!Add to Calendar Time Zone iCal Library


Add to Calendar Time Zones iCal Library

Convert the IANA (formerly Olson) time zone database files into VTIMEZONE blocks, compatible with the iCalendar specification (RFC2445).

It is based on vzic, but only provides the VTIMEZONE part to easily put this into any other iCal generator (like the add-to-calendar-button).
It is built to be used standalone, via API, or as JavaScript/TypeScript module, hosted as npm package.

---

📦 Installation / Setup

$3

$3

`
npm install timezones-ical-library
`

$3

For CommonJS:

`
require tzLib = require('timezones-ical-library');
`

With ES:

`
import { tzlib_get_ical_block, tzlib_get_offset, tzlib_get_timezones } from 'timezones-ical-library';
`

$3

#### A. Get time zones

Use tzlib_get_timezones() to retrieve a list of all available time zone strings.
You can pass true to retrieve a JSON formatted string instead of an array.
For CommonJS, you would use tzLib.tzlib_get_timezones().

#### B. Get the iCal time zone block

Use the tzlib_get_ical_block(tzName) function to return the proper iCal VTIMEZONE block for a given time zone string (tzName).
Again, pass true to retrieve a JSON formatted string instead of an array _(not recommended)_.
For CommonJS, you would use tzLib.tzlib_get_ical_block(tzName).

You will receive an array, holding the VTIMEZONE block first, and the TZID line (additionally) second. The latter one is needed for any further time statement.

Include this into your iCal data to come up with a complete ics file.

A final constellation could look like this:

`diff
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-// github.com/add2cal/add-to-calendar-button //EN
CALSCALE:GREGORIAN
+ BEGIN:VTIMEZONE
+ TZID:America/New_York
+ LAST-MODIFIED:20220824T133813Z
+ X-LIC-LOCATION:America/New_York
+ BEGIN:DAYLIGHT
+ TZNAME:EDT
+ TZOFFSETFROM:-0500
+ TZOFFSETTO:-0400
+ DTSTART:19700308T020000
+ RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
+ END:DAYLIGHT
+ BEGIN:STANDARD
+ ZNAME:EST
+ TZOFFSETFROM:-0400
+ TZOFFSETTO:-0500
+ DTSTART:19701101T020000
+ RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
+ END:STANDARD
+ END:VTIMEZONE
BEGIN:VEVENT
UID:2022-08-30T19:29:38.618Z@add-to-calendar-button
DTSTAMP:20230214T091500Z
DTSTART;TZID=America/New_York:20230214T091500
DTEND;TZID=America/New_York:20230218T223000
SUMMARY:A sample event
DESCRIPTION:Just some descriptive text...
LOCATION:World Wide Web
STATUS:CONFIRMED
LAST-MODIFIED:20220830T192938Z
SEQUENCE:0
END:VEVENT
END:VCALENDAR
`

#### C. Get a specific offset

Use tzlib_get_offset(tzName, isoDate, isoTime) to get specific offset (relative to UTC), based on a provided date and time.

For example, you can provide _tzName_ 'Europe/Berlin', _isoDate_ '2023-05-23', and _isoTime_ '15:45' in order to retrieve the offset, which applies for this time zone at the 23rd of May in 2023 at exactly 15:45.

---

⚙️ API

Instead of using this code or the npm package, you could also make use of the free and open API.

$3

`
https://tz.add-to-calendar-technology.com/api/zones.json
`

$3

`
https://tz.add-to-calendar-technology.com/api/{{zoneName}}.ics
`

With {{zoneName}}` being your time zone.
So, for New York, this would be https://tz.add-to-calendar-technology.com/api/America/New_York.ics.

This is case sensitive!

> [!WARNING]
> Mind that this does not deliver a fully valid ics file, since it only contains the VTIMEZONE part. You will need to combine this with your other event information.

---

🙌 Contributing

Anyone is welcome to contribute, but mind the guidelines:

- Bug reports
- Feature requests
- Pull requests

📃 Copyright and License

Copyright (c) Jens Kuerschner. Licensed under Apache-2.0.

⚡ Changelog

!npm version

💜 Kudos go to

- The "Time Zone King" Paul Eggert for optimizing time zones for the web, ...
- as well as all the contributors at the official tz repository.
- The awesome authors of zic, vzic, and libical; mainly Damon Chaplin, Allen Winter, and Ken Murchison.