date-fns

name	date-fns
description	Modern JavaScript date utility library with modular, tree-shakeable functions for formatting, parsing, comparison, and manipulation
layer	domain
category	utility
triggers	["date-fns","date formatting","date parsing","date comparison","date manipulation","formatDistance","parseISO"]
inputs	["Date formatting or display requirements","Date arithmetic or comparison logic","Timezone handling needs"]
outputs	["Tree-shakeable date utility implementations","Locale-aware date formatting","Timezone-safe date operations"]
linksTo	["typescript-frontend","react","nodejs"]
linkedFrom	["forms","i18n"]
riskLevel	low
memoryReadPolicy	none
memoryWritePolicy	none
sideEffects	[]

date-fns

Overview

Modern JavaScript date utility library. Each function is a standalone module — import only what you use for minimal bundle size. Works with native Date objects (no wrapper types).

When to Use

• Formatting dates for display (relative time, localized strings, durations)
• Parsing date strings from APIs or user input
• Comparing or sorting dates, checking ranges
• Date arithmetic (add/subtract days, find start/end of periods)
• Timezone conversions (via date-fns-tz)

Key Patterns

Formatting

import { format, formatDistance, formatRelative, formatDuration, intervalToDuration } from 'date-fns';

format(new Date(), 'yyyy-MM-dd HH:mm');           // "2026-03-10 14:30"
formatDistance(subDays(new Date(), 3), new Date()); // "3 days ago" (with { addSuffix: true })
formatRelative(subDays(new Date(), 1), new Date()); // "yesterday at 2:30 PM"
formatDuration(intervalToDuration({ start: 0, end: 90000000 })); // "1 day 1 hour"

Parsing

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

parseISO();                   
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