Date.prototype.setDate()

Try it

const event = new Date("August 19, 1975 23:15:30");

event.setDate(24);

console.log(event.getDate());
// Expected output: 24

event.setDate(32);
// Only 31 days in August!

console.log(event.getDate());
// Expected output: 1

Syntax

setDate(dateValue)

Parameters

dateValue

An integer representing the day of the month.

Return value

Changes the Date object in place, and returns its new timestamp. If dateValue 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 specify a number outside the expected range, the date information in the Date object is updated accordingly. For example, if the Date object holds June 1st, a dateValue of 40 changes the date to July 10th, while a dateValue of 0 changes the date to the last day of the previous month, May 31st.

Because setDate() 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 date 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 day difference multiplied by 24 hours. 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 setUTCDate() or 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 setDate()

const theBigDay = new Date(1962, 6, 7, 12); // noon of 1962-07-07 (7th of July 1962, month is 0-indexed)
const theBigDay2 = new Date(theBigDay).setDate(24); // 1962-07-24 (24th of July 1962)
const theBigDay3 = new Date(theBigDay).setDate(32); // 1962-08-01 (1st of August 1962)
const theBigDay4 = new Date(theBigDay).setDate(22); // 1962-07-22 (22nd of July 1962)
const theBigDay5 = new Date(theBigDay).setDate(0); // 1962-06-30 (30th of June 1962)
const theBigDay6 = new Date(theBigDay).setDate(98); // 1962-10-06 (6th of October 1962)
const theBigDay7 = new Date(theBigDay).setDate(-50); // 1962-05-11 (11th of May 1962)

Specifications

Browser compatibility

See also

• Date()
• Date.prototype.getDate()
• Date.prototype.setUTCDate()