JavaScript - subtract days from date

In this article, we would like to show you how to subtract days from date in JavaScript.

Quick solution:

// ONLINE-RUNNER:browser;

const date = new Date('2021-06-30');
date.setDate(date.getDate() - 2);  // subtracted 2 days from existing date

console.log(date.toISOString());   // 2021-06-28T00:00:00.000Z

or:

// ONLINE-RUNNER:browser;

const date = new Date('2021-06-30');
const newDate = new Date(date.getTime() - 2 * (24 * 60 * 60 * 1000));  // subtracted 2 days from existing date

console.log(newDate.toISOString());  // 2021-06-28T00:00:00.000Z

1.  Example reusable lambda function

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

• date from which we want to subtract some days,
• days - a number of days we want to subtract.

Runnable example:

// ONLINE-RUNNER:browser;

const subtractDays = (date, days) => {
  let result = new Date(date);
  result.setDate(result.getDate() - days);
  return result;
};

let date = new Date('2021-06-30');
let result = subtractDays(date, 3);

console.log(result.toISOString());  // 2021-06-27T00:00:00.000Z

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.subtractDays = function (days) {
  let date = new Date(this.valueOf());
  date.setDate(date.getDate() - days);
  return date;
};

let date = new Date('2021-06-30');
let result = date.subtractDays(2)

console.log(result.toISOString());  // 2021-06-28T00:00:00.000Z