Function loadZone

packages/zone.js/lib/zone.ts:70–89

()

}

export function loadZone(): ZoneType {
  // if global['Zone'] already exists (maybe zone.js was already loaded or
  // some other lib also registered a global object named Zone), we may need
  // to throw an error, but sometimes user may not want this error.
  // For example,
  // we have two web pages, page1 includes zone.js, page2 doesn't.
  // and the 1st time user load page1 and page2, everything work fine,
  // but when user load page2 again, error occurs because global['Zone'] already exists.
  // so we add a flag to let user choose whether to throw this error or not.
  // By default, if existing Zone is from zone.js, we will not throw the error.
  const global = globalThis as any;
  const checkDuplicate = global[__symbol__('forceDuplicateZoneCheck')] === true;
  if (global['Zone'] && (checkDuplicate || typeof global['Zone'].__symbol__ !== 'function')) {
    throw new Error('Zone already loaded.');
  }

  // Initialize global `Zone` constant.
  global['Zone'] ??= initZone();
  return global['Zone'];
}