🐛 BUG: Support __dirname

[noClaps]

Describe the solution

I'm pretty sure this is a bug, but I didn't see a bug report issue so I opened a feature request instead.

I'm getting this error:

Uncaught ReferenceError: __dirname is not defined

Minimal reproduction:

// index.ts
import { Hono } from "hono";

const app = new Hono();

console.log(__dirname);

export default app 

and my wrangler.toml:

main = "index.ts"
compatibility_date = "2024-12-22"
compatibility_flags = ["nodejs_compat"]

Expected behavior

__dirname should output the directory that the file is currently in, similar to import.meta.dir.

[emily-shen]

Hi, as dirname doesn't really make sense for us to implement as Workers are serverless functions without a filesystem. It should be mocked with nodejs_compat though, so if you're using a library that has __dirname somewhere, but you're not actually relying on that actually outputting a directory name, that should still work (not sure if your repro has been simplified just for demo purposes).

[noClaps]

The demo was simplified, I was actually using a library that uses __dirname, but it wasn't being mocked with nodejs_compat, hence why I opened the issue. My guess is that because the files get bundled into one single JS file before running, __dirname gets included in that, and it refuses to run.

[emily-shen]

Ah I see, that makes more sense 😅

cc @vicb