build(docs): don't install NPM global deps if they're already installed

[agilgur5]

Motivation

Only install NPM global deps if they're not already installed

• previously the make commands would unconditionally install these global deps, which was unnecessary & inefficient the vast majority of the time
  • it would reinstall these every single time I ran these commands

Modifications

• use npm list -g to check if they're installed first

  • this exits with error code 1 if it doesn't exist

• note: that was the purpose of the /usr/local/bin/ part in the Makefile, but this is not universally installed in the same place

  • can run npm prefix -g and concat /bin/ to that to get the path to your global installs
    • on my Mac with versioned node (using rtx), the path is: /Users/<my-user>/.local/share/rtx/installs/node/20.6.0/bin/
    • in the devcontainer with versioned node (uses nvm), the path is: /usr/local/share/nvm/versions/node/v20.5.1/bin

Verification

1. Manually ran the commands with the dependency, confirmed it skipped the install
2. Manually ran the commands without the dependency, confirmed it performed the install

[agilgur5]

@isubasinghe this might make the USE_NIX check no longer necessary? If Nix is installing as a global dep, then this should work for it as well. If so, I can remove the checks for these deps (simplifying the Makefile a tiny bit)

[isubasinghe]

This seems sensible to me

[isubasinghe]

@agilgur5 The dependency isn't really installed in Nix via a npm install -g equivalent, so npm list -g will fail (I tested this out),
so the Makefile will have to remain as it is.

I don't think this is necessarily a negative though, it does make the Makefile more consistent at least.

[agilgur5]

@agilgur5 The dependency isn't really installed in Nix via a npm install -g equivalent, so npm list -g will fail (I tested this out)

Thanks for checking!
I thought node2nix might create a similar environment or that the Nix shell would register it an equivalent way, especially if it puts it on $PATH for the make commands to work.
But I guess not, here's the line that modifies $PATH. Potentially a limitation of node2nix or how it was configured, since for reproducibility it should behave similarly to npm i -g

[isubasinghe]

@agilgur5 The dependency isn't really installed in Nix via a npm install -g equivalent, so npm list -g will fail (I tested this out)

Thanks for checking! I thought node2nix might create a similar environment or that the Nix shell would register it an equivalent way, especially if it puts it on $PATH for the make commands to work. But I guess not, here's the line that modifies $PATH. Potentially a limitation of node2nix or how it was configured, since for reproducibility it should behave similarly to npm i -g

No worries, I don't quite know how it works but I believe it might be due to not assuming a global node installation. I think its a node2nix limitation, really I should replace that tool with raw Nix.

[agilgur5]

No worries, I don't quite know how it works but I believe it might be due to not assuming a global node installation.

Ah that would make sense if so. Ideally these shouldn't be globally installed either -- or any of the build deps for that matter -- but we've still got a fair bit of changes necessary before we can get there.