use set to cache repeat solutions

JavaScript
/**
 * @description Get file tree by a mtp device parent path.
 * @param parentPath  The root address can be passed in the string `/`.
 * @returns `Array<FileInfo>` File info array
 * @example
 *
 *        [{
 *            name: '1',
 *            size: 0,
 *            type: 'FOLDER',
 *            id: 156,
 *            modificationdate: 1672041505,
 *            parent_id: 152,
 *            storage_id: 65537
 *        },
 *        {
 *            name: 'download.zip',
 *            size: 8893742,
 *            type: 'FILE',
 *            id: 158,
 *            modificationdate: 1673321627,
 *            parent_id: 152,
 *            storage_id: 65537
 *        }]
 *
 */
// getList(parentPath: string): Array<FileInfo>;

export async function getImages(parentPath, visitedFolders = new Set()) {
  if (visitedFolders.has(parentPath)) {
    return [];
  }
  visitedFolders.add(parentPath);
  const fileLists = await this.getFileList(parentPath);
  const imageExtensions = /\.(jpg|png|gif|webp|jpeg)$/i;
  let images = [];
  const promises = [];
  fileLists.forEach((target) => {
    if (target.type === "FOLDER") {
      const currentPath = parentPath + "/" + target.name;
      promises.push(this.getImages(currentPath, visitedFolders));
    } else if (target.type === "FILE" && imageExtensions.test(target.name)) {
      images.push(target);
    }
  });
  const results = await Promise.all(promises);
  results.forEach((result) => {
    images = images.concat(result);
  });
  return images;
}