eachMonth

Returns an array of Date objects for the first day of each month from start to end (inclusive).

Each returned Date is normalized to the 1st of the month at 00:00:00.000. If start > end, an empty array is returned. Returns an empty array if either input is invalid.

Available since v2.0.0

Import

import { eachMonth } from '@helpers4/date';

Signature

eachMonth(start: DateLike, end: DateLike): Date[]

Parameters

Parameter	Type	Description
start	DateLike	Start date (inclusive — the month containing this date is included)
end	DateLike	End date (inclusive — the month containing this date is included)

Returns

Date[] — An array of Date objects, one per month (each on the 1st)

Examples

eachMonth

eachMonth('2025-01-15', '2025-04-10')
// => [Date(2025-01-01), Date(2025-02-01), Date(2025-03-01), Date(2025-04-01)]

Related Types

DateLike

A value that can be converted to a Date.

• Date — used as-is (validated for Invalid Date)
• number — treated as a timestamp (seconds or milliseconds, auto-detected); 0 is treated as invalid and produces null in ensureDate
• string — parsed via new Date(string)
• EpochMilliseconds — any object with a epochMilliseconds property (e.g. Temporal.Instant, Temporal.ZonedDateTime)

// TODO: When the Temporal API reaches Stage 4 and is available without // flags in all major runtimes, consider narrowing the union to the // concrete Temporal types for stricter type-checking.

type DateLike = Date | number | string | EpochMilliseconds

EpochMilliseconds

An object that exposes an epoch timestamp in milliseconds.

This structural type is satisfied by Temporal.Instant and Temporal.ZonedDateTime (and any future object that carries the same property), so callers can pass Temporal values without importing them.

interface EpochMilliseconds {
  epochMilliseconds: number;
}

Source

View source on GitHub