fix: unknown tz (#34)

* chore: add comment and type * fix: This code ensures that if tz is undefined, the toLowerCase function is not called.
formkit · Mar 7, 2024 · 0245e40 · 0245e40
1 parent 980428e
commit 0245e40
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Showing 2 changed files with 4 additions and 2 deletions.
diff --git a/src/deviceTZ.ts b/src/deviceTZ.ts
@@ -1,6 +1,8 @@
 /**
  * Get the timezone of the device.
+ *
+ * * Note: If the environment variable TZ is not set, it will return undefined.
  */
-export function deviceTZ() {
+export function deviceTZ(): string | undefined {
   return Intl.DateTimeFormat().resolvedOptions().timeZone
 }
diff --git a/src/format.ts b/src/format.ts
@@ -77,7 +77,7 @@ export function format(
 
   // We need to apply an offset to the date so that it can be formatted as UTC.
   tz ??= deviceTZ()
-  if (tz.toLowerCase() !== "utc") {
+  if (tz?.toLowerCase() !== "utc") {
     inputDateOrOptions = removeOffset(
       inputDateOrOptions,
       offset(inputDateOrOptions, tz, "utc")