toMillis

Converts a date to a timestamp in milliseconds (epoch millis).

Use this when you need a plain number from a DateLike value (e.g. for Date.now() comparisons, localStorage, or JS-native APIs).

Available since v2.0.0

Import

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

Signature

toMillis(date: DateLike): number | null

Parameters

Parameter	Type	Description
date	DateLike	The date to convert

Returns

number | null — Milliseconds since the Unix epoch, or null for invalid input

Examples

toMillis

toMillis('2025-01-19T12:00:00Z') // => 1737288000000
toMillis(null)                    // => null

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