Date.prototype.setHours()

The setHours() method of {{jsxref("Date")}} instances changes the hours, minutes, seconds, and/or milliseconds for this date according to local time.

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

```js interactive-example const event = new Date("August 19, 1975 23:15:30"); event.setHours(20);

console.log(event); // Expected output: "Tue Aug 19 1975 20:15:30 GMT+0200 (CEST)" // Note: your timezone may vary

event.setHours(20, 21, 22);

console.log(event); // Expected output: "Tue Aug 19 1975 20:21:22 GMT+0200 (CEST)"

## Syntax

```js-nolint
setHours(hoursValue)
setHours(hoursValue, minutesValue)
setHours(hoursValue, minutesValue, secondsValue)
setHours(hoursValue, minutesValue, secondsValue, msValue)

Parameters#

• hoursValue
• : An integer between 0 and 23 representing the hours.
• minutesValue {{optional_inline}}
• : An integer between 0 and 59 representing the minutes.
• secondsValue {{optional_inline}}
• : An integer between 0 and 59 representing the seconds. If you specify secondsValue, you must also specify minutesValue.
• msValue {{optional_inline}}
• : An integer between 0 and 999 representing the milliseconds. If you specify msValue, you must also specify minutesValue and secondsValue.

Return value#

Changes the {{jsxref("Date")}} object in place, and returns its new timestamp. If a parameter is NaN (or other values that get coerced to NaN, such as undefined), the date is set to Invalid Date and NaN is returned.

Description#

If you do not specify the minutesValue, secondsValue, and msValue parameters, the same values as what are returned by {{jsxref("Date/getMinutes", "getMinutes()")}}, {{jsxref("Date/getSeconds", "getSeconds()")}}, and {{jsxref("Date/getMilliseconds", "getMilliseconds()")}} are used.

If a parameter you specify is outside of the expected range, other parameters and the date information in the {{jsxref("Date")}} object are updated accordingly. For example, if you specify 100 for secondsValue, the minutes are incremented by 1 (minutesValue + 1), and 40 is used for seconds.

Because setHours() operates on the local time, crossing a Daylight Saving Time (DST) boundary may result in a different elapsed time than expected. For example, if setting the hours crosses a spring-forward transition (losing an hour), the difference in timestamps between the new and old date is one hour less than the nominal hour difference. Conversely, crossing a fall-back transition (gaining an hour) result in an extra hour. If you need to adjust the date by a fixed amount of time, consider using {{jsxref("Date/setUTCHours", "setUTCHours()")}} or {{jsxref("Date/setTime", "setTime()")}}.

If the new local time falls within an offset transition, the exact time is derived using the same behavior as Temporal's disambiguation: "compatible" option. That is, if the local time corresponds to two instants, the earlier one is chosen; if the local time does not exist (there is a gap), we go forward by the gap duration.

Examples#

Using setHours()#

const theBigDay = new Date();
theBigDay.setHours(7);

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("Date.prototype.getHours()")}}
• {{jsxref("Date.prototype.setUTCHours()")}}