hasDaylightSaving

Signature

hasDaylightSaving(timeZone: string): boolean

import { hasDaylightSaving } from "@northguild/gmt/zoned/validate";

Check whether an IANA timeZone identifier observes daylight saving time.

• Compares UTC offsets at two dates six months apart (January and July).
• A zone is considered to have DST if its offset differs between the two dates.
• Returns false for invalid or unresolvable timeZone identifiers.

Parameters

Parameter	Type	Description
timeZone	string	timeZone identifier to check

Returns

boolean indicating whether the timeZone observes DST

Examples

hasDaylightSaving("America/New_York") // true
hasDaylightSaving("Europe/Berlin") // true
hasDaylightSaving("Asia/Tokyo") // false
hasDaylightSaving("UTC") // false
hasDaylightSaving("Invalid/Zone") // false

Source

zoned/validate/hasDaylightSaving.ts