date-and-time

date-and-time

The simplest, most intuitive date and time library.

Installation

npm install date-and-time

ES Modules (Recommended)

import { format } from 'date-and-time';

format(new Date(), 'ddd, MMM DD YYYY');
// => Wed, Jul 09 2025

CommonJS

const { format } = require('date-and-time');

format(new Date(), 'ddd, MMM DD YYYY');
// => Wed, Jul 09 2025

CDN Usage

Via jsDelivr

<script type="module">
  import { format } from 'https://cdn.jsdelivr.net/npm/date-and-time/dist/index.js';

  console.log(format(new Date(), 'YYYY/MM/DD'));
</script>

Via unpkg

<script type="module">
  import { format } from 'https://unpkg.com/date-and-time/dist/index.js';

  console.log(format(new Date(), 'YYYY/MM/DD'));
</script>

Migration

Version 4.x has been completely rewritten in TypeScript and some features from 3.x are no longer compatible. The main changes are as follows:

• The timezone and timespan plugins have been integrated into the main library
• Tree shaking is now supported
• Supports ES2021 and no longer supports older browsers

For details, please refer to migration.md. If you use an AI coding agent, the date-and-time-migration skill can carry out the migration; see Agent Skills.

API

For comprehensive documentation and examples, visit: GitHub Pages

Agent Skills

This repository ships two Agent Skills that help AI coding agents (Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, and others) work with this library:

Skill	Use it to
date-and-time	Write code with date-and-time v4: formatting, parsing, timezones, locales, plugins, date arithmetic, durations
date-and-time-migration	Migrate a project from date-and-time v3 to v4

Each skill is self-contained, so you can install either one on its own. The skills are not part of the npm package.

Install

With the skills CLI:

# Both skills, into the current project
npx skills add knowledgecode/date-and-time --skill date-and-time --skill date-and-time-migration

# One skill, globally, for a specific agent (Claude Code here)
npx skills add knowledgecode/date-and-time --skill date-and-time -g -a claude-code

# See what the repository offers before installing
npx skills add knowledgecode/date-and-time --list

Or copy a skill directory by hand into your agent's skills directory (.claude/skills/ for Claude Code, .agents/skills/ for agents that follow the shared convention):

git clone --depth 1 https://github.com/knowledgecode/date-and-time.git
mkdir -p .claude/skills
cp -R date-and-time/skills/date-and-time .claude/skills/

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.