Function getTimezoneGMT

src/time/localized-time.ts:196–218

(date: Date, timezone?: string)

}

function getTimezoneGMT(date: Date, timezone?: string) {
  const fmt = getOffsetFormatter(timezone);
  const parts = fmt.formatToParts(date);
  const tzPart = parts.find(p => p.type === 'timeZoneName');
  if (!tzPart) return 'Z';

  const tzValue = tzPart.value; // e.g. "GMT-5", "GMT+5:30", "GMT"
  if (tzValue === 'GMT') return 'Z';

  // Parse the offset from the Intl-provided string
  const match = tzValue.match(/^GMT([+-])(\d{1,2})(?::(\d{2}))?$/);
  if (!match) return 'Z';

  const sign = match[1];
  const hoursNum = parseInt(match[2]);
  const minutesNum = parseInt(match[3] || '0');
  if (hoursNum === 0 && minutesNum === 0) return 'Z';

  const hours = match[2].padStart(2, '0');
  const minutes = (match[3] || '00').padStart(2, '0');

  return `GMT${sign}${hours}:${minutes}`;
}