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Stage: 3

Champion:Younies Mahmoud,Ujjwal Sharma

Authors:Younies Mahmoud,Ujjwal Sharma

Stage 3 Reviewers

• Michael Ficarra@michaelficarra
• Ron Buckton@rbuckton
• Ross Kirsling@rkirsling

Resources

• Spec text inecmarkup output format
• Stage 2 slides
• Stage 3 slides

• This proposal reached Stage 1 at the 2020 Feb TC39 meeting.
• This proposal reached Stage 2 at the 2020 June TC39 meeting.
• This proposal reached Stage 3 at the 2021 October TC39 meeting.

• Time Duration is how long something lasts, from the start to end. It can be represented by a single time unit or multiple ones.
  • For example,
    • 10000 seconds
    • 2 hours 46 minutes 40 seconds
• Every locale has its own way to format duration.
  • For example:
    • en-US: 1 hour, 46 minutes and 40 seconds
    • fr-FR: 1 heure, 46 minutes et 40 secondes
• There are multiple widths for the time duration.
  • For example, wide and short
    • 1 hour, 46 minutes and 40 seconds → Wide
    • 1 hr, 46 min, 40 sec → Short

newIntl.DurationFormat("fr-FR",{style:"long"}).format({hours:1,minutes:46,seconds:40,});// => "1 heure, 46 minutes et 40 secondes"

• Users need all types of duration formatting depending on the requirements of their application. For example, to show how long a flight takes, the duration should be in Short or Narrow format
  • "1 hr 40 min 60 sec" → Short
  • "1h 40m 60s" → Narrow

In this section, we are going to illustrate each user needs (requirements) and a design for each need (requirement)

• Users need the following fields to be supported
  • Years
  • Months
  • Weeks
  • Days
  • Hours
  • Minutes
  • Seconds
  • Milliseconds
  • Microseconds
  • Nanoseconds

• Duration objects support the same fields as inTemporal.Duration, which contains:
  • years
  • months
  • weeks
  • days
  • hours
  • minutes
  • seconds
  • milliseconds
  • microseconds
  • nanoseconds

• Users need to identify how to input a duration value. For example, if a user needs to format1000 seconds , how could the user pass the value to the formatting function.

• Input value will be a duration object, containing fields for some number of the supported duration units fields.
• Example:new DurationFormat().format({hours: 3, minutes: 4});

Users want to determine several types of the formatting width as following

• The user can determine the formatting width using a parameterstyle and the value of this parameter may be one of the following strings:
  • "long"
  • "short"
  • "narrow"
  • "digital"
• The width of each field can be set separately in the options, for example:{ years: "long", months: "short", days: "narrow" }.

DurationFormat does not do any arithmetic operations nor rounding on the input implicitly.Instead, the user must edit the input to ensure the input is within the desired range.

To avoid accidentally omitting part of the duration,DurationFormat always outputs all nonzero fields (except sub-second fields truncated byfractionalDigits).Callers who want to omit nonzero fields (for example, only showing the date or time portion of the duration) should edit the input duration.

• Durations are stored in duration objects containing the fields above.
• Example:

constduration={hours:1,minutes:2,seconds:33};

In most cases, users want to avoid displaying zero-value fields. All zero-valued fields are hidden by default. If you specify the style for a specific field, then it is always displayed, but you can override that behavior by also setting the display option for that particular field to"auto" again explicitly.

For each fieldfoo, there is an optionfooDisplay that is set to"auto" by default. Setting that option to"always" causes that field to be displayed even if it is zero; for example, to always show the "day" field, set{ dayDisplay: "always" }. If you specify the style for that field by setting thefoo option, then the default forfooDisplay becomes"always"; for example,{ day: "short" } implies{ day: "short", dayDisplay: "always" }.

• Users needs the formatting to be dependent on the locale
• For example:
  • en-US
    • 1 hour, 46 minutes and 40 seconds
  • fr-FR
    • 1 heure, 46 minutes et 40 secondes

Adding the locale in string format as a first argument, or specifying a ranked list of locales as an array of string values.

Sometimes it is desirable to display the smallest sub-second unit not by itself but as a fraction of the immediately larger unit.

We allow users to specify afractionalDigits option that will display the smallest sub-second unit with display set to"auto" as a fraction of the previous unit if it is non-zero and if these values have style set to"numeric". The number of digits used will be the value passed to this option. By defaultfractionalDigits is undefined. In this case, exactly as many fractional digits as needed to display the whole duration are included. If rounding is necessary, we round toward 0.

constduration={seconds:12,milliseconds:345,microseconds:600};newIntl.DurationFormat('en',{style:"digital",fractionalDigits:2}).format(duration);// "0:00:12.35"newIntl.DurationFormat('en',{seconds:"numeric",fractionalDigits:2}).format(duration);// "12.35">newIntl.DurationFormat('en',{seconds:"numeric",fractionalDigits:5}).format(duration);// "12.34560">newIntl.DurationFormat('en',{seconds:"numeric"}).format(duration);// "12.3456"

newIntl.DurationFormat(locales,options)

• locales: Array<string> | string: A locale string or a list of locale strings in decreasing order of preference.
• options?: object: An object for configuring the behavior of the instance. It may have some or all of the following properties:
  • localeMatcher: "best fit" | "lookup": A string denoting which locale matching algorithm to use. Defaults to"best fit".
  • numberingSystem: string: A string containing the name of the numbering system to be used for number formatting.
  • style: "long" | "short" | "narrow" | "digital": The base style to be used for formatting. This can be overriden per-unit by setting the more granular options. Defaults to"short".
  • years: "long" | "short" | "narrow": The style to be used for formatting years.
  • yearsDisplay: "always" | "auto": Whether to always display years, or only if nonzero.
  • months: "long" | "short" | "narrow": The style to be used for formatting months.
  • monthsDisplay: "always" | "auto": Whether to always display months, or only if nonzero.
  • weeks: "long" | "short" | "narrow": The style to be used for formatting weeks.
  • weeksDisplay: "always" | "auto": Whether to always display weeks, or only if nonzero.
  • days: "long" | "short" | "narrow": The style to be used for formatting days.
  • daysDisplay: "always" | "auto": Whether to always display days, or only if nonzero.
  • hours: "long" | "short" | "narrow" | "numeric" | "2-digit": The style to be used for formatting hours.
  • hoursDisplay: "always" | "auto": Whether to always display hours, or only if nonzero.
  • minutes: "long" | "short" | "narrow" | "numeric" | "2-digit": The style to be used for formatting minutes.
  • minutesDisplay: "always" | "auto": Whether to always display minutes, or only if nonzero.
  • seconds: "long" | "short" | "narrow" | "numeric" | "2-digit": The style to be used for formatting seconds.
  • secondsDisplay: "always" | "auto": Whether to always display seconds, or only if nonzero.
  • milliseconds: "long" | "short" | "narrow" | "numeric": The style to be used for formatting milliseconds.
  • millisecondsDisplay: "always" | "auto": Whether to always display milliseconds, or only if nonzero.
  • microseconds: "long" | "short" | "narrow" | "numeric": The style to be used for formatting microseconds.
  • microsecondsDisplay: "always" | "auto": Whether to always display microseconds, or only if nonzero.
  • nanoseconds: "long" | "short" | "narrow" | "numeric": The style to be used for formatting nanoseconds.
  • nanosecondsDisplay: "always" | "auto": Whether to always display nanoseconds, or only if nonzero.
  • fractionalDigits: number: How many fractional digits to display in the output.Additional decimal places will be truncated towards zero.(Temporal.Duration.prototype.round can be used to obtain different rounding behavior.)Normally this option applies to fractional seconds, but this option actually applies to the largest seconds-or-smaller unit that uses the"numeric" or"2-digit" style.For example, if options are{ seconds: "narrow", milliseconds: "numeric", fractionalDigits: 4} then the output is "12.3456 seconds".If this option is omitted, only nonzero decimals will be displayed and trailing zeroes will be omitted.

• The per-unit style options default to the value ofstyle for all styles except"digital", for which units years till days default to"short" and hours till nanoseconds default to"numeric".
• Ifstyle isundefined, all values default to"short"
• The per-unit display options default to"auto" if the corresponding style option isundefined and"always" otherwise.

• Some locales may share the same representation between"long" and"short" or between"narrow" and"short". Others may use different representations for each one, e.g. "3 seconds", "3 secs", "3s".
• Any unit with the style"numeric" preceded by a unit of style"numeric" or"2-digit" should act like the style"2-digit" was used instead. For example,{hours: 'numeric', minutes: 'numeric'} can produce output like "3:08".

newIntl.DurationFormat('en').format(duration)

• duration (Temporal.Duration |string |object): The duration to be formatted. This could either be aTemporal.Duration object or a string or options bag that can be converted into one.

Astring containing the formatted duration.

newIntl.DurationFormat('en').formatToParts(duration)

• duration (Temporal.Duration |string |object): The duration to be formatted. This could either be aTemporal.Duration object or a string or options bag that can be converted into one.

AnArray<{type: string, value: string}> containing the formatted duration in parts.

Three v8 prototypes (try to use two different possible ICU classes) were made, ALL are:

• Sync with"Stage 1 Draft / June 1, 2020" version of spec
• Flag --harmony_intl_duration_format
• Have not implement any changes not yet spec out inhttps://tc39.es/proposal-intl-duration-format/ such as
  • hideZeroValued
  • smallestUnit / largestUnit

1. Base the implementation onicu::MeasureFormat::formatMeasures()
   • https://chromium-review.googlesource.com/c/v8/v8/+/2762664
   • Not yet implment formatToParts
   • Need solution ofICU-21543 "Add methods to return FormattedValue to MeasureFormat " to implement formatToParts().
2. Based onthe support of "-and-" unit in LocalizedNumberFormatter
   • https://chromium-review.googlesource.com/c/v8/v8/+/2775300
   • Not yet implment formatToParts
   • Not yet implement style:"digital"
   • Need solution of the following to implement formatToParts():
     • ICU-21544 "unit format in number formatter return U_INTERNAL_PROGRAM_ERROR with "year-and-" (except month) and "month-and-""
     • ICU-21547 "nextPosition() of FormattedNumber of unit with "-and-" is buggy"
3. Based on icu::ListFormatter and icu::number::LocalizedNumberFormatter w/o depend on the "X-and-Y" units.
   • https://chromium-review.googlesource.com/c/v8/v8/+/2776518
   • Implements formatToParts
   • Not yet implement style:"digital"