JSZip

web標準のReadableStreamは読めないようだ

code:sample.js

(async () => {

const zip = new JSZip();

const readableStream = (

await fetch("data:image/gif;base64,R0lGODdhBQAFAIACAAAAAP/eACwAAAAABQAFAAACCIwPkWerClIBADs=")

).body;

zip.file("smile.gif", readableStream);

const blob = await zip.generateAsync({ type: "blob" });

open(URL.createObjectURL(blob));

})();