date-fns vs dayjs | Date and Time Manipulation Comparison

Package	Downloads	Stars	Size	Issues	Publish	License

date-fns	26,626,434	35,310	22.6 MB	792	5 months ago	MIT
dayjs	23,593,553	47,448	670 kB	1,077	6 months ago	MIT

Package

Downloads

Stars

Size

Issues

Publish

License

date-fns

26,626,434

35,310

22.6 MB

792

5 months ago

MIT

dayjs

23,593,553

47,448

670 kB

1,077

6 months ago

MIT

Size and Performance

date-fns:
date-fns is designed with performance in mind, and its modular nature allows you to import only the functions you need, which can lead to smaller bundle sizes compared to monolithic libraries. However, the performance may vary depending on the specific functions used.
dayjs:
Day.js is significantly smaller in size (about 2KB minified and gzipped), making it a great choice for performance-sensitive applications. Its lightweight nature means faster load times and lower bandwidth usage, which is crucial for mobile applications and sites with many users.

API Design

date-fns:
date-fns provides a simple and consistent API for date manipulation, but it follows a more functional programming style, which may require a slight adjustment for developers used to object-oriented approaches. The API is well-documented and easy to understand.
dayjs:
Day.js has a modern and intuitive API that is designed to be chainable and easy to use. It mimics the Moment.js API, making it easy for developers familiar with Moment.js to transition. Its simplicity allows for quick date manipulations without much overhead.

Mutability

date-fns:
date-fns functions are immutable, meaning they do not modify the original date objects. Instead, they return new instances with the desired changes, which helps prevent side effects and makes the code more predictable.
dayjs:
Day.js is immutable, meaning that any operations performed on a Day.js object return a new instance rather than modifying the original object. This immutability helps prevent side effects and makes the code easier to reason about, especially in functional programming contexts.

Localization and Time Zones

date-fns:
date-fns has good support for localization, and it allows you to easily format dates in different languages. However, time zone support is limited, and you may need to use additional libraries for more complex time zone manipulations.
dayjs:
Day.js supports localization through plugins, allowing developers to add only the locales they need, which keeps the bundle size small. However, its time zone support is limited compared to Moment.js, requiring additional plugins for full functionality.

Community and Maintenance

date-fns:
date-fns has a strong and active community, and it is regularly maintained with updates and new features. Its focus on modularity and performance has made it a popular choice among developers.
dayjs:
Day.js has a growing community and is actively maintained, with a focus on performance and simplicity. Its modern approach and smaller size have attracted a lot of attention, making it a popular choice for new projects.

Ease of Use: Code Examples

date-fns:

date-fns example

import { format, parseISO } from 'date-fns';

const date = parseISO('2023-01-01');
const formattedDate = format(date, 'MMMM dd, yyyy');
console.log(formattedDate); // January 01, 2023

dayjs:

time zone support in dayjs

import dayjs from 'dayjs';
console.log(dayjs().format('YYYY-MM-DD'));

// Using a plugin
import timezone from 'dayjs/plugin/timezone';
dayjs.extend(timezone);
console.log(dayjs().tz('America/New_York').format());

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 // ]