NodeJS require a global module/package

As per documentation, Node.js will search in the following locations by default:

1. Path specified in the NODE_PATH environment variable.

   ^{Note: NODE_PATH environment variable is set to a colon-delimited list of absolute paths.}

2. Current node_modules folder. (local)

3. $HOME/.node_modules (global)

   ^{Note: $HOME is the user's home directory.}

4. $HOME/.node_libraries (global)

5. $PREFIX/lib/node (global)

   ^{Note: $PREFIX is Node.js's configured node_prefix.}

   To check the current value of node_prefix, run:

   node -p process.config.variables.node_prefix
   

   ^{Note: Prefix corresponds to --prefix param during build and it's relative to process.execPath. Not to confuse with value from the npm config get prefix command.source}

If the given module can't be found, that means it is not present in one of the above locations.

Location of global root folder where modules are installed can be printed by: npm root -g (by default the path is computed at run-time unless overridden in npmrc file).

Solution

You can try the following workarounds:

• Specify your global module location in NODE_PATH environment variable. E.g.

  echo 'require("forever")' | NODE_PATH="$(npm root -g):$NODE_PATH" node
  

  To test and print the value of NODE_PATH, run:

  echo 'console.log(process.env.NODE_PATH); require("forever")' | NODE_PATH="$(npm root -g):$NODE_PATH" node 
  

• For more permanent solution, link your $HOME/.node_modules global user folder to point to the root folder, by running this command:

  ln -vs "$(npm root -g)" "$HOME"/.node_modules
  

  Then re-test it via: echo 'require("forever")' | node command.

• Temporary change the current folder to where the extension has been installed globally, before invoking the script. E.g.

  npm install -g forever
  cd "$(npm root -g)"
  echo 'require("forever")' | node
  cd -
  

• Configure global installation destination in npm userconfig file (see: npm help 5 npmrc) or by userconfig param (--prefix).

  To display the current config, run: npm config list.

  To edit the current config, run: npm config edit.

• Specify the full path of node modules location when calling require(). E.g.

  require("/path/to/sub/module")
  

• Install the package to custom location, e.g.

  npm install forever -g --prefix "$HOME"/.node_modules
  

  However, the installation will go under ~/.node_modules/lib/node_modules/, so the location still needs to be added.

  See: npm local install package to custom location

• Create a symlink in the current folder from the location of the global package. E.g.

  npm link forever
  

Apologies for the necromancy but I'm able to specify hard-coded paths to globally installed modules:

var pg = require("/usr/local/lib/node_modules/pg");

This isn't perfect but considering that Unity3d tries to "compile" all javascript that is included in the project directory I really can't install any packages.

In Node.js, require doesn't look in the folder where global modules are installed.

You can fix this by setting the NODE_PATH environment variable. In Linux this will be:

export NODE_PATH=/usr/lib/node_modules

^{Note: This depend on where your global modules are actually installed.}

See: Loading from the global folders.

After you install package globally you have to link the local project with global package

npm install express -g
cd ~/mynodeproject/
npm link express  

See here