3.1.

2. ReturnaRecordwithLields[[weekday]],[[era]],[[year]],[[month]],[[day]],[[hour]],[[minute]],[[second]],and[[inDST]],eachwiththecorrespondingcalculatedvalue.

NOTE ItisrecommendedthatimplementationsusethetimezoneinformationoftheIANATimeZoneDatabase.

TheUnwrapDateTimeFormatabstractoperationgetstheunderlyingDateTimeFormatoperationforvariousmethodswhichimplement

12.1.9 ToLocalTime(date,calendar,timeZone)

12.1.10 UnwrapDateTimeFormat(dtf)





https://tc39.github.io/ecma262/#sec-createdataproperty


https://tc39.github.io/ecma262/#sec-overview-of-date-objects-and-definitions-of-abstract-operations


ECMA-402v1semanticsforsupportinginitializingexistingIntlobjects.

NORMATIVEOPTIONAL

2. IfType(dtf)isObjectanddtfdoesnothavean[[initializedDateTimeFormat]]internalslotand?InstanceofOperator(dtf,%DateTimeFormat%)istrue,then

3. Ifdtfdoesnothavean[[InitializedDateTimeFormat]]internalslotand?InstanceofOperator(dtf,%DateTimeFormat%)isequaltrue,thena. LetdtfbeGet(dtf,Intl.[[FallbackSymbol]]).

2. IfType(dtf)isnotObjectordtfdoesnothavean[[initializedDateTimeFormat]]internalslot,thena. ThrowaTypeErrorexception.

3. Returndtf.

TheIntl.DateTimeFormatconstructoristhe%DateTimeFormat%intrinsicobjectandastandardbuilt-inpropertyoftheIntlobject.BehaviourcommontoallserviceconstructorpropertiesoftheIntlobjectisspeciLiedin9.1.

WhentheIntl.DateTimeFormatfunctioniscalledwithoptional

13 TheIntl.DateTimeFormatConstructor

13.1 Intl.DateTimeFormat([locales[,options]])






argumentslocalesandoptions,thefollowingstepsaretaken:


2. LetdateTimeFormatbe?OrdinaryCreateFromConstructor(newTarget,"%DateTimeFormatPrototype%",«[[InitializedIntlObject]],[[InitializedDateTimeFormat]],[[Locale]],[[Calendar]],[[NumberingSystem]],[[TimeZone]],[[Weekday]],[[Era]],[[Year]],[[Month]],[[Day]],[[Hour]],[[Minute]],[[Second]],[[TimeZoneName]],[[Hour12]],[[HourNo0]],[[Pattern]],[[BoundFormat]]»).

3. Perform?InitializeDateTimeFormat(dateTimeFormat,locales,options).

NORMATIVEOPTIONAL

4. Letthisbethethisvalue.5. IfNewTargetisunde9inedand?InstanceofOperator(this,%DateTimeFormat%),thena. Perform?DeLineOwnPropertyOrThrow(this,Intl.[[FallbackSymbol]],{[[Value]]:dateTimeFormat,[[Writable]]:false,[[Enumerable]]:false,[[ConLigurable]]:false}).

b. Returnthis.

6. ReturndateTimeFormat.

14 PropertiesoftheIntl.DateTimeFormatConstructor




TheIntl.DateTimeFormatconstructorhasthefollowingproperties:

ThevalueofIntl.DateTimeFormat.prototypeis%DateTimeFormatPrototype%.


WhenthesupportedLocalesOfmethodiscalledwithargumentslocalesandoptions,thefollowingstepsaretaken:

1. LetavailableLocalesbe%DateTimeFormat%.[[AvailableLocales]].

2. LetrequestedLocalesbe?CanonicalizeLocaleList(locales).3. Return?SupportedLocales(availableLocales,requestedLocales,options).


Thevalueofthe[[AvailableLocales]]internalslotisimplementationdeLinedwithintheconstraintsdescribedin9.1.

Thevalueofthe[[RelevantExtensionKeys]]internalslotis«"ca",

14.1 Intl.DateTimeFormat.prototype

14.2 Intl.DateTimeFormat.supportedLocalesOf(locales[,options])

14.3 Internalslots

"nu"».

NOTE1 UnicodeTechnicalStandard35describesthreelocaleextensionkeysthatarerelevanttodateandtimeformatting,"ca"forcalendar,"tz"fortimezone,andimplicitly"nu"forthenumberingsystemofthenumberformatusedfornumberswithinthedateformat.DateTimeFormat,however,requiresthatthetimezoneisspeciLiedthroughthetimeZonepropertyintheoptionsobjects.

Thevalueofthe[[LocaleData]]internalslotisimplementationdeLinedwithintheconstraintsdescribedin9.1andthefollowingadditionalconstraints:

Thearraythatisthevalueofthe"nu"propertyofanylocalepropertyof[[LocaleData]]mustnotincludethevalues"native","traditio",or"Linance".[[LocaleData]][locale]musthavehour12andhourNo0propertieswithBooleanvaluesforalllocalevalues.[[LocaleData]][locale]musthaveaformatspropertyforalllocalevalues.Thevalueofthispropertymustbeanarrayofobjects,eachofwhichhasasubsetofthepropertiesshowninTable4,whereeachpropertymusthaveoneofthevaluesspeciLiedforthepropertyinTable4.Multipleobjectsinanarraymayusethesamesubsetofthepropertiesaslongastheyhavedifferentvaluesfortheproperties.Thefollowingsubsetsmustbeavailableforeachlocale:

weekday,year,month,day,hour,minute,secondweekday,year,month,dayyear,month,dayyear,monthmonth,dayhour,minute,second

hour,minuteEachoftheobjectsmustalsohaveapatternproperty,whosevalueisaStringvaluethatcontainsforeachofthedateandtimeformatcomponentpropertiesoftheobjectasubstringstartingwith"{",followedbythenameoftheproperty,followedby"}".Iftheobjecthasanhourproperty,itmustalsohaveapattern12property,whosevalueisaStringvaluethat,inadditiontothesubstringsofthepatternproperty,containsasubstring"{ampm}".

EXAMPLEAnimplementationmightincludethefollowingobjectaspartofitsEnglishlocaledata:{hour:"numeric",minute:"2-digit",second:"2-digit",pattern:"{hour}:{minute}:{second}",pattern12:"{hour}:{minute}:{second}{ampm}"}.

NOTE2 ItisrecommendedthatimplementationsusethelocaledataprovidedbytheCommonLocaleDataRepository(availableathttp://cldr.unicode.org/).

TheIntl.DateTimeFormatprototypeobjectistheintrinsicobject%DateTimeFormatPrototype%.TheIntl.DateTimeFormatprototypeobjectisitselfan%DateTimeFormat%instance,whoseinternalslotsaresetasifithadbeenconstructedbytheexpressionConstruct(%DateTimeFormat%,«»,%Object%).

Inthefollowingdescriptionsoffunctionsthatarepropertiesor[[Get]]attributesofpropertiesoftheIntl.DateTimeFormatprototype

15 PropertiesoftheIntl.DateTimeFormatPrototypeObject




object,thephrase"thisDateTimeFormatobject"referstotheobjectthatisthethisvaluefortheinvocationofthefunction;aTypeErrorexceptionisthrownifthethisvalueisnotanobjectoranobjectthatdoesnothavean[[InitializedDateTimeFormat]]internalslotwithvaluetrue.

TheinitialvalueofIntl.DateTimeFormat.prototype.constructoristheintrinsicobject%DateTimeFormat%.



Intl.DateTimeFormat.prototype.formatisanaccessorpropertywhosesetaccessorfunctionisunde9ined.Itsgetaccessorfunctionperformsthefollowingsteps:

1. Letdtfbethisvalue.2. IfType(dtf)isnotObject,throwaTypeErrorexception.

15.1 Intl.DateTimeFormat.prototype.constructor

15.2 Intl.DateTimeFormat.prototype[@@toStringTag]

15.3 getIntl.DateTimeFormat.prototype.format


3. Letdtfbe?UnwrapDateTimeFormat(dtf).4. Ifdtf.[[BoundFormat]]isunde9ined,then

a. LetFbeanewbuilt-infunctionobjectasdeLinedinDateTimeFormatFunctions(12.1.5).

b. LetbfbeBoundFunctionCreate(F,dft,«»).c. Perform!DeLinePropertyOrThrow(bf,"length",PropertyDescriptor{[[Value]]:1,[[Writable]]:false,[[Enumerable]]:false,[[ConLigurable]]:true}).

d. Setdtf.[[BoundFormat]]tobf.5. Returndtf.[[BoundFormat]].

WhentheformatToPartsmethodiscalledwithanoptionalargumentdate,thefollowingstepsaretaken:

1. Letdtfbethisvalue.2. IfType(dtf)isnotObject,throwaTypeErrorexception.3. Ifdtfdoesnothavean[[InitializedDateTimeFormat]]internalslot,throwaTypeErrorexception.

4. Ifdateisnotprovidedorisunde9ined,thena. Letxbe%Date_now%().

5. Else,a. Letxbe?ToNumber(date).

6. Return?FormatDateTimeToParts(dtf,x).

Thisfunctionprovidesaccesstothelocaleandformattingoptions

15.4 Intl.DateTimeFormat.prototype.formatToParts([date])

15.5 Intl.DateTimeFormat.prototype.resolvedOptions()





computedduringinitializationoftheobject.ThisfunctioninitiallyinvokestheinternalalgorithmUnwrapDateTimeFormattogetthe%DateTimeFormat%objectonwhichtooperate.

ThefunctionreturnsanewobjectwhosepropertiesandattributesaresetasifconstructedbyanobjectliteralassigningtoeachofthefollowingpropertiesthevalueofthecorrespondinginternalslotofthisDateTimeFormatobject(see16):locale,calendar,numberingSystem,timeZone,hour12,weekday,era,year,month,day,hour,minute,second,andtimeZoneName.Propertieswhosecorrespondinginternalslotshavethevalueunde9inedarenotassigned.

NOTE InthisversionoftheECMAScript2017InternationalizationAPI,thetimeZonepropertywillbethenameofthedefaulttimezoneifnotimeZonepropertywasprovidedintheoptionsobjectprovidedtotheIntl.DateTimeFormatconstructor.TheLirsteditionleftthetimeZonepropertyunde9inedinthiscase.

Intl.DateTimeFormatinstancesinheritpropertiesfrom%DateTimeFormatPrototype%.

Intl.DateTimeFormatinstancesandotherobjectsthathavebeensuccessfullyinitializedasaDateTimeFormatobjecthave[[InitializedIntlObject]]and[[InitializedDateTimeFormat]]internalslotswhosevaluesaretrue.

16 PropertiesofIntl.DateTimeFormatInstances

ObjectsthathavebeensuccessfullyinitializedasaDateTimeFormatalsohaveseveralinternalslotsthatarecomputedbytheconstructor:

[[Locale]]isaStringvaluewiththelanguagetagofthelocalewhoselocalizationisusedforformatting.[[Calendar]]isaStringvaluewiththe"type"giveninUnicodeTechnicalStandard35forthecalendarusedforformatting.[[NumberingSystem]]isaStringvaluewiththe"type"giveninUnicodeTechnicalStandard35forthenumberingsystemusedforformatting.[[TimeZone]]isaStringvaluewiththeIANAtimezonenameofthetimezoneusedforformatting.[[Weekday]],[[Era]],[[Year]],[[Month]],[[Day]],[[Hour]],[[Minute]],[[Second]],[[TimeZoneName]]areeacheitherunde9ined,indicatingthatthecomponentisnotusedforformatting,oroneoftheStringvaluesgiveninTable4,indicatinghowthecomponentshouldbepresentedintheformattedoutput.[[Hour12]]isaBooleanvalueindicatingwhether12-hourformat(true)or24-hourformat(false)shouldbeused.Itisonlyusedwhen[[Hour]]isnotunde9ined.[[HourNo0]]isaBooleanvalueindicatingwhetherhoursfrom1to12(true)orfrom0to11(false)shouldbeused.Itisonlyusedwhen[[Hour12]]hasthevaluetrue.[[Pattern]]isaStringvalueasdescribedin14.3.

Finally,objectsthathavebeensuccessfullyinitializedasaDateTimeFormathavea[[BoundFormat]]internalslotthatcachesthefunctionreturnedbytheformataccessor(15.3).

17 LocaleSensitiveFunctionsoftheECMAScriptLanguage

TheECMAScriptLanguageSpeciLication,edition6orsuccessor,describesseverallocalesensitivefunctions.AnECMAScriptimplementationthatimplementsthisInternationalizationAPISpeciLicationshallimplementthesefunctionsasdescribedhere.

NOTE TheCollator,NumberFormat,orDateTimeFormatobjectscreatedinthealgorithmsinthisclauseareonlyusedwithinthesealgorithms.TheyareneverdirectlyaccessedbyECMAScriptcodeandneednotactuallyexistwithinanimplementation.

ThisdeLinitionsupersedesthedeLinitionprovidedinES2017,21.1.3.10.

WhenthelocaleComparemethodiscalledwithargumentthatandoptionalargumentslocales,andoptions,thefollowingstepsaretaken:

1. LetObeRequireObjectCoercible(thisvalue).2. LetSbe?ToString(O).3. LetthatValuebe?ToString(that).4. Letcollatorbe?Construct(%Collator%,«locales,options»).5. ReturnCompareStrings(collator,S,thatValue).

ThevalueofthelengthpropertyofthelocaleComparemethodis

Speci9ication

17.1 PropertiesoftheStringPrototypeObject

17.1.1 String.prototype.localeCompare(that[,locales[,options]])

https://tc39.github.io/ecma262/#sec-string.prototype.localecompare

https://tc39.github.io/ecma262/#sec-requireobjectcoercible




1.

NOTE1 ThelocaleComparemethoditselfisnotdirectlysuitableasanargumenttoArray.prototype.sortbecausethelatterrequiresafunctionoftwoarguments.

NOTE2 ThelocaleComparefunctionisintentionallygeneric;itdoesnotrequirethatitsthisvaluebeaStringobject.Therefore,itcanbetransferredtootherkindsofobjectsforuseasamethod.


Thisfunctioninterpretsastringvalueasasequenceofcodepoints,asdescribedinES2017,6.1.4.Thefollowingstepsaretaken:

1. LetObeRequireObjectCoercible(thisvalue).2. LetSbe?ToString(O).3. LetrequestedLocalesbe?CanonicalizeLocaleList(locales).4. LetlenbethenumberofelementsinrequestedLocales.5. Iflen>0,then

a. LetrequestedLocalebetheLirstelementofrequestedLocales.

6. Else,a. LetrequestedLocalebeDefaultLocale().

7. LetnoExtensionsLocalebetheStringvaluethatisrequestedLocalewithallUnicodelocaleextensionsequences(6.2.1)removed.

8. LetavailableLocalesbeaListwiththelanguagetagsofthe

17.1.2 String.prototype.toLocaleLowerCase([locales])

https://tc39.github.io/ecma262/#sec-string.prototype.tolocalelowercase

https://tc39.github.io/ecma262/#sec-ecmascript-language-types-string-type

https://tc39.github.io/ecma262/#sec-requireobjectcoercible



languagesforwhichtheUnicodecharacterdatabasecontainslanguagesensitivecasemappings.

9. LetlocalebeBestAvailableLocale(availableLocales,noExtensionsLocale).

10. Iflocaleisunde9ined,letlocalebe"und".11. LetcpListbeaListcontaininginorderthecodepointsofSas

deLinedinES2017,6.1.4,startingattheLirstelementofS.12. ForeachcodepointcincpList,iftheUnicodeCharacter

Databaseprovidesalowercaseequivalentofcthatiseitherlanguageinsensitiveorforthelanguagelocale,replacecincpListwiththat/thoseequivalentcodepoint(s).

13. LetcuListbeanewemptyList.14. ForeachcodepointcincpList,inorder,appendtocuListthe

elementsoftheUTF-16Encoding(deLinedinES2017,6.1.4)ofc.

15. LetLbeaStringwhoseelementsare,inorder,theelementsofcuList.

16. ReturnL.

TheresultmustbederivedaccordingtothecasemappingsintheUnicodecharacterdatabase(thisexplicitlyincludesnotonlytheUnicodeData.txtLile,butalsotheSpecialCasings.txtLilethataccompaniesit).

NOTE1 AsofUnicode5.1,theavailableLocaleslistcontainstheelements"az","lt",and"tr".

NOTE2 Thecasemappingofsomecodepointsmayproducemultiplecodepoints.InthiscasetheresultStringmaynotbethesamelengthasthesourceString.BecausebothtoLocaleUpperCaseandtoLocaleLowerCasehavecontext-sensitivebehaviour,thefunctionsarenotsymmetrical.Inotherwords,s.toLocaleUpperCase().toLocaleLowerCase()isnot





necessarilyequaltos.toLocaleLowerCase().

NOTE3 ThetoLocaleLowerCasefunctionisintentionallygeneric;itdoesnotrequirethatitsthisvaluebeaStringobject.Therefore,itcanbetransferredtootherkindsofobjectsforuseasamethod.


Thisfunctioninterpretsastringvalueasasequenceofcodepoints,asdescribedinES2017,6.1.4.ThisfunctionbehavesinexactlythesamewayasString.prototype.toLocaleLowerCase,exceptthatcharactersaremappedtotheiruppercaseequivalentsasspeciLiedintheUnicodecharacterdatabase.

NOTE ThetoLocaleUpperCasefunctionisintentionallygeneric;itdoesnotrequirethatitsthisvaluebeaStringobject.Therefore,itcanbetransferredtootherkindsofobjectsforuseasamethod.

ThefollowingdeLinition(s)refertotheabstractoperationthisNumberValueasdeLinedinES2017,20.1.3.

17.1.3 String.prototype.toLocaleUpperCase([locales])

17.2 PropertiesoftheNumberPrototypeObject

17.2.1 Number.prototype.toLocaleString([locales[,options]])

https://tc39.github.io/ecma262/#sec-string.prototype.tolocaleuppercase


https://tc39.github.io/ecma262/#sec-properties-of-the-number-prototype-object


WhenthetoLocaleStringmethodiscalledwithoptionalargumentslocalesandoptions,thefollowingstepsaretaken:

1. Letxbe?thisNumberValue(thisvalue).2. LetnumberFormatbe?Construct(%NumberFormat%,«locales,options»).

3. ReturnFormatNumber(numberFormat,x).

ThefollowingdeLinition(s)refertotheabstractoperationthisTimeValueasdeLinedinES2017,20.3.4.



1. Letxbe?thisTimeValue(thisvalue).2. IfxisNaN,return"InvalidDate".3. Letoptionsbe?ToDateTimeOptions(options,"any","all").4. LetdateFormatbe?Construct(%DateTimeFormat%,«locales,options»).

5. ReturnFormatDateTime(dateFormat,x).

17.3 PropertiesoftheDatePrototypeObject

17.3.1 Date.prototype.toLocaleString([locales[,options]])

https://tc39.github.io/ecma262/#sec-number.prototype.tolocalestring


https://tc39.github.io/ecma262/#sec-properties-of-the-date-prototype-object


https://tc39.github.io/ecma262/#sec-date.prototype.tolocalestring




WhenthetoLocaleDateStringmethodiscalledwithoptionalargumentslocalesandoptions,thefollowingstepsaretaken:

1. Letxbe?thisTimeValue(thisvalue).2. IfxisNaN,return"InvalidDate".3. Letoptionsbe?ToDateTimeOptions(options,"date","date").4. LetdateFormatbe?Construct(%DateTimeFormat%,«locales,options»).

5. ReturnFormatDateTime(dateFormat,x).


WhenthetoLocaleTimeStringmethodiscalledwithoptionalargumentslocalesandoptions,thefollowingstepsaretaken:

1. Letxbe?thisTimeValue(thisvalue).2. IfxisNaN,return"InvalidDate".3. Letoptionsbe?ToDateTimeOptions(options,"time","time").4. LettimeFormatbe?Construct(%DateTimeFormat%,«locales,options»).

5. ReturnFormatDateTime(timeFormat,x).

17.3.2 Date.prototype.toLocaleDateString([locales[,options]])

17.3.3 Date.prototype.toLocaleTimeString([locales[,options]])

17.4 PropertiesoftheArrayPrototypeObject

https://tc39.github.io/ecma262/#sec-date.prototype.tolocaledatestring



https://tc39.github.io/ecma262/#sec-date.prototype.tolocaletimestring





1. LetAbe?ToObject(thisvalue).2. Letlenbe?ToLength(?Get(A,"length")).3. LetseparatorbetheStringvalueforthelist-separatorStringappropriateforthehostenvironment’scurrentlocale(thisisderivedinanimplementation-deLinedway).

4. Ifleniszero,returntheemptyString.5. LetUirstElementbe?Get(A,"0").6. IfUirstElementisunde9inedornull,then

a. LetRbetheemptyString.7. Else,

a. LetRbe?ToString(?Invoke(UirstElement,"toLocaleString",«locales,options»)).

8. Letkbe1.9. Repeat,whilek<len

a. LetSbeaStringvalueproducedbyconcatenatingRandseparator.

b. LetnextElementbe?Get(A,ToString(k)).c. IfnextElementisunde9inedornull,then

i. LetRbetheemptyString.d. Else,

i. LetRbe?ToString(?Invoke(nextElement,"toLocaleString",«locales,options»)).

e. LetRbeaStringvalueproducedbyconcatenatingSandR.f. Increasekby1.

10. ReturnR.

NOTE1 TheelementsofthearrayareconvertedtoStrings

17.4.1 Array.prototype.toLocaleString([locales[,options]])

https://tc39.github.io/ecma262/#sec-array.prototype.tolocalestring






https://tc39.github.io/ecma262/#sec-invoke




https://tc39.github.io/ecma262/#sec-invoke

NOTE1 TheelementsofthearrayareconvertedtoStringsusingtheirtoLocaleStringmethods,andtheseStringsarethenconcatenated,separatedbyoccurrencesofaseparatorStringthathasbeenderivedinanimplementationdeLinedlocale-speciLicway.TheresultofcallingthisfunctionisintendedtobeanalogoustotheresultoftoString,exceptthattheresultofthisfunctionisintendedtobelocale-speciLic.

NOTE2 ThetoLocaleStringfunctionisintentionallygeneric;itdoesnotrequirethatitsthisvaluebeanArrayobject.Thereforeitcanbetransferredtootherkindsofobjectsforuseasamethod.

ThefollowingaspectsoftheECMAScript2017InternationalizationAPISpeciLicationareimplementationdependent:

Inallfunctionality:Additionalvaluesforsomepropertiesofoptionsarguments(2)CanonicalizationofextensionsubtagsequencesbeyondtherulesofRFC5646(6.2.3)Thedefaultlocale(6.2.4)Thedefaulttimezone(6.4.3)Thesetofavailablelocalesforeachconstructor(9.1)TheBestFitMatcheralgorithm(9.2.4)TheBestFitSupportedLocalesalgorithm(9.2.8)

InCollator:SupportfortheUnicodeextensionskeyskn,kfandthe

A ImplementationDependentBehaviour

paralleloptionspropertiesnumeric,caseFirst(10.1.1)Thesetofsupported"co"keyvalues(collations)perlocalebeyondadefaultcollation(10.2.3)Thesetofsupported"kn"keyvalues(numericcollation)perlocale(10.2.3)Thesetofsupported"kf"keyvalues(caseorder)perlocale(10.2.3)Thedefaultsearchsensitivityperlocale(10.2.3)Thesortorderforeachsupportedlocaleandoptionscombination(10.3.4)

InNumberFormat:Thesetofsupported"nu"keyvalues(numberingsystems)perlocale(11.3.3)Thepatternsusedforformattingpositiveandnegativevaluesasdecimal,percent,orcurrencyvaluesperlocale(11.1.7)LocalizedrepresentationsofNaNandIn9inity(11.1.7)TheimplementationofnumberingsystemsnotlistedinTable3(11.1.7)Localizeddecimalandgroupingseparators(11.1.7)Localizeddigitgroupingschemata(11.1.7)Localizedcurrencysymbolsandnames(11.1.7)

InDateTimeFormat:TheBestFitFormatMatcheralgorithm(12.1.1)Thesetofsupported"ca"keyvalues(calendars)perlocale(14.3)Thesetofsupported"nu"keyvalues(numberingsystems)perlocale(14.3)Thedefaulthour12andhourNo0settingsperlocale(14.3)Thesetofsupporteddate-timeformatsperlocalebeyondacoreset,includingtherepresentationsusedforeachcomponentandtheassociatedpatterns(14.3)Localizedweekdaynames,eranames,monthnames,

am/pmindicators,andtimezonenames(12.1.7)Thecalendriccalculationsusedforcalendarsotherthan"gregory",andadjustmentsforlocaltimezonesanddaylightsavingtime(12.1.7)

10.1,11.2,13InECMA-402,1stEdition,constructorscouldbeusedtocreateIntlobjectsfromarbitraryobjects.Thisisnolongerpossiblein2ndEdition.15.3InECMA-402,1stEdition,thelengthpropertyofthefunctionobjectFwassetto0.In2ndEdition,lengthissetto1.

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ECMAScript Internationalization API Specification · Internationalization API Specification . ... 12.1.1 InitializeDateTimeFormat ... The 1st Edition API was developed by an ad-hoc