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Date.prototype.valueOf()

The valueOf() method of 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.

Try it

Syntax

js
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 [@@toPrimitive]() method, that method always takes priority over valueOf() when a Date object is implicitly coerced to a number. However, Date.prototype[@@toPrimitive]() still calls this.valueOf() internally.

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

Examples

Using valueOf()

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

Specifications

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android Deno Node.js
valueOf 1 12 1 3 1 18 4 10.1 1 1.0 4.4 1.0 0.10.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/valueOf