A lightweight, zero-dependency library to determine possible IANA timezones by comparing local time and UTC time.
npm install possible-tzA lightweight, zero-dependency library to determine possible IANA timezones by comparing local time and UTC time.
This library helps you identify which timezones a user might be in when you know their local time and the corresponding UTC time. This is particularly useful for systems that need to automatically detect a user's timezone without relying on geolocation, using only system clock information.
- High Accuracy: Determines timezones by comparing specific moments in time.
- DST Support: Naturally handles Daylight Saving Time transitions.
- Comprehensive: Supports non-standard offsets (e.g., India UTC+5:30 or Nepal UTC+5:45).
- High Performance: Caches formatters for efficient repeated lookups.
- Lightweight: Zero external dependencies, leveraging the built-in Intl.DateTimeFormat API.
``bash`
npm install possible-tz
`typescript
import { getPossibleTimezones, CheckingDateTime, UtcDateTime } from 'possible-tz';
// Example for Tokyo (UTC+9)
// January 1, 2024, 18:00:00 local time
const local = new CheckingDateTime(2024, 0, 1, 18, 0, 0);
// At the same moment, it was 09:00:00 UTC
const utc = new UtcDateTime(2024, 0, 1, 9, 0, 0);
// Get the list of matching timezones
const timezones = getPossibleTimezones(local, utc);
console.log(timezones);
// Output: ['Asia/Chita', 'Asia/Tokyo', 'Pacific/Palau', ...]
`
The main function that takes two time objects and returns an array of IANA timezone strings.
- Parameters:
- local: CheckingDateTime - The local time to check.utc
- : UtcDateTime - The reference UTC time.string[]
- Returns: - Array of matching IANA timezone identifiers.
A class representing the local time components.
Constructor: (year, month, date, hours, minutes, seconds?)
- is 0-indexed (0 = January).seconds
- defaults to 0.
A class representing the UTC reference time components.
Constructor: (year, month, date, hours, minutes, seconds?)
- is 0-indexed (0 = January).seconds` defaults to 0.
-
MIT