How to Reliably Add Months to a JavaScript Date?

How to Add Months to a JavaScript Date

Adding months to a JavaScript date can be a tricky task if you want to handle year roll-overs and varying month lengths correctly. To simplify the process, consider utilizing a pre-built function.

The following JavaScript function provides a clean and straightforward solution (taken from this source):

Function: addMonths(date, months)

Description:

• Takes a JavaScript Date object as input (date).
• Adds a specified number of months (months) to the date.
• Handles year roll-overs and adjusts for varying month lengths automatically.
• Returns a new Date object with the modified date.

Example Usage:

// 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());

Output:

Sat Feb 28 00:00:00 GMT+0000 2017
Sun Dec 01 00:00:00 GMT+0000 2016
Wed Nov 30 00:00:00 GMT+0000 2016
Tue Feb 28 00:00:00 GMT+0000 2017

This function simplifies the task of adding months to a JavaScript date, providing reliable results without the need for complex date calculations.

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