Provide an equivalent of require.main for ESM

[mcollina]

Currently there is no equivalent of require.main for ESM scripts.
Note that this is not listed at all in https://nodejs.org/api/esm.html#differences-between-es-modules-and-commonjs either.

The "known" equivalent would be to use process.argv[1] === new URL(import.meta.url).pathname), but it doesn't work with symbolic links (e.g. npm bin scripts).

A solution is to use https://www.npmjs.com/package/es-main, which practically goes down to require to implement it. I think we should really include something out of the box.

[mcollina]

cc @marco-ippolito @GeoffreyBooth I think we should add this to the "ESM parity" initiative.

[marco-ippolito]

For reference #49440

wintercg/import-meta-registry#4

[mcollina]

I don't think we should wait for wintercg, but rather add a getter in process or something in util.

[ljharb]

Since it's per-module, it'd have to either live on import.meta or take import.meta.url as an argument.

[GeoffreyBooth]

#49440 has pretty much all the context. I think someone could read that full thread and just go ahead and build it at this point; there are some points around how to treat worker entry points that might still need working out, but those finer details could happen within the PR. (@mcollina you know a lot about worker threads, if you want to tackle this 😉.)

Ideally our implementation would be compatible/interoperable with Deno’s. See https://github.com/wintercg/import-meta-registry#:~:text=webappapis.html%23hostgetimportmetaproperties-,import.meta.main,-Returns%20whether%20the and https://docs.deno.com/runtime/reference/deno_namespace_apis/#importmeta--api:~:text=com/main.ts-,import.meta.main,-Returns%20whether%20the

[joyeecheung]

Another duplicate #57226

[mcollina]

Closing then.