date-fns

date-fns is a library for manipulating native Dates in JavaScript

Installation

Install the usual way:

npm install date-fns

# Sibling library for timezone-functions https://github.com/marnusw/date-fns-tz
npm install date-fns-tz

# For an alternative to this that is still under date-fns https://github.com/date-fns/tz
npm install @date-fns/tz

Usage

Stolen from their documentation, use like:

import { format, compareAsc } from "date-fns";

// "02/11/2014"
format(new Date(2014, 1, 11), "MM/dd/yyyy");

const dates = [
  new Date(1995, 6, 2),
  new Date(1987, 1, 11),
  new Date(1989, 6, 10),
];

// [
//   Wed Feb 11 1987 00:00:00,
//   Mon Jul 10 1989 00:00:00,
//   Sun Jul 02 1995 00:00:00,
// ]
dates.sort(compareAsc);

For all format() options including accepted patterns, see their documentation.

date-fns exposes many different constants, like:

// 3600000
millisecondsInHour

// 43200
minutesInMonth

// 365.2425
daysInYear

Manipulate dates like:

import { sub, add } from "date-fns";

const startTime = new Date(2025, 1, 1);
const eventDurationHours = 6;

const openingTime = sub(startTime, { minutes: 45 });
const closingTime = add(startTime, { hours: eventDurationHours });

Format relative time using their formatRelative:

// "last Thursday at 12:45 AM"
const result = formatRelative(subDays(new Date(), 6), new Date())

For options for formatRelative, see the documentation.

Format durations using their formatDuration:

// "9 months 2 days"
formatDuration({ months: 9, days: 2 })