The following function adds months to a date in JavaScript (source). It takes into account year roll-overs and varying month lengths:
function addMonths(date, months) {
var d = date.getDate();
date.setMonth(date.getMonth() + +months);
if (date.getDate() != d) {
date.setDate(0);
}
return date;
}
// Add 12 months to 29 Feb 2016 -> 28 Feb 2017
console.log(addMonths(new Date(2016,1,29),12).toString());
// Subtract 1 month from 1 Jan 2017 -> 1 Dec 2016
console.log(addMonths(new Date(2017,0,1),-1).toString());
// Subtract 2 months from 31 Jan 2017 -> 30 Nov 2016
console.log(addMonths(new Date(2017,0,31),-2).toString());
// Add 2 months to 31 Dec 2016 -> 28 Feb 2017
console.log(addMonths(new Date(2016,11,31),2).toString());
The above solution covers the edge case of moving from a month with a greater number of days than the destination month. eg.
- Add twelve months to February 29th 2020 (should be February 28th 2021)
- Add one month to August 31st 2020 (should be September 30th 2020)
If the day of the month changes when applying setMonth
, then we know we have overflowed into the following month due to a difference in month length. In this case, we use setDate(0)
to move back to the last day of the previous month.
Note: this version of this answer replaces an earlier version (below) that did not gracefully handle different month lengths.
var x = 12; //or whatever offset
var CurrentDate = new Date();
console.log("Current date:", CurrentDate);
CurrentDate.setMonth(CurrentDate.getMonth() + x);
console.log("Date after " + x + " months:", CurrentDate);