Stage 3 Draft / October 7, 2021

Intl Enumeration API Specification

Introduction

This proposal adds several function properties to the Intl Object to list supported values of options. See the README for more context.

1 Identification of Locales, Currencies, Time Zones, and Measurement Units, Numbering Systems, Collations, and Calendars

This clause describes the String values used in the ECMAScript 2022 Internationalization API Specification to identify locales, currencies, time zones, and measurement units, numbering systems, collations, and calendars .

1.1 Case Sensitivity and Case Mapping

The String values used to identify locales, currencies, and time zones are interpreted in a case-insensitive manner, treating the Unicode Basic Latin characters "A" to "Z" (U+0041 to U+005A) as equivalent to the corresponding Basic Latin characters "a" to "z" (U+0061 to U+007A). No other case folding equivalences are applied. When mapping to upper case, a mapping shall be used that maps characters in the range "a" to "z" (U+0061 to U+007A) to the corresponding characters in the range "A" to "Z" (U+0041 to U+005A) and maps no other characters to the latter range.

EXAMPLES "ß" (U+00DF) must not match or be mapped to "SS" (U+0053, U+0053). "ı" (U+0131) must not match or be mapped to "I" (U+0049).

1.2 Language Tags

...

1.3 Currency Codes

The ECMAScript 2022 Internationalization API Specification identifies currencies using 3-letter currency codes as defined by ISO 4217. Their canonical form is upper case.

All well-formed 3-letter ISO 4217 currency codes are allowed. However, the set of combinations of currency code and language tag for which localized currency symbols are available is implementation dependent. Where a localized currency symbol is not available, the ISO 4217 currency code is used for formatting.

1.3.1 IsWellFormedCurrencyCode ( currency )

The IsWellFormedCurrencyCode abstract operation verifies that the currency argument (which must be a String value) represents a well-formed 3-letter ISO currency code. The following steps are taken:

  1. Let normalized be the result of mapping currency to upper case as described in 1.1.
  2. If the number of elements in normalized is not 3, return false.
  3. If normalized contains any character that is not in the range "A" to "Z" (U+0041 to U+005A), return false.
  4. Return true.

1.3.2 AvailableCurrencies ( )

The AvailableCurrencies abstract operation returns a List, ordered as if an Array of the same values had been sorted using %Array.prototype.sort% using undefined as comparefn, that contains unique, well-formed, and upper case canonicalized 3-letter ISO 4217 currency codes, identifying the currencies for which the implementation provides the functionality of Intl.DisplayNames and Intl.NumberFormat objects.

1.4 Time Zone Names

The ECMAScript 2022 Internationalization API Specification identifies time zones using the Zone and Link names of the IANA Time Zone Database. Their canonical form is the corresponding Zone name in the casing used in the IANA Time Zone Database.

All registered Zone and Link names are allowed. Implementations must recognize all such names, and use best available current and historical information about their offsets from UTC and their daylight saving time rules in calculations. However, the set of combinations of time zone name and language tag for which localized time zone names are available is implementation dependent.

1.4.1 IsValidTimeZoneName ( timeZone )

The IsValidTimeZoneName abstract operation verifies that the timeZone argument (which must be a String value) represents a valid Zone or Link name of the IANA Time Zone Database.

The abstract operation returns true if timeZone, converted to upper case as described in 1.1, is equal to one of the Zone or Link names of the IANA Time Zone Database, converted to upper case as described in 1.1. It returns false otherwise.

1.4.2 CanonicalizeTimeZoneName

The CanonicalizeTimeZoneName abstract operation returns the canonical and case-regularized form of the timeZone argument (which must be a String value that is a valid time zone name as verified by the IsValidTimeZoneName abstract operation). The following steps are taken:

  1. Let ianaTimeZone be the Zone or Link name of the IANA Time Zone Database such that timeZone, converted to upper case as described in 1.1, is equal to ianaTimeZone, converted to upper case as described in 1.1.
  2. If ianaTimeZone is a Link name, let ianaTimeZone be the corresponding Zone name as specified in the "backward" file of the IANA Time Zone Database.
  3. If ianaTimeZone is "Etc/UTC" or "Etc/GMT", return "UTC".
  4. Return ianaTimeZone.

The Intl.DateTimeFormat constructor allows this time zone name; if the time zone is not specified, the host environment's current time zone is used. Implementations shall support UTC and the host environment's current time zone (if different from UTC) in formatting.

1.4.3 DefaultTimeZone ()

The DefaultTimeZone abstract operation returns a String value representing the valid (1.4.1) and canonicalized (1.4.2) time zone name for the host environment's current time zone.

1.4.4 AvailableTimeZones ()

The AvailableTimeZones abstract operation returns a sorted List of supported Zone and Link names in the IANA Time Zone Database. The following steps are taken:

  1. Let names be a List of all supported Zone and Link names in the IANA Time Zone Database.
  2. Let result be a new empty List.
  3. For each element name of names, do
    1. Assert: ! IsValidTimeZoneName( name ) is true.
    2. Let canonical be ! CanonicalizeTimeZoneName( name ).
    3. If result does not contain an element equal to canonical, then
      1. Append canonical to the end of result.
  4. Sort result in order as if an Array of the same values had been sorted using %Array.prototype.sort% using undefined as comparefn.
  5. Return result.

1.5 Measurement Unit Identifiers

The ECMAScript 2022 Internationalization API Specification identifies measurement units using a core unit identifier as defined by Unicode Technical Standard #35, Part 2, Section 6. Their canonical form is a string containing all lowercase letters with zero or more hyphens.

Only a limited set of core unit identifiers are allowed. An illegal core unit identifier results in a RangeError.

1.5.1 IsWellFormedUnitIdentifier ( unitIdentifier )

The IsWellFormedUnitIdentifier abstract operation verifies that the unitIdentifier argument (which must be a String value) represents a well-formed core unit identifier as defined in UTS #35, Part 2, Section 6. In addition to obeying the UTS #35 core unit identifier syntax, unitIdentifier must be one of the identifiers sanctioned by UTS #35 or be a compound unit composed of two sanctioned simple units. The following steps are taken:

  1. If the result of IsSanctionedSimpleUnitIdentifier(unitIdentifier) is true, then
    1. Return true.
  2. If the substring "-per-" does not occur exactly once in unitIdentifier, then
    1. Return false.
  3. Let numerator be the substring of unitIdentifier from the beginning to just before "-per-".
  4. If the result of IsSanctionedSimpleUnitIdentifier(numerator) is false, then
    1. Return false.
  5. Let denominator be the substring of unitIdentifier from just after "-per-" to the end.
  6. If the result of IsSanctionedSimpleUnitIdentifier(denominator) is false, then
    1. Return false.
  7. Return true.

1.5.2 IsSanctionedSimpleUnitIdentifier ( unitIdentifier )

The IsSanctionedSimpleUnitIdentifier abstract operation verifies that the given core unit identifier is among the simple units sanctioned in the current version of the ECMAScript Internationalization API Specification, a subset of the Validity Data as described in UTS #35, Part 1, Section 3.11; the list may grow over time. As discussed in UTS #35, a simple unit is one that does not have a numerator and denominator. The following steps are taken:

  1. If unitIdentifier is listed in Table 1 below, return true.
  2. Else, Return false.
Table 1: Simple units sanctioned for use in ECMAScript
Simple Unit
acre
bit
byte
celsius
centimeter
day
degree
fahrenheit
fluid-ounce
foot
gallon
gigabit
gigabyte
gram
hectare
hour
inch
kilobit
kilobyte
kilogram
kilometer
liter
megabit
megabyte
meter
mile
mile-scandinavian
milliliter
millimeter
millisecond
minute
month
ounce
percent
petabyte
pound
second
stone
terabit
terabyte
week
yard
year

1.5.3 AvailableUnits ( )

The AvailableUnits abstract operation returns a List, ordered as if an Array of the same values had been sorted using %Array.prototype.sort% using undefined as comparefn, that contains the unique values of simple unit identifiers listed in every row of Table 1, except the header row.

1.6 Numbering System Identifiers

The ECMAScript 2022 Internationalization API Specification identifies numbering systems using a numbering system identifier as defined by Unicode Technical Standard #35, Part 3, Section 1. Their canonical form is a string containing all lowercase letters.

1.6.1 AvailableNumberingSystems ( )

The AvailableNumberingSystems abstract operation returns a List, ordered as if an Array of the same values had been sorted using %Array.prototype.sort% using undefined as comparefn, that contains unique numbering systems identifiers identifying the numbering systems for which the implementation provides the functionality of Intl.DateTimeFormat, Intl.NumberFormat, and Intl.RelativeTimeFormat objects. The list must include the Numbering System value of every row of Table 4, except the header row.

1.7 Collation Types

The ECMAScript 2022 Internationalization API Specification identifies collations using a collation type as defined by Unicode Technical Standard #35, Part 5, Section 3.1. Their canonical form is a string containing all lowercase letters with zero or more hyphens.

1.7.1 AvailableCollations ( )

The AvailableCollations abstract operation returns a List, ordered as if an Array of the same values had been sorted using %Array.prototype.sort% using undefined as comparefn, that contains unique collation types identifying the collations for which the implementation provides the functionality of Intl.Collator objects.

1.8 Calendar Types

The ECMAScript 2022 Internationalization API Specification identifies calendars using a calendar type as defined by Unicode Technical Standard #35, Part 4, Section 2. Their canonical form is a string containing all lower case letters with zero or more hyphens.

1.8.1 AvailableCalendars ( )

The AvailableCalendars abstract operation returns a List, ordered as if an Array of the same values had been sorted using %Array.prototype.sort% using undefined as comparefn, that contains unique calendar types identifying the calendars for which the implementation provides the functionality of Intl.DateTimeFormat objects. The list must include "gregory".

2 The Intl Object

The Intl object is the %Intl% intrinsic object and the initial value of the "Intl" property of the global object. The Intl object is a single ordinary object.

The value of the [[Prototype]] internal slot of the Intl object is the intrinsic object %ObjectPrototype%.

The Intl object is not a function object. It does not have a [[Construct]] internal method; it is not possible to use the Intl object as a constructor with the new operator. The Intl object does not have a [[Call]] internal method; it is not possible to invoke the Intl object as a function.

The Intl object has an internal slot, [[FallbackSymbol]], which is a new %Symbol% in the current realm with the [[Description]] "IntlLegacyConstructedSymbol".

2.1 Constructor Properties of the Intl Object

2.1.1 Intl.Locale (...)

See 10.

2.1.2 Intl.Collator (...)

See 11.

2.1.3 Intl.NumberFormat (...)

See 12.

2.1.4 Intl.DateTimeFormat (...)

See 13.

2.1.5 Intl.RelativeTimeFormat (...)

See 14.

2.1.6 Intl.PluralRules (...)

See 15.

Note
In ECMA 402 v1, Intl constructors supported a mode of operation where calling them with an existing object as a receiver would transform the receiver into the relevant Intl instance with all internal slots. In ECMA 402 v2, this capability was removed, to avoid adding internal slots on existing objects. In ECMA 402 v3, the capability was re-added as "normative optional" in a mode which chains the underlying Intl instance on any object, when the constructor is called. See Issue 57 for details.

2.2 Function Properties of the Intl Object

2.2.1 Intl.getCanonicalLocales ( locales )

When the getCanonicalLocales method is called with argument locales, the following steps are taken:

  1. Let ll be ? CanonicalizeLocaleList(locales).
  2. Return CreateArrayFromList(ll).

2.2.2 Intl.supportedValuesOf ( key )

When the supportedValuesOf method is called with argument key , the following steps are taken:

  1. Let key be ? ToString(key).
  2. If key is "calendar", then
    1. Let list be ! AvailableCalendars( ).
  3. Else if key is "collation", then
    1. Let list be ! AvailableCollations( ).
  4. Else if key is "currency", then
    1. Let list be ! AvailableCurrencies( ).
  5. Else if key is "numberingSystem", then
    1. Let list be ! AvailableNumberingSystems( ).
  6. Else if key is "timeZone", then
    1. Let list be ! AvailableTimeZones( ).
  7. Else if key is "unit", then
    1. Let list be ! AvailableUnits( ).
  8. Else,
    1. Throw a RangeError exception.
  9. Return ! CreateArrayFromList( list ).

A Copyright & Software License

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