JavaScript - add years to date

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Created by:

Saim-Mccullough

688

In this article, we would like to show you how to add years 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 years,
years - a number of years we want to add.

Runnable example:

// ONLINE-RUNNER:browser;

const addYears = (date, years) => {
  let result = new Date(date);
  result.setFullYear(result.getFullYear() + years);
  return result;
};

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

console.log(addYears(date, 1).toISOString());  // 2022-08-30T08:00:00.000Z

Output:

2022-08-30T08:00:00.000Z

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.addYears = function (years) {
  let date = new Date(this.valueOf());
  date.setFullYear(date.getFullYear() + years);
  return date;
};

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

console.log(date.addYears(4).toISOString());

Output: