Function isZone

isZone(value: unknown): value is Zone<true>

Type guard to check if a value is a valid Luxon Zone instance.

Note that this includes the UnsetZone sentinel value.

Checks both instanceof Zone and constructor name to handle cross-module Zone instances that may not pass instanceof checks.

Parameters

value: unknown
Value to check

Returns value is Zone<true>

true if the value is a Zone instance (type guard)

Example

import { Info } from "luxon"

const zone = Info.normalizeZone("UTC+8")
if (isZone(zone)) {
  // TypeScript knows zone is Zone (not unknown)
  console.log(zone.offset(Date.now()))
}

isZone(Info.normalizeZone("UTC"))  // true
isZone("UTC")                      // false
isZone(480)                        // false
isZone(null)                       // false