constructor
new Date()
Creates a Date object representing a single moment in time as milliseconds since the Unix epoch (1970-01-01T00:00:00Z). Called with no arguments it returns the current instant; with arguments it parses a timestamp, ISO string, or component parts.
new Date([value])Parameters
| Parameter | Purpose |
|---|---|
| () | current date/time from the system clock |
| (ms) | milliseconds since Unix epoch (number) |
| (isoString) | ISO 8601 string, e.g. '2026-07-19T12:00:00Z' |
| (y, m, d, h, mi, s, ms) | component parts in LOCAL time; month is 0-11 |
Examples
console.log(new Date().toISOString());current UTC instant
console.log(new Date(0).toISOString()); // '1970-01-01T00:00:00.000Z'Unix epoch
console.log(new Date(2026, 6, 19).toDateString()); // 'Sun Jul 19 2026'month 6 = July (0-indexed)
console.log(new Date('2026-07-19T00:00:00Z').getUTCDate()); // 19ISO string parsed as UTC
Gotcha
The component-parts form uses 0-indexed months (Jan=0, Dec=11) and is interpreted in the LOCAL timezone; an ISO date-only string 'YYYY-MM-DD' is parsed as UTC while 'YYYY-MM-DDTHH:mm:ss' without a Z is local.
Related
Date.now
Returns the current time as an integer number of milliseconds since the Unix epoch without allocating a Date object. Use it for timestamps, expiry checks, and simple timing.
Date.parse
Parses a date string and returns the corresponding milliseconds since the Unix epoch, or NaN if unrecognized. Only the ISO 8601 subset is guaranteed portable; any other format is implementation-defined.
Date.UTC
Returns the milliseconds since the Unix epoch for the given components interpreted as UTC. Unlike the Date component constructor, it does not apply the local timezone.