JavaScript - subtract milliseconds from date

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

Quick solution:

// ONLINE-RUNNER:browser;

let date = new Date('2021-08-30T00:00:00.000Z');
date.setMilliseconds(date.getMilliseconds() - 5);

console.log(date.toISOString());  // 2021-08-29T23:59:59.995Z

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 milliseconds,
• milliseconds - a number of milliseconds we want to subtract.

Runnable example:

// ONLINE-RUNNER:browser;

const subtractMilliseconds = (date, milliseconds) => {
  const result = new Date(date);
  result.setMilliseconds(result.getMilliseconds() - milliseconds);
  return result;
};

let date = new Date('2021-08-30T00:00:00.000Z');

console.log(subtractMilliseconds(date, 5).toISOString());  // 2021-08-29T23:59:59.995Z

Output:

2021-08-29T23:59:59.995Z

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.subtractMilliseconds = function (milliseconds) {
  let date = new Date(this.valueOf());
  date.setMilliseconds(date.getMilliseconds() - milliseconds);
  return date;
};

let date = new Date('2021-08-30T00:00:00.000Z');

console.log(date.subtractMilliseconds(5).toISOString());  // 2021-08-29T23:59:59.995Z

Output: 

2021-08-29T23:59:59.995Z