UEA-PRODEM

node_modules/@date-fns/tz/tzOffset/index.js

@@ -2,30 +2,42 @@ const offsetFormatCache = {};
 const offsetCache = {};
 
 /**
- * The function extracts UTC offset in minutes from the given date in specified
+ * The function returns UTC offset in minutes for the given date in specified
  * time zone.
  *
  * Unlike `Date.prototype.getTimezoneOffset`, this function returns the value
  * mirrored to the sign of the offset in the time zone. For Asia/Singapore
- * (UTC+8), `tzOffset` returns 480, while `getTimezoneOffset` returns -480.
+ * (UTC+8), `tzOffset` returns `480`, while `getTimezoneOffset` returns `-480`.
  *
- * @param timeZone - Time zone name (IANA or UTC offset)
- * @param date - Date to check the offset for
+ * It uses `Intl.DateTimeFormat` internally to access otherwise unavailable
+ * runtime's time zone data, and falls back to basic manual parsing if Intl API
+ * is not supported (e.g., older Node.js versions, React Native's Hermes, etc.).
  *
- * @returns UTC offset in minutes
+ * @param timeZone - Time zone name (IANA or UTC offset).
+ * @param date - Date to check the offset for.
+ *
+ * @returns UTC offset in minutes (e.g., `480` for date in UTC+8).
  */
 export function tzOffset(timeZone, date) {
   try {
+    // Create `Intl.DateTimeFormat` with `"longOffset"` that gives us consistent
+    // date strings like `"5/19/2026, GMT-08:00"`.
     const format = offsetFormatCache[timeZone] ||= new Intl.DateTimeFormat("en-US", {
       timeZone,
       timeZoneName: "longOffset"
     }).format;
+
+    // Get `"-08:00"`.
     const offsetStr = format(date).split("GMT")[1];
+
+    // Avoid parsing the same offset string.
     if (offsetStr in offsetCache) return offsetCache[offsetStr];
+
+    // Calculate offset from `["-08", "00"]` and cache it.
     return calcOffset(offsetStr, offsetStr.split(":"));
   } catch {
-    // Fallback to manual parsing if the runtime doesn't support ±HH:MM/±HHMM/±HH
-    // See: https://github.com/nodejs/node/issues/53419
+    // Fallback to manual parsing if the runtime doesn't support
+    // `±HH:MM/±HHMM/±HH`. See: https://github.com/nodejs/node/issues/53419.
     if (timeZone in offsetCache) return offsetCache[timeZone];
     const captures = timeZone?.match(offsetRe);
     if (captures) return calcOffset(timeZone, captures.slice(1));