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eachDay

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

Both boundaries are included. If start > end, an empty array is returned. Returns an empty array if either input is invalid.

Available since v2.0.0

import { eachDay } from '@helpers4/date';
eachDay(start: DateLike, end: DateLike): Date[]
ParameterTypeDescription
startDateLikeStart date (inclusive)
endDateLikeEnd date (inclusive)

Date[] — An array of Date objects, one per day

eachDay('2025-01-01', '2025-01-03')
// => [Date(2025-01-01), Date(2025-01-02), Date(2025-01-03)]

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

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;
}

View source on GitHub