Temporal & Intl

Temporal

Standard Temporal date/time API. Prefer it over error-prone Date for calendar dates, wall-clock time, precise instants, and time zones.

Available Types

Type	Description
Temporal.Now	Current instant / current time zone
Temporal.Instant	Precise instant (UTC epoch nanoseconds)
Temporal.ZonedDateTime	Date-time with time zone
Temporal.PlainDate	Calendar date (no time, no zone)
Temporal.PlainTime	Wall-clock time
Temporal.PlainDateTime	Date + time (no zone)
Temporal.PlainYearMonth	Year-month
Temporal.PlainMonthDay	Month-day
Temporal.Duration	Duration

Also available:

• Date.prototype.toTemporalInstant() — convert legacy Date to Temporal.Instant

Examples

// Parse calendar date
const d = Temporal.PlainDate.from("2024-03-15");
const nextWeek = d.add({ days: 7 }); // 2024-03-22

// Now in a time zone
const zdt = Temporal.Now.zonedDateTimeISO("Asia/Shanghai");
console.log(zdt.toString());
// e.g. 2026-07-15T20:30:00+08:00[Asia/Shanghai]

// Instant arithmetic
const instant = Temporal.Instant.from("2024-03-15T12:00:00Z");
const later = instant.add({ hours: 2 });

// Duration
const span = Temporal.Duration.from({ days: 2, hours: 3 });
console.log(span.toString()); // "P2DT3H"

// Convert from Date
const fromDate = new Date("2024-03-15T00:00:00Z").toTemporalInstant();

Type Support

After installing breeze-plugin-kit, global Temporal and Date.prototype.toTemporalInstant types are injected automatically — no extra import:

// Use global Temporal with full IDE completion
const date: Temporal.PlainDate = Temporal.PlainDate.from("2024-01-01");
const now: Temporal.ZonedDateTime = Temporal.Now.zonedDateTimeISO();

Type source: breeze-plugin-kit src/types/temporal.d.ts (based on temporal-spec).

Notes

• Injected via temporal-polyfill, aligned with the ECMAScript Temporal spec
• Named zones (e.g. America/New_York, Asia/Shanghai) and offset zones (e.g. +08:00) work
• Depends on the host time-focused Intl (DateTimeFormat); non-Gregorian calendars are not guaranteed — prefer iso8601 / gregory
• Do not use Date for cross-zone add/subtract; prefer PlainDate / ZonedDateTime for calendar semantics

Intl

QuickJS has no built-in ECMA-402. Breeze ships a time-focused Intl subset for locale-aware date/time formatting and Temporal time-zone support.

Implemented

API	Notes
Intl.DateTimeFormat	Locale date/time formatting (format / formatToParts / resolvedOptions)
Intl.DateTimeFormat.supportedLocalesOf	Minimal implementation
Intl.supportedValuesOf("timeZone")	IANA zones (links canonicalize to primary)
Intl.supportedValuesOf("calendar")	Calendar id list
Intl.getCanonicalLocales	Minimal implementation
Date.prototype.toLocaleString	Wired to Intl.DateTimeFormat
Date.prototype.toLocaleDateString	Same (default date fields)
Date.prototype.toLocaleTimeString	Same (default time fields)

Examples

const epoch = Date.UTC(2024, 8, 10, 15, 37, 20);

// Locale conventions
new Intl.DateTimeFormat("zh-CN", {
  dateStyle: "long",
  timeZone: "Asia/Shanghai",
}).format(epoch);

new Intl.DateTimeFormat("en-GB", {
  dateStyle: "short",
  timeZone: "UTC",
}).format(epoch);

// Lone option
new Intl.DateTimeFormat("en", {
  year: "numeric",
  timeZone: "UTC",
}).format(epoch); // "2024"

// Fixed offset zones
new Intl.DateTimeFormat("en", {
  timeZone: "+00:00",
  year: "numeric",
}).resolvedOptions().timeZone; // "UTC"

// Common aliases are canonicalized
new Intl.DateTimeFormat("en", {
  timeZone: "Asia/Calcutta",
}).resolvedOptions().timeZone; // "Asia/Kolkata"

Type Support

After installing breeze-plugin-kit, time-focused Intl and Temporal types are injected automatically:

const fmt = new Intl.DateTimeFormat("zh-CN", {
  dateStyle: "long",
  timeZone: "Asia/Shanghai",
});
const text: string = fmt.format(Date.now());

// Only timeZone / calendar are guaranteed at runtime
const zones: string[] = Intl.supportedValuesOf("timeZone");

Type sources:

• breeze-plugin-kit src/types/intl.d.ts (Breeze time-focused constraints)
• src/types/temporal.d.ts (Temporal + DateTimeFormat overloads for Temporal objects)

Notes

• Time zones: jiff for IANA / offset math; common links (e.g. Etc/GMT → UTC) are canonicalized
• Locale formatting: ICU4X (en-US / zh-CN / ja-JP conventions differ)
• Option conflicts: dateStyle / timeStyle together with field options or timeZoneName throw TypeError
• hourCycle: "h24": midnight hour displays as 24
• Not supported: Collator (sorting), NumberFormat / currency, and other non-time Intl
• Enough for “show times in local conventions / convert zones”; do not rely on collation or currency formatting