Date.prototype.valueOf()

The valueOf() method of {{jsxref("Date")}} instances returns the number of milliseconds for this date since the epoch, which is defined as the midnight at the beginning of January 1, 1970, UTC.

{{InteractiveExample("JavaScript Demo: Date.prototype.valueOf()")}}

```js interactive-example const date1 = new Date(Date.UTC(96, 1, 2, 3, 4, 5));

console.log(date1.valueOf()); // Expected output: 823230245000

const date2 = new Date("02 Feb 1996 03:04:05 GMT");

console.log(date2.valueOf()); // Expected output: 823230245000

## Syntax

```js-nolint
valueOf()

Parameters#

None.

Return value#

A number representing the timestamp, in milliseconds, of this date. Returns NaN if the date is invalid.

Description#

The valueOf() method is part of the type coercion protocol. Because Date has a [Symbol.toPrimitive]() method, that method always takes priority over valueOf() when a Date object is implicitly coerced to a number. However, Date.prototype[Symbol.toPrimitive]() still calls this.valueOf() internally.

The {{jsxref("Date")}} object overrides the {{jsxref("Object/valueOf", "valueOf()")}} method of {{jsxref("Object")}}. Date.prototype.valueOf() returns the timestamp of the date, which is functionally equivalent to the {{jsxref("Date.prototype.getTime()")}} method.

Examples#

Using valueOf()#

const d = new Date(0); // 1970-01-01T00:00:00.000Z
console.log(d.valueOf()); // 0

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("Object.prototype.valueOf()")}}
• {{jsxref("Date.prototype.getTime()")}}