NodeJS require a global module/package

Question

I'm trying to install globally and then use forever and forever-monitor like this:

npm install -g forever forever-monitor

I see the usual output and also the operations that copy the files to the global path, but then if I try to require("forever"); I get an error saying that the module wasn't found.

I'm using latest version of both node and npm and I already know about the change that npm made in global vs local install, but I really don't want to install localy on every project and I'm working on a platform that doesn't support link so npm link after a global install isn't possible for me.

My question is: why I can't require a globally installed package? Is that a feature or a bug? Or am I doing something wrong?

PS: Just to make it crystal clear: I don't want to install locally.

Solution 1

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.

Solution 2

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

Solution 3

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.

Solution 4

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
  

Solution 5

I know this is an old question, but I ran into this when trying to do some version checking using semver in a preinstall script in package.json. Since I knew I can't depend on any local modules installed, I used this to require semver from the global node_modules folder (as npm depends on it I know it's there):

function requireGlobal(packageName) {
  var childProcess = require('child_process');
  var path = require('path');
  var fs = require('fs');

  var globalNodeModules = childProcess.execSync('npm root -g').toString().trim();
  var packageDir = path.join(globalNodeModules, packageName);
  if (!fs.existsSync(packageDir))
    packageDir = path.join(globalNodeModules, 'npm/node_modules', packageName); //find package required by old npm

  if (!fs.existsSync(packageDir))
    throw new Error('Cannot find global module \'' + packageName + '\'');

  var packageMeta = JSON.parse(fs.readFileSync(path.join(packageDir, 'package.json')).toString());
  var main = path.join(packageDir, packageMeta.main);

  return require(main);
}

I like this approach because this doesn't require the install of any special modules in order to use.

I didn't go with a NODE_PATH solution like others have suggested since I wanted to get this to work on anyone's machine, without having to require additional configuration/setup before running npm install for my project.

The way this is coded, it is only guaranteed to find top-level modules (installed using npm install -g ...) or modules required by npm (listed as dependencies here: https://github.com/npm/npm/blob/master/package.json). If you are using a newer version of NPM, it may find dependencies of other globally installed packages since there is a flatter structure for node_modules folders now.

Hope this is useful to someone.

View more solutions

Comments

[Marecky]

I just leave it here github.com/yarnpkg/yarn/issues/2049 github.com/yarnpkg/yarn/issues/2049#issuecomment-337870443

[Skippy le Grand Gourou]

Possible duplicate of How do I import global modules in Node? I get "Error: Cannot find module <module>"?

[localhostdotdev]

so it's ~/.config/yarn/global for yarn

[alexandernst]

I'm running on a platform that doesn't support link (as my question states) blog.nodejs.org/2011/04/06/npm-1-0-link

[user568109]

which platform are you using ?

[alexandernst]

I'm on Windows XP. I'm de deploying to a Linux machine (which does support link). Anyways, I'd like to be able to require modules on my dev machine (the XP one)

[user568109]

can u try fsutil for symlink it looks like some work but worth trying serverfault.com/questions/7109/…

[alexandernst]

I really don't want to mess with link (nor symbolic links at all). I just want to install packages globally and require them. I know NPM was re-designed to avoid this, but how hard could it be to achieve something like this?

[Drew Noakes]

On my Ubuntu 13.10 machine, the global path for modules is different than you show here. I had to use export NODE_PATH=/usr/local/lib/node_modules instead.

[Wes Johnson]

If you're on Windows 7 / 8 and haven't overridden any of Node's install defaults, setting the NODE_PATH environment variable to C:\Users\{USERNAME}\AppData\Roaming\npm\node_modules will likely work.

[AnnanFay]

What if I don't have a project? Say ~/some-stand-alone-random-nodejs-test.js. I don't want to turn my home folder into a project directory. I don't want to create new folders for every small experiment.

[dynamiclynk]

Worked perfect on Windows 8.1. From node command line cd to my projects' local node_modules folder then executed npm link <module> Then you will see a shortcut(link) created in your projects' node_module folder referencing the global node module.

[theblang]

@WesJohnson Just %AppData%\npm\node_modules will work on Windows 10.

[Flion]

watch out, if you ever remove the project, including the node_modules folder, you'll remove your global module installation

[Paulo Oliveira]

If I set NODE_PATH can I use global and local modules simultaneously?

[Alexander Mills]

interesting, but the NODE_PATH method is probably more canonical

[amenthes]

the beauty of NODE_PATH is also, that you don't need to change any code. (my use case is grading a lot of student projects, where I don't want to run npm install for each one, and also don't want them to provide node_modules directory).

[lifeisfoo]

@DrewNoakes same path in alpine linux

[Slipp D. Thompson]

Unity3D doesn't support JavaScript. It supports a JS-like syntax for its Boo interpreter/compiler (Boo is a Python-like language for .NET) that is deceptively marketed as “JavaScript”. The more-accurate name for the language Unity supports is UnityScript. Because it's not even close to the same language, next to none of the JS written for the web or for Node.js will work in Unity. Much more info on the differences on the official Unity wiki: wiki.unity3d.com/index.php/UnityScript_versus_JavaScript

[Carmela]

This is not working for me. I've set the NODE_PATH to the exact location of globally installed node_modules but simple require('module_name') still doesn't work. (using linux)

[jpaugh]

@flion That varies greatly depending on which OS and which method you use to remove the files. Every OS which uses symlinks (or shortcuts) provides a method to remove the link without removing the target; but yes, you do need to be careful.

[Király István]

@Carmela, you must export NODE_PATH in the shell process where you actually start node.

[Király István]

It looks like 4. Current node_modules folder. (local) takes priority over 3. $PREFIX/lib/node (global)

[Király István]

Local node_modules folders always take priority over global folders!

[holmberd]

Alternatively instead of a static path, i.e. if you are using NVM: NODE_PATH=$(npm root -g)

[thisismydesign]

No, it will not do the trick because you can't require requireg in the first place, this is the whole point.

[Luis Paulo]

No. This is the generic way of getting the global node_modules. This is an old answer but I remember I got it from somwhere in the documentation. Anyway, in my computer (in 2020) the global npm node_modules directory is usr/lib/node_modules. Anyway, I trust npm config get prefix because it is used globally by npm whenever a global package is installed so it should be right.

[Luis Paulo]

Either way (I didn't say this in my initial answer because I wasn't very experienced in Node.JS), using globally installed packages in a program is an edge use case and should seldom be done because in a project it will create problems whenever the project is committed to VCS and cloned in another environment due to that specific dependency not being in the package.json file or in yarn.lock/package-lock.json.

[Luis Paulo]

Oh! I understand now. I believe you're mistaking the NODE_PATH with PATH. PATH is where a shell will look for executables. NODE_PATH is where node will look for packages. It will start by looking at the current directory for a node_modules folder, then it's parent, then it's parent, ... until it finds a node_modules folder which contains that module. However, if you install a package globally, it won't be inside any node_modules folder above the script's current directory so you use NODE_PATH as a fallback where node will look for packages.

[Ryan Taylor]

ahahahah @Luis Paulo you're totally right!! I'm sorry! I'll try and delete some of my comments to prevent confusion, nice job and thank you

[Luis Paulo]

@Ryan Taylor You shouldn't delete comments and questions once they get resolved because someone else could have the same ones. Now it just looks like I had a monologue in the comments! ahahahah

[Vlad]

or for custom global path var pg = require('/home/<username>/.npm-global/lib/node_modules/pg')

[ruffin]

Never apologize for necromancy. It's a badge for cryin' out loud. ;^)

[Leo Gasparrini]

Thanks man! I appreciate it, it's working fine now. JIC I want to mention that I could fix it on macOS

[Henrique Bruno]

export NODE_PATH=$(npm root -g) also works for n

[Kenneth Garza]

i was having issues with shellJs + typescript + ncc + docker working properly. This answer lead me down the right path and finally got it to work using a globally installed shelljs and requireq. let shell = require("requireg")("shelljs");

[José Manuel Blasco]

Awesome function! Thank you!

[Jeff]

@holmberd definitely the preferred answer! Do you happen to know if there's a hook in nvm so that it will automatically be re-exported following nvm use?

[holmberd]

@Jeff not that I know off. You can always create an alias for nvm use to also exec source.