jstimezonedetect
This script gives you the zone info key representing your device's time zone setting. The return value is an IANA zone info key (aka the Olson time zone database).
date-fns-timezone
Parsing and formatting date strings using IANA time zones for date-fns.
date-fns-tz
Time zone support for date-fns v3 with the Intl API
timezone-support
Lightweight time zone support for your applications or other date libraries.