Introducing Minitz - Time zone conversion in JavaScript

by Hexagon, 2 minutes read javascript time-zones conversion tz library

Minitz is a minimal utility that allows you to convert to or from any timezone. It is compatible with Deno, Node, and browsers, and is less than 2KB when minified. The library is MIT-licensed, which means you can use it any way you want.

Why I wrote Minitz

Converting a Date object to another timezone in JavaScript is possible using the Intl feature of vanilla JS.

// Get current time in Asia/Tokyo, using vanilla js
new Date().toLocaleString("sv-SE", { timeZone: "Asia/Tokyo" });
// -> 2022-09-15 17:23:45

However, I needed a simple and lightweight utility for croner that could convert dates between different timezones in JavaScript, both to and from. I found that existing libraries were either too complex, too heavy for my needs or didn't support module imports.

Minitz is the solution to these problems. Let's see some examples on converting from a time zone:

// Get local time from time in Asia/Tokyo, using minitz and vanilla js
const localTime = minitz(2022, 9, 15, 23, 0, 0, "Asia/Tokyo");
// -> 2022-09-15 16:00:00

And converting between time zones:

// Get time in America/New_York from time in Asia/Tokyo, using minitz and vanilla js
// Also demonstrates that it's possible to use ISO8601 strings as input to minitz, through `.fromTZISO`
const localTime = minitz.fromTZISO("2022-09-15 23:00:00", "Asia/Tokyo");
  localTime.toLocaleString("sv-SE", { timeZone: "America/New_York" }),
// -> 2022-09-15 10:00:00

How does it work?

Minitz works by relying on the built-in JavaScript Intl API to perform timezone conversions. It uses current best practices and is designed to work in all environments, including Node, Deno, and browsers. Minitz is compatible with ESM, UMD, and CommonJS.

For those interested in the details, the code in these lines within the GitHub repository works its magic.

Using minitz

Minitz can be installed through NPM, or imported from The source code is available at

Once you have installed or imported Minitz, you can use it to convert dates between different timezones in JavaScript using the examples above.

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