Introduction

Datezone is a lightweight, high-performance date and timezone utility library for JavaScript and TypeScript. It provides a simple, modern API for parsing, formatting, comparing, and working with dates and times. Every function includes full support for IANA timezones and DST.

import { startOfDay, toISOString } from "datezone";

const now = startOfDay(Date.now(), "Asia/Singapore");

console.log(toISOString(now, "America/New_York"));

🎯 Why Datezone

Because Date & Time in JavaScript is really hard!

JavaScript's native Date object has no timezone support. Existing libraries need extra plugins like @date-fns/tz or date-fns-tz that add complexity with wrapper objects like TZDate.

Datezone is built from the ground up with timezones and DST support built into every function. No plugins or special wrapper objects needed.

🏗️ Modern Architecture

• Built on the modern Intl API and math calculations instead of relying on the Date object
• Performance first - uses timestamps to be memory efficient
• Made to run 1000 times a second without performance loss
• Easier to send over HTTP with timestamp-based operations

🚀 Blazing Fast Performance

• 18,000%+ faster in timezone operations
• 45,000%+ faster for simple date math
• No performance loss as your app scales

See Comparison and Benchmarks

📦 Developer Experience

• ESM only tree-shaking - only import what you use
• 100% TypeScript with strict types that catch errors at compile time
• Zero dependencies - no extra packages to worry about
• 33.76KB total size, competitive with major alternatives

🌍 Native Timezone Excellence

• Timezones built into every function - no plugins required
• Native IANA timezone support with automatic DST handling

import { addDays, calendarToTimestamp, format, type TimeZone } from "datezone";

// 💡 Instead of using browser timeZone,
// store users preferred timeZone in session storage or database.
const timeZone: TimeZone = "America/New_York";
const locale = "en-US";

// Convert a calendar date to timestamp
const date = calendarToTimestamp(2024, 6, 1, 0, 0, 0, 0, timeZone);

// Add 5 calendar days in New York Timezone
const future = addDays(date, 5, timeZone);

// Format the date in New York Timezone with the user's locale
const result = format(future, "yyyy-MM-dd HH:mm:ss", {
	locale,
	timeZone,
});

console.log(result); // 2024-06-06 00:00:00

// Or if you want to format in Different Timezone
const tokioResult = format(future, "yyyy-MM-dd HH:mm:ss", {
	locale,
	timeZone: "Asia/Tokyo",
});

console.log("Same date & time in Tokyo:", tokioResult); // 2024-06-06 13:00:00

Get Started

Check out the Installation or take a deep dive into how DST Transition works.