Honor Nodejs environment variables

[turran]

Be able to pass Node.js environment variables through the command line and make them available to Emscripten

[kleisauke]

This is a breaking change, see e.g. the discussion in PR #18820.

[turran]

Thanks @kleisauke I wasn't aware of that PR.
I don't understand why such a change can be a breaking change. Not honoring node env is a missing feature as there is no way to pass environment variables other than manually modifying the .js file, which is impractical from the user PoV.

[sbc100]

Thanks @kleisauke I wasn't aware of that PR. I don't understand why such a change can be a breaking change. Not honoring node env is a missing feature as there is no way to pass environment variables other than manually modifying the .js file, which is impractical from the user PoV.

Its a little more subtle than that. Emscripten tends to present a kind of virtual environment. By default for example, we don't expose the user's actual filesystem, even under node. You have to opt into that behaviour. See https://github.com/emscripten-core/emscripten/pull/18820/files#r1114735936

I do think we want to enable this behaviour somehow, but it will likely need to be behind some kind of flag.

In any case this does appear to be a duplicate of #18820, no?