endOf

Returns a new Date set to the end of the given unit.

• 'day' — 23:59:59.999
• 'month' — last day of the month, 23:59:59.999
• 'year' — December 31st, 23:59:59.999

Returns null if the input is invalid.

Available since v2.0.0

Import

import { endOf } from '@helpers4/date';
// or, from the all-in-one package (same code, one install):
import { endOf } from 'helpers4/date';

Signature

endOf(date: DateLike, unit: DateTruncUnit): Date | null

Parameters

Parameter	Type	Description
date	DateLike	The base date
unit	DateTruncUnit	The unit to round to

Returns

Date | null — A new Date at the end of the unit, or null

Examples

endOf

endOf('2025-06-15T14:30:00Z', 'day')    // => 2025-06-15T23:59:59.999Z
endOf('2025-06-15T14:30:00Z', 'month')  // => 2025-06-30T23:59:59.999Z
endOf('2025-06-15T14:30:00Z', 'year')   // => 2025-12-31T23:59:59.999Z

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)
• Temporal.Instant | Temporal.ZonedDateTime — read via their epochMilliseconds property

type DateLike = Date | number | string | Temporal.Instant | Temporal.ZonedDateTime

DateTruncUnit

Units supported by startOf and endOf.

type DateTruncUnit = 'day' | 'month' | 'year'

Source

View source on GitHub