Node.js recursively grab all files in folder

getFiles.ts

function getFiles(dir: string, fileList?: []) {
  let files = fs.readdirSync(dir);
  fileList = fileList || [];
  files.forEach(async (file) => {
    if(fs.statSync(dir + file).isDirectory()) {
      // @ts-ignore
      fileList = await getFiles(dir + file + '/', fileList);
    } else {
      // @ts-ignore
      fileList.push( dir + '/' + file);
      console.log('Found file at: ', dir + file);
    }
  });

  return new Promise((resolve) => resolve(fileList));
}