Time-Since

A robust, type-safe utility for calculating and formatting time differences. timeSince provides a flexible solution for determining elapsed time with support for multiple output formats, internationalization, and precise handling of edge cases like future dates and timezone differences.

Features

• Type-Safe: Written in TypeScript with full type definitions
• Multiple Output Formats: Return elapsed time as:
  • Complete breakdown object with years, months, days, etc.
  • Single unit values (milliseconds, seconds, days, etc.)
  • Human-readable relative strings ("2 days ago", "last year", etc.)
• Internationalization Support: Format relative times in any locale
• Edge Case Handling:
  • Future dates with correct time until representation
  • Accurate leap year calculations
  • Proper timezone handling
  • Zero time difference ("now")
• Zero Dependencies: Lightweight with no external dependencies
• 100% Test Coverage: Comprehensive test suite ensures reliability

Installation

Using npm

npm install @risadams/time-since

Using yarn

yarn add @risadams/time-since

Using pnpm

pnpm add @risadams/time-since

Usage

The library supports both ESM and CommonJS imports.

ESM Import

import { timeSince } from '@risadams/time-since';

CommonJS Import

const { timeSince } = require('@risadams/time-since');

TypeScript

The package includes TypeScript type declarations:

import { timeSince } from '@risadams/time-since';
// Types are automatically available

Examples

Basic Usage (Default Object Output)

import { timeSince } from '@risadams/time-since';

// As of May 1, 2025
const result = timeSince('2020-01-01');
console.log(result);
/* Output:
{
  date: Date("2020-01-01T00:00:00.000Z"),
  asOf: Date("2025-05-01T00:00:00.000Z"),
  years: 5,
  months: 4,
  days: 0,
  hours: 0,
  minutes: 0,
  seconds: 0,
  milliseconds: 0
}
*/

Specific Time Unit Formats

// Get total milliseconds elapsed
const ms = timeSince('2025-04-30', { format: 'milliseconds' });
console.log(ms); // Output: 86400000 (1 day in milliseconds)

// Get total days elapsed
const days = timeSince('2025-04-01', { format: 'days' });
console.log(days); // Output: 30 (30 days)

// Get total months elapsed
const months = timeSince('2024-05-01', { format: 'months' });
console.log(months); // Output: 12 (12 months)

// Get total years elapsed
const years = timeSince('2020-05-01', { format: 'years' });
console.log(years); // Output: 5 (5 years)

Human-Readable Relative Time

// Default locale (English)
const relative = timeSince('2025-04-30', { format: 'relative' });
console.log(relative); // Output: "yesterday"

// Different locales
const french = timeSince('2024-05-01', { format: 'relative', locale: 'fr' });
console.log(french); // Output: "il y a 1 an" (1 year ago)

const spanish = timeSince('2025-04-29', { format: 'relative', locale: 'es' });
console.log(spanish); // Output: "hace 2 días" (2 days ago)

const german = timeSince('2025-03-01', { format: 'relative', locale: 'de' });
console.log(german); // Output: "vor 2 Monaten" (2 months ago)

Working with Future Dates

// Future date (June 1, 2025 - 1 month in the future from May 1, 2025)
const futureResult = timeSince('2025-06-01');
console.log(futureResult.months); // Output: 1 (1 month until this date)

// Relative format automatically handles future dates
const futureRelative = timeSince('2025-06-01', { format: 'relative' });
console.log(futureRelative); // Output: "in 1 month"

Working with Different Date Formats

// ISO format
const isoDate = timeSince('2025-04-01T12:00:00Z');

// Short date format
const shortDate = timeSince('4/1/2025');

// Long date format
const longDate = timeSince('April 1, 2025');

// Unix timestamp
const timestamp = timeSince(new Date('2025-04-01').getTime());

// Date object
const dateObj = timeSince(new Date('2025-04-01'));

API Reference

timeSince(date, options?)

Parameters

• date (Date | string): The starting date from which to calculate elapsed time
• options (Object, optional): Configuration options
  • format (string, optional): Output format
    • 'object' (default): Returns a detailed breakdown object
    • 'milliseconds', 'seconds', 'minutes', 'hours', 'days', 'months', 'years': Returns elapsed time in the specified unit
    • 'relative': Returns a human-readable string using Intl.RelativeTimeFormat
  • locale (string, optional): BCP 47 language tag for relative formatting (default: 'en')

Returns

• With format='object': A TimeSinceResult object containing date breakdown
• With format='milliseconds', 'seconds', etc.: A number representing elapsed time in that unit
• With format='relative': A localized string representing the relative time

Running Tests

The project includes a comprehensive test suite with 100% code coverage:

# Run tests
npm test

# Run tests with coverage report
npm run test:coverage

Contribute

If you think this could be better, please open an issue!

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License

MIT © 1996+ Ris Adams