areDateTimesEqualBy

Signature

areDateTimesEqualBy(value1: string, value2: string, unit: any, optionsArg?: { weekStartsOn?: "monday" | "sunday"; fractionalSecondDigits?: FractionalDigit; }): boolean

import { areDateTimesEqualBy } from "@northguild/gmt/plain/compare";

Compare two ISO datetime strings for equality at a given unit.

• Equality means both values share the same start-of-unit boundary, so "month" requires the same month AND year — March 2023 and March 2024 are NOT equal by month, matching date-fns’s isSameMonth and Luxon’s dt.hasSame(other, "month").
• Supports the full Temporal.DateUnit \| Temporal.TimeUnit range, down to "nanosecond".
• Returns false for an unsupported unit or invalid input. Mapping from date-fns (Decision 5, context/roadmap/issues/J.md):
• isSameDay(a, b) → areDateTimesEqualBy(a, b, "day")
• isSameHour(a, b) → areDateTimesEqualBy(a, b, "hour")
• isSameMinute(a, b) → areDateTimesEqualBy(a, b, "minute")
• isSameSecond(a, b) → areDateTimesEqualBy(a, b, "second")
• isSameMonth(a, b) → areDateTimesEqualBy(a, b, "month")
• isSameYear(a, b) → areDateTimesEqualBy(a, b, "year")

Parameters

Parameter	Type	Description
value1	string	first ISO datetime string
value2	string	second ISO datetime string
unit	any	Temporal.DateUnit | Temporal.TimeUnit to compare by

Options

options

Option	Type	Default
weekStartsOn?	"monday" | "sunday"	—
fractionalSecondDigits?	FractionalDigit	—

Returns

true if both datetimes share the same start-of-unit boundary, false on an unsupported unit or invalid input

Related types

• FractionalDigit

Examples

areDateTimesEqualBy("2024-03-15T10:00:00", "2024-03-15T18:00:00", "day") // true
areDateTimesEqualBy("2024-03-15T10:30:00", "2024-03-15T10:45:00", "hour") // true
areDateTimesEqualBy("2024-03-15T10:30:00", "2024-03-15T11:00:00", "hour") // false
areDateTimesEqualBy("2023-03-15T10:00:00", "2024-03-15T10:00:00", "month") // false (same month, different year)
areDateTimesEqualBy("invalid", "2024-03-15T10:00:00", "day") // false

Source

plain/compare/areDateTimesEqualBy.ts