chore: import upstream snapshot with attribution

2026-07-13 13:32:57 +08:00
commit cd420f9332
4811 changed files with 884702 additions and 0 deletions
@@ -0,0 +1,22 @@
+export function getTimezones(includeUtc = true) {
+  const possibleTimezones = Intl.supportedValuesOf("timeZone").sort();
+  if (includeUtc) {
+    possibleTimezones.unshift("UTC");
+  }
+  return possibleTimezones;
+}
+
+/**
+ * Whether the runtime can resolve this IANA timezone. Prefer this over checking membership
+ * in `Intl.supportedValuesOf("timeZone")`, which lists only canonical ids and omits zones
+ * browsers legitimately report (e.g. "UTC", "Etc/UTC", "Asia/Kolkata") — rejecting those
+ * would leave a client's stored timezone stale.
+ */
+export function isValidTimeZone(timeZone: string): boolean {
+  try {
+    new Intl.DateTimeFormat("en-US", { timeZone });
+    return true;
+  } catch {
+    return false;
+  }
+}