Documentation or tutorial on how to use Bun.Transpiler?

[mfcochauxlaberge]

I'm building a quick little app with Bun to experiment with, and so far I find it impressive. I have experience with SPAs and backend, but almost none with SSR.

I'm trying to build an app that works both with and without JavaScript in the browser, and there's some logic handled by a backend.

I can run my frontend with bun dev and my backend with bun run server.ts. That works, but I would like to run everything under a single command instead of two processes listening on two ports.

What I've done so far is just use bun run server.ts and have the server return the frontend assets. Using Bun.Transpiler, I can convert my TS to JS and it seems to work with a simple script.

Example, using Hono:

app.get("/index.ts", async (c) => {
  let f = Bun.file("./index.ts");
  let data = await Bun.readableStreamToText(f.stream());

  let t = new Bun.Transpiler({});
  let out = t.transformSync(data, "ts");

  c.header("Content-Type", "text/javascript;charset=utf-8");

  return c.body(out);
});

But right now I am totally blocked because I cannot deal with imports.

If my script contains the following:

import Cookies from "js-cookie";

Then the JS output will be the same and the browser won't be able to deal with that.

When I use bun dev, the output looks like this:

import Cookies from "http://localhost:3000/node_modules/js-cookie/dist/js.cookie.mjs";

Which is what I would like to be able to produce programmatically from my Hono handler.

I read the docs in types.d.ts from bun-types, but couldn't figure out a way to solve my issue.

In other words, what's the best way to manually do what bun dev does in an Hono handler?

Thanks

[mfcochauxlaberge]

It seems like I'm getting closer to my goal by using esbuild directly (which Bun also uses for some cases). From what I read in the Discord server, transforming is supported (using Bun.Transpiler), but bundling isn't yet, which is what I think I need in order to make the imports.

esbuild can be used with bun run esbuild, but it lacks some APIs to be imported and use in a script (child_process and maybe more?).