date-fns

Overview

date-fns is an open-source JavaScript library that provides a comprehensive and consistent toolset for working with dates and times. Established in 2014, it distinguishes itself by offering over 200 functions for common date operations, including parsing, formatting, validation, and arithmetic. Unlike some other date libraries, date-fns operates directly on native JavaScript Date objects, avoiding the creation of custom wrapper objects. This design choice simplifies interoperability with existing JavaScript codebases and can reduce the learning curve for developers already familiar with the native Date API.

The library's architecture is highly modular, with each function existing as an independent module. This modularity is a core feature, enabling effective tree-shaking during the build process, which helps to reduce the final bundle size of web applications by including only the functions that are actively used. This is particularly beneficial for modern JavaScript projects where performance and efficient resource loading are critical considerations. date-fns also fully supports TypeScript, offering type definitions that enhance developer experience by providing autocompletion and compile-time error checking.

date-fns is particularly well-suited for applications that require robust internationalization (i18n) capabilities, as it provides locale data for numerous languages, allowing dates to be formatted and displayed according to specific regional conventions. Its functional programming paradigm encourages immutable data operations, meaning functions typically return new date objects instead of modifying existing ones. This approach can lead to more predictable code and simplify debugging by preventing unintended side effects. Developers targeting modern browsers and Node.js environments often choose date-fns for its balance of features, performance, and adherence to modern JavaScript best practices.

The library's design principles align with web standards and native browser APIs, promoting a lightweight footprint and efficient execution. For instance, when comparing date-fns with alternatives like Moment.js, a key difference is date-fns's commitment to immutability and direct Date object manipulation, which contrasts with Moment.js's mutable design and wrapper object approach. This distinction is often highlighted in performance and bundle size discussions within the JavaScript ecosystem, as noted in various comparisons and developer discussions on library choices for date handling.

Key features

• Modular Design: Each function is a standalone module, enabling tree-shaking for optimized bundle sizes. For example, importing format does not automatically include addDays, leading to smaller application footprints.
• Native Date Object Usage: Operates directly on JavaScript's built-in Date objects, avoiding custom wrapper classes and simplifying integration with existing code. This ensures consistency with native JavaScript behavior.
• Immutable Functions: All functions return new date instances instead of modifying existing ones, promoting predictable code and reducing side effects in applications. This aligns with functional programming principles.
• Comprehensive Function Set: Offers over 200 functions for a wide range of date and time operations, including formatting, parsing, arithmetic (e.g., adding days, subtracting months), comparisons, and validation. The date-fns documentation provides a complete list of available utilities.
• Internationalization (i18n): Includes extensive locale support, allowing dates to be formatted and displayed according to specific cultural and regional conventions. This is critical for global applications.
• TypeScript Support: Fully compatible with TypeScript, providing type definitions that enhance developer productivity with autocompletion, type checking, and improved code maintainability.
• RFC 3339 Support: Handles date and time formatting according to RFC 3339, a profile of ISO 8601 for use in Internet protocols, ensuring compatibility with various APIs and data exchange formats.

Pricing

date-fns is distributed under the MIT License, making it a free and open-source library. There are no licensing fees, subscription costs, or paid tiers associated with its use. All features, updates, and community support are available without charge.

Common integrations

date-fns is a general-purpose JavaScript library, and as such, it integrates seamlessly into virtually any JavaScript or TypeScript project. Its functional nature and direct use of native Date objects make it highly compatible with various frameworks and build tools.

• React/Vue/Angular: Easily integrates into component-based UI frameworks for displaying formatted dates, calculating time differences, or handling date inputs. For example, a React component can use format(new Date(), 'yyyy-MM-dd') directly.
• Node.js Backend Services: Utilized in server-side applications for processing timestamps, scheduling tasks, formatting dates for API responses, or performing date-based database queries.
• Webpack/Rollup/Vite: Optimized for modern bundlers, which can effectively tree-shake unused functions, leading to smaller production bundles.
• TypeScript Projects: Provides comprehensive type definitions out-of-the-box, enhancing developer experience and code reliability in TypeScript applications. The date-fns Getting Started guide details TypeScript setup.
• UI Component Libraries: Often used internally by or alongside UI libraries (e.g., Material UI, Ant Design) that require robust date manipulation for date pickers, calendars, and timelines.

Alternatives

• Moment.js: A popular, mature JavaScript date library known for its mutable API and extensive feature set, though it has a larger bundle size and is no longer actively developed for new features.
• Luxon: A modern, immutable date and time library built by the Moment.js team, offering better internationalization and time zone support with an immutable API.
• Day.js: A minimalist JavaScript library that parses, validates, manipulates, and displays dates and times. It is designed to be a lightweight alternative to Moment.js with a similar API.

Getting started

To begin using date-fns in a JavaScript or TypeScript project, install it via npm or yarn. Once installed, you can import individual functions as needed, which benefits tree-shaking. The following example demonstrates how to install date-fns and then use it to format the current date and add five days to it.

npm install date-fns
# or
yarn add date-fns

After installation, you can import and use specific functions:

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

// Get the current date
const today = new Date();
console.log('Today:', today); // e.g., Today: Tue Jun 16 2026 10:30:00 GMT-0500 (Central Daylight Time)

// Format the current date
const formattedDate = format(today, 'yyyy-MM-dd HH:mm:ss');
console.log('Formatted date:', formattedDate); // e.g., Formatted date: 2026-06-16 10:30:00

// Add 5 days to the current date
const fiveDaysLater = addDays(today, 5);
const formattedFiveDaysLater = format(fiveDaysLater, 'MM/dd/yyyy');
console.log('Five days later:', formattedFiveDaysLater); // e.g., Five days later: 06/21/2026

// Example with a specific date
const specificDate = new Date(2025, 0, 1); // January 1, 2025
const yearAndMonth = format(specificDate, 'MMMM yyyy');
console.log('Specific date formatted:', yearAndMonth); // Specific date formatted: January 2025

This snippet demonstrates basic formatting and date arithmetic. For more advanced operations, consult the official date-fns documentation, which provides detailed examples and API references for all available functions.