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


dateObj.setMonth(monthValue[, dayValue])

Versions prior to JavaScript 1.3



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


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.


Using setMonth()

var theBigDay = new Date();

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




Specification Status Comment
ECMAScript 1st Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.0.
ECMAScript 5.1 (ECMA-262)
The definition of 'Date.prototype.setMonth' in that specification.
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Date.prototype.setMonth' in that specification.
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Date.prototype.setMonth' in that specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (Yes) (Yes) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

Document Tags and Contributors

 Last updated by: shafalfa,