JavaScript - add months to date

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Created by:

Anisha-Kidd

652

In this article, we would like to show you how to add months to date in JavaScript.

1. Example reusable lambda function

In this example, we create a simple function that takes two arguments:

date to which we want to add some months,
months - a number of months we want to add.

Runnable example:

// ONLINE-RUNNER:browser;

const addMonths = (date, months) => {
  let result = new Date(date);
  result.setMonth(result.getMonth() + months);
  return result;
};

let date = new Date('2021-08-30T08:00:00.000Z');

console.log(addMonths(date, 1).toISOString());  // 2021-09-30T08:00:00.000Z

Output:

2021-09-30T08:00:00.000Z

2. Extending existing `Date` class with `Date.prototype`

In this example, we add a function to the Date.prototype so we can use it on any date object.

// ONLINE-RUNNER:browser;

Date.prototype.addMonths = function (months) {
  let date = new Date(this.valueOf());
  date.setMonth(date.getMonth() + months);
  return date;
};

let date = new Date('2021-08-30T08:00:00.000Z');

console.log(date.addMonths(2).toISOString());  // 2021-10-30T08:00:00.000Z

Output: