date-fns, datejs, dayjs, luxon, and moment are JavaScript libraries designed to simplify working with dates and times in web applications. They provide utilities for parsing, formatting, validating, and manipulating date values across different time zones and locales. While all aim to address the limitations of JavaScript’s native Date object, they differ significantly in architecture, mutability behavior, internationalization support, and current maintenance status.
JavaScript Date Libraries Compared: date-fns, datejs, dayjs, luxon, and moment
Working with dates in JavaScript is notoriously tricky due to the limitations of the native Date object—especially around parsing, formatting, time zones, and immutability. Over the years, several libraries have emerged to fill this gap. Let’s compare the five most notable ones: date-fns, datejs, dayjs, luxon, and moment. We’ll focus on real-world usage, API design, and whether they’re still viable today.
⚠️ Deprecation Status: What’s Still Safe to Use?
Before diving into features, it’s critical to know which libraries are actively maintained:
datejsis deprecated. Its last official release was in 2010, and the project is archived on GitHub. Do not use it in new code.momentis in legacy maintenance mode. The team recommends against using it in new projects and points developers to alternatives likedate-fnsorluxon.date-fns,dayjs, andluxonare actively maintained and suitable for production use.
🧩 Core Philosophy: Mutable vs Immutable vs Functional
How each library handles date mutation affects predictability and debugging.
date-fns uses a pure functional approach. Every function takes a Date object and returns a new one—never mutating the input.
// date-fns
import { addDays, format } from 'date-fns';
const today = new Date();
const tomorrow = addDays(today, 1);
console.log(format(tomorrow, 'yyyy-MM-dd')); // e.g., "2024-06-15"
dayjs follows an immutable chainable pattern similar to Moment, but always returns a new instance.
// dayjs
import dayjs from 'dayjs';
const today = dayjs();
const tomorrow = today.add(1, 'day');
console.log(tomorrow.format('YYYY-MM-DD')); // e.g., "2024-06-15"
luxon uses immutable DateTime objects. All operations return new instances.
// luxon
import { DateTime } from 'luxon';
const today = DateTime.now();
const tomorrow = today.plus({ days: 1 });
console.log(tomorrow.toFormat('yyyy-MM-dd')); // e.g., "2024-06-15"
moment (legacy) uses mutable objects by default, though methods like .add() return new instances in newer versions. However, its API encourages side effects.
// moment (avoid in new projects)
import moment from 'moment';
const today = moment();
const tomorrow = today.clone().add(1, 'day'); // must clone to avoid mutation
console.log(tomorrow.format('YYYY-MM-DD'));
datejs (deprecated) modifies the original Date object directly, leading to hard-to-track bugs.
// datejs — DO NOT USE
Date.today().addDays(1); // mutates global Date prototype!
🌍 Time Zone Support: Where Things Get Complicated
Time zone handling separates mature libraries from basic ones.
luxon has first-class timezone support using the browser’s built-in Intl API. No external data needed.
// luxon
const ny = DateTime.now().setZone('America/New_York');
const london = ny.setZone('Europe/London');
console.log(ny.toISO(), london.toISO());
date-fns supports time zones via the optional date-fns-tz plugin, which also relies on Intl.
// date-fns + date-fns-tz
import { zonedTimeToUtc, utcToZonedTime, format } from 'date-fns-tz';
const utcDate = zonedTimeToUtc('2024-06-14 12:00', 'America/New_York');
const londonTime = utcToZonedTime(utcDate, 'Europe/London');
console.log(format(londonTime, 'yyyy-MM-dd HH:mm', { timeZone: 'Europe/London' }));
dayjs requires the timezone plugin and either preloaded IANA data or reliance on the browser’s Intl.
// dayjs + timezone plugin
import dayjs from 'dayjs';
import utc from 'dayjs/plugin/utc';
import timezone from 'dayjs/plugin/timezone';
dayjs.extend(utc);
dayjs.extend(timezone);
const ny = dayjs().tz('America/New_York');
const london = ny.tz('Europe/London');
console.log(london.format());
moment needs the separate moment-timezone package with bundled timezone data—adding significant weight.
// moment-timezone (legacy)
import moment from 'moment-timezone';
const ny = moment.tz('2024-06-14 12:00', 'America/New_York');
const london = ny.clone().tz('Europe/London');
console.log(london.format());
datejs has no timezone support whatsoever.
📦 Bundle Size and Tree-Shaking
For frontend apps, how much code you ship matters.
date-fnsis fully tree-shakable. You only import the functions you use.dayjsis tiny by default (~2KB), and plugins are added selectively.luxonis larger (~7–10KB) but includes robust timezone logic without extra plugins.momentships its entire locale and timezone data unless carefully pruned (which is hard).datejsis small but obsolete and unsafe.
🌐 Internationalization (i18n) and Locales
All active libraries support multiple languages, but implementation differs.
date-fns uses locale objects passed as options:
import { format } from 'date-fns';
import { es } from 'date-fns/locale';
format(new Date(), 'PPPP', { locale: es }); // Spanish long date
dayjs requires registering locales:
import dayjs from 'dayjs';
import 'dayjs/locale/es';
dayjs.locale('es');
console.log(dayjs().format('dddd, MMMM D')); // Spanish
luxon uses the Intl API, so it respects the user’s system locale or accepts a locale option:
DateTime.now().toLocaleString({ locale: 'es' });
moment loads locales dynamically but bloats the bundle if not managed carefully.
🔁 Parsing and Formatting Syntax
Each library has its own token system.
| Format Goal | date-fns | dayjs | luxon | moment |
|---|---|---|---|---|
| Year-Month-Day | yyyy-MM-dd | YYYY-MM-DD | yyyy-MM-dd | YYYY-MM-DD |
| Full Weekday | EEEE | dddd | EEEE | dddd |
| 12-Hour Time | hh:mm a | hh:mm A | hh:mm a | hh:mm A |
Note: luxon and date-fns align closely with Unicode Technical Standard #35; dayjs and moment follow older conventions.
🧪 Real-World Recommendation Scenarios
Scenario 1: Lightweight App with Basic Date Needs
You need to format dates, add days, and parse ISO strings—no time zones.
- ✅ Best choice:
dayjsordate-fns - Why? Both are small, fast, and cover 90% of use cases without overhead.
Scenario 2: Global SaaS Application with Time Zones
Users in Tokyo, London, and New York need accurate local times.
- ✅ Best choice:
luxon - Why? Built-in, standards-compliant timezone handling with no extra data bundles.
Scenario 3: Legacy Codebase Using Moment
You’re maintaining an old app and can’t rewrite everything at once.
- ✅ Strategy: Keep
momenttemporarily, but plan migration todate-fnsordayjs. - Use codemods to automate conversion where possible.
Scenario 4: Server-Side Rendering with Locale Support
You render localized dates on the server using Node.js.
- ✅ Best choice:
date-fns(withdate-fns-tzif needed) - Why? Works reliably in Node without browser APIs; locales are explicit and modular.
📊 Summary Table
| Feature | date-fns | datejs | dayjs | luxon | moment |
|---|---|---|---|---|---|
| Status | ✅ Active | ❌ Deprecated | ✅ Active | ✅ Active | ⚠️ Legacy |
| Immutability | ✅ Pure functions | ❌ Mutable | ✅ Immutable | ✅ Immutable | ⚠️ Mostly mutable |
| Tree-shaking | ✅ Full | N/A | ✅ Partial | ❌ No | ❌ No |
| Time Zones | ✅ (via plugin) | ❌ None | ✅ (via plugin) | ✅ Built-in | ✅ (heavy plugin) |
Uses Native Date | ✅ Yes | ✅ Yes | ❌ Custom wrapper | ❌ DateTime obj | ❌ Custom wrapper |
| Locale Support | ✅ Modular | ❌ Limited | ✅ Plugin-based | ✅ Intl-based | ✅ Bundled |
💡 Final Guidance
- New projects: Start with
date-fnsfor simplicity and performance, orluxonif you need serious timezone work. - Moment users: Begin migrating—your future self will thank you.
- Never use
datejs—it’s a relic with known flaws.
The JavaScript date ecosystem has matured. Today’s tools are faster, safer, and more aligned with modern web standards. Choose wisely, and your date logic will be far less painful.
- date-fns:
Choose
date-fnsif you need a functional, immutable, and tree-shakable library with excellent performance and broad feature coverage. It uses nativeDateobjects under the hood and avoids custom date wrappers, making it easy to integrate with existing code. Ideal for modern applications where bundle size and modularity matter. - dayjs:
Choose
dayjsif you want a lightweight, Moment.js-like API with minimal bundle size and plugin-based extensibility. It uses a chainable, mutable-like syntax but returns new instances (immutable by design). Best for projects that value familiarity with Moment’s patterns but require better performance and smaller footprint. - moment:
Avoid
momentfor new projects. Although historically dominant, it is now in legacy maintenance mode with no new features planned. Its large bundle size, mutable API, and lack of tree-shaking make it unsuitable for modern frontend applications. Migrate todate-fns,dayjs, orluxoninstead. - luxon:
Choose
luxonif your application requires robust timezone handling using the browser’s Intl API, immutable date objects, and modern standards compliance. Built on top of theIntlAPI, it avoids external dependencies for timezone data and integrates well with environments that support modern JavaScript features. - datejs:
Do not choose
datejsfor new projects. The library has been officially deprecated since 2010 and is no longer maintained. Its API is outdated, lacks timezone support, and contains known bugs. Usedate-fns,dayjs, orluxoninstead.
🔥️ NEW: date-fns v4.0 with first-class time zone support is out!
date-fns provides the most comprehensive, yet simple and consistent toolset for manipulating JavaScript dates in a browser & Node.js
👉 Blog
It's like Lodash for dates
- It has 200+ functions for all occasions.
- Modular: Pick what you need. Works with webpack, Browserify, or Rollup and also supports tree-shaking.
- Native dates: Uses existing native type. It doesn't extend core objects for safety's sake.
- Immutable & Pure: Built using pure functions and always returns a new date instance.
- TypeScript: The library is 100% TypeScript with brand-new handcrafted types.
- I18n: Dozens of locales. Include only what you need.
- and many more benefits
import { compareAsc, format } from "date-fns";
format(new Date(2014, 1, 11), "yyyy-MM-dd");
//=> '2014-02-11'
const dates = [
new Date(1995, 6, 2),
new Date(1987, 1, 11),
new Date(1989, 6, 10),
];
dates.sort(compareAsc);
//=> [
// Wed Feb 11 1987 00:00:00,
// Mon Jul 10 1989 00:00:00,
// Sun Jul 02 1995 00:00:00
// ]
The library is available as an npm package. To install the package run:
npm install date-fns --save
Docs
See date-fns.org for more details, API, and other docs.