Does node still use node_prefix as a place to search for modules?

[myrne]

Latest node documentation says:

Loading from the global folders

If the NODE_PATH environment variable is set to a colon-delimited list of absolute paths, then node will search those paths for modules if they are not found elsewhere. (Note: On Windows, NODE_PATH is delimited by semicolons instead of colons.)

Additionally, node will search in the following locations:

1: $HOME/.node_modules
2: $HOME/.node_libraries
3: $PREFIX/lib/node
Where $HOME is the user's home directory, and $PREFIX is node's configured node_prefix.

Does this bit about $PREFIX this still hold true? I can't find a reference to it in the code.

In lib/modules.js, it says

Module._initPaths = function() {
  var isWindows = process.platform === 'win32';

  if (isWindows) {
    var homeDir = process.env.USERPROFILE;
  } else {
    var homeDir = process.env.HOME;
  }

  var paths = [path.resolve(process.execPath, '..', '..', 'lib', 'node')];

  if (homeDir) {
    paths.unshift(path.resolve(homeDir, '.node_libraries'));
    paths.unshift(path.resolve(homeDir, '.node_modules'));
  }

  if (process.env['NODE_PATH']) {
    var splitter = isWindows ? ';' : ':';
    paths = process.env['NODE_PATH'].split(splitter).concat(paths);
  }

  modulePaths = paths;

  // clone as a read-only copy, for introspection.
  Module.globalPaths = modulePaths.slice(0);
};

Maybe the refrence to node_prefix been replaced by this expression? path.resolve(process.execPath, '..', '..', 'lib', 'node');

Also

> process.config.variables.node_prefix
'out/dist-osx/usr/local'

This directory which does not exist. Maybe this variable is not used at runtime anymore? Or should I read this as a relative path (no / after all), which gets added to something else? If so, what?

Either way, the documentation doesn't make sense to me on this point.

[bnoordhuis]

The module system looks for modules relative to the path of the node binary, which happens to be $PREFIX/lib/node because the binary itself is always installed in $PREFIX/bin. And yes, it's this line of code.

Note that @isaacs (module.js and npm maintainer) considers it deprecated (in the sense that you shouldn't use it, not that it will be removed in the future) and I tend to agree with him on this.

The process.config variable is generated from the config.gypi file that is created when you run configure. The node_prefix field is mainly for use by the installer. process.config itself is there for the benefit of module authors. node-gyp also uses it.

[myrne]

Thanks for explaining!

[coolaj86]

It would appear that NODE_PATH has, in fact, resurfaced as the supported and proper way to do this?

• https://nodejs.org/api/modules.html

And that NPM_CONFIG_PREFIX is the companion variable that should also be set?

• https://docs.npmjs.com/misc/config

So if I were packaging and installing an app with a specific version of node and set of modules I would want to set both like this?

NODE_PATH=/opt/my-app/lib/node_modules:/some/other/node_modules
NPM_CONFIG_PREFIX=/opt/my-app