File System API Permission Check

Check and request permissions for browser File System API.

Returns true immediately if current permission is granted. Requests permission if not granted. Permission request must be called within a user click event.

async function verifyPermission(handle: FileSystemHandle, readWrite: boolean) {
  const options = {};
  if (readWrite) {
    options.mode = 'readwrite';
  }

  // 1. Check current permission
  if ((await handle.queryPermission(options)) === 'granted') {
    return true;
  }

  // 2. Request permission if not granted
  if ((await handle.requestPermission(options)) === 'granted') {
    return true;
  }

  return false;
}