// 10個の文字列配列を生成する。
const array = [...Array<string>(10)].map(() => {
    return 'dummy string'
})

// 3秒待つ
await new Promise(resolve => setTimeout(resolve, 3000));

    return new Promise(resolve => {
      (async () => {
        // 3秒待つ
        await new Promise(resolve => setTimeout(resolve, 3000));

        resolve();
      })();
    });