Support async onDataChange about react-fetch-component HOT 1 CLOSED

<Fetch
  url="https://httpbin.org/image/jpeg"
  as={res => {
    return res.blob()
      .then(blob => new Promise((resolve, reject) => {
        const reader = new FileReader();
        reader.onload = e => resolve(e.target.result);
        reader.readAsDataURL(blob);
      }));
  }}
  manual
>
  {({ data: dataUrl, fetch }) => (
    dataUrl ? (
      <img src={dataUrl} />
    ) : (
        <button onClick={() => fetch()}>Download</button>
      )
  )}
</Fetch>

<Fetch
  url="https://httpbin.org/image/jpeg"
  as={res => res.blob().then(blob => URL.createObjectURL(blob))}
  manual
>
  {({ data: dataUrl, fetch }) =>
    dataUrl ? (
      <img src={dataUrl} />
    ) : (
      <button onClick={() => fetch()}>ObjectURL</button>
    )
  }
</Fetch>