Date.setMonth()

Sets the month of a date object

The setMonth() method sets the month for a specified date according to the currently set year.

var event = new Date('August 19, 1975 23:15:30');

event.setMonth(3);

console.log(event.getMonth());
// expected output: 3

console.log(event);
// Sat Apr 19 1975 23:15:30 GMT+0100 (CET)
// (note: your timezone may vary)

Syntax

dateObj.setMonth(monthValue[, dayValue])

Versions prior to JavaScript 1.3

dateObj.setMonth(monthValue)

Parameters

monthValueAn integer between 0 and 11, representing the months January through December.

dayValueOptional. An integer from 1 to 31, representing the day of the month.

Return value

The number of milliseconds between 1 January 1970 00:00:00 UTC and the updated date.

Description

If you do not specify the dayValue parameter, the value returned from the getDate()method is used.

If a parameter you specify is outside of the expected range, setMonth() attempts to update the date information in the Date object accordingly. For example, if you use 15 for monthValue, the year will be incremented by 1, and 3 will be used for month.

The current day of month will have an impact on the behaviour of this method. Conceptually it will add the number of days given by the current day of the month to the 1st day of the new month specified as the parameter, to return the new date. For example, if the current value is 31st August 2016, calling setMonth with a value of 1 will return 2nd March 2016. This is because in 2016 February had 29 days.

Examples

Using setMonth()

var theBigDay = new Date();
theBigDay.setMonth(6);

//Watch out for end of month transitions
var endOfMonth = new Date(2016, 7, 31);
endOfMonth.setMonth(1);
console.log(endOfMonth); //Wed Mar 02 2016 00:00:00

References

Date.prototype.setMonth() - JavaScript | MDN

Contributors to this page

Uros Durdevic