provideBlob: Return Response Quickly and Poll for the Expensive Parts

See @postpostscript/provideBlobExample for full example. You will need to fork this val to use provideBlob on your projects as it uses @std/blob for storage

Create val
import { Image } from "https://deno.land/x/imagescript@1.2.17/mod.ts";
import { htmlResponse } from "https://esm.town/v/postpostscript/html";
import { provideBlob } from "https://esm.town/v/postpostscript/provideBlob";

export default async function(req: Request) {
  const image = provideBlob(async () => {
    const png = new Image(100, 100);
    png.drawCircle(50, 50, 50, 100);
    return png.encode();
  }).jsPromise();

  return htmlResponse`
    <div id="image"></div>

    <script>
      ${image}.then(blob => {
        const $img = document.createElement("img")
        $img.src = URL.createObjectURL(blob)
        document.getElementById("image").appendChild($img)
      })
    </script>
  `;
}

Migrated from folder: HTML/provideBlob