Small Deno sample of downloading a binary file into a data URL

fetch-to-dataurl.ts

import * as Base64 from 'https://deno.land/[email protected]/encoding/base64.ts';

async function toDataUrl(resp: Response): Promise<string> {
  const contentType = resp.headers.get('content-type') ?? 'application/octet-stream';
  const buffer = await resp.arrayBuffer();
  return `data:${contentType};base64,`+Base64.encode(buffer);
}

const gifUrl = 'https://matthews.sites.wfu.edu/misc/jpg_vs_gif/testImage.gif';
console.log(await fetch(gifUrl).then(toDataUrl));

To address the mix of await and then:

// wait for the result of fetching this URL and then building a data URL
await fetch(gifUrl).then(toDataUrl);

// vs

// wait for the result of building a data URL out of the waited-for result of fetching this URL
await toDataUrl(await fetch(gifUrl));

Just a personal preference