# `Intl.DurationFormat` update ### Ben Allen, 100th TC39 --- # Major refactor * Current version of proposal has one AO, `PartitionDurationFormatPattern`, that has hard-to-read / hard-to-implement complexities * Most of these complexities are related to the need for special handling when formatting units with `"numeric"` and `"2-digit"` styles * The complexity of this AO has proved *quite annoying* for implementors --- # Major refactor * Refactor splits out handling for these styles into new AOs * Additional refactor in progress: simplify`FormatNumericUnits` AO --- # Why are `"numeric"`-like styles difficult? * All other duration unit styles produce separated lists (in `'en'` these lists separated by commas and/or "and") * `"numeric"`-like styles produce output resembling the display on a digital clock, with hour/minute and minute/second separators between them --- * `df = new Intl.DurationFormat('en', {style: "short"}).format({hours: 1, minutes: 2, seconds: 3}) --> "1 hr, 2 min, 3 sec"` * `df = new Intl.DurationFormat('en', {hours: "numeric"}).format({hours: 1, minutes: 2, seconds: 3}) --> "1:02:03"` --- # Why are `"numeric"`-like styles difficult? * `"numeric"`-like formatting is a fundamentally different task than formatting the other styles, and the steps for handling it are likewise different * Previously the steps for `"numeric"`-like and non-`"numeric"`-like had been intermixed, producing most of the frustrating complexity --- # Other editorial (?) changes * Alongside the refactor are potentially normative changes related to `"numeric"`-like formatting. * Several new slots for locale-dependent information introduced, (largely) in preparation for a hypothetical DurationFormat.v2 --- # Other editorial (?) changes * `[[HoursMinutesSeparator]]` and `[[MinutesSecondsSeparator]]` * Some locales use different separators between hours/minutes and minutes/seconds. * For example, `fr-CA` uses 'h' between hours and minutes, and 'm' between minutes and seconds --- # Other editorial (?) changes * `[HoursDigits]]` * Some locales, notably 'af', use two-digit hours for clock-style formatting, i.e. "07:00" instead of "7:00". This slot allows us to produce properly-formatted output for those locales --- # Other editorial (?) changes * To ensure that this update is purely editorial, the current version has a note saying that `[[HoursMinutesSeparator]]` and `[[MinutesSecondsSeparator]]` must be the same, and a note saying that `[[HoursDigits]]` must be 1 --- # Reasoning * Need to avoid major normative changes while at Stage 3 * However: Because both of these changes are about correctly formatting durations for all locales, this could be conceptualized as a bugfix --- # Thanks!