Stream a file as an HTTP Response

Bun.file() accepts a path and returns a lazily-loaded BunFile instance, which you can pass directly to the new Response constructor.

server.ts

const path = "/path/to/file.txt";
const file = Bun.file(path);
const resp = new Response(file);

Bun determines the Content-Type from the file extension and sets it on the Response.

server.ts

new Response(Bun.file("./package.json")).headers.get("Content-Type");
// => application/json;charset=utf-8

new Response(Bun.file("./test.txt")).headers.get("Content-Type");
// => text/plain;charset=utf-8

new Response(Bun.file("./index.tsx")).headers.get("Content-Type");
// => text/javascript;charset=utf-8

new Response(Bun.file("./img.png")).headers.get("Content-Type");
// => image/png

Putting it all together with Bun.serve().

server.ts

// static file server
Bun.serve({
  async fetch(req) {
    const path = new URL(req.url).pathname;
    const file = Bun.file(path);
    return new Response(file);
  },
});

See Bun.write().