image.ts

gistfile1.txt

function image(url: string): Promise<Buffer | undefined> {
  return fetch(url).then(
    res => {
      if (res.status !== 200) {
        return undefined;
      }

      return res.buffer();
    },
    () => {
      return undefined;
    },
  );
}

function images(urls: string[]): Promise<Buffer[]> {
  return Promise.all(urls.map(url => image(url))).then(buffers =>
    buffers.filter((buffer): buffer is Buffer => !!buffer),
  );
}