Nodejs - Cant import module unless use the full path

I installed it and am trying to use the w3 module (on windows).

I have altered my global repo location to: C:\Users\<user>\.node_modules_global and installed the web3 module with the command bellow, which created a new folder on the node_modules_global folder:

npm install ethereum/web3.js --global

When I try to run:

Web3 = require('web3') it, I get an

Error: Cannot find module 'web3'

however, if I use the fullpath:

Web3 = require('C:\\Users\\<user>\\.node_modules_global\\node_modules\\web3')

It works.

Any idea what could be causing this issue? (I have added C:\\Users\\<user>\\.node_modules_global to the SYSTEM PATH).

Solution

Your installing it globally, so it is saved to your user folder, rather than in the project, and node is configured by default to look in node_modules.

Two options to fix this:

(a) Save Packages Locally Instead
- Use just npm install ethereum/web3.js or npm install ethereum/web3.js --save to install it to the node_modules directory within your project. (You must have cd'd into your project folder first!)
(b) Make Node look in your global folders by default
- use "NODE_PATH": "C:\\Users\\<user>\\.node_modules_global\\node_modules"

How to install locally, and how to install globally

To locally install a module, just do npm install my-module, or if you'd also like to add it to your package.json, then do npm install my-module --save
To Globally install a module, use npm install my-module --global

When to use local and global modules

You should:

Install a module locally if you're going to require() it.
Install a module globally if you're going to run it on the command line.

Source: https://nodejs.org/en/blog/npm/npm-1-0-global-vs-local-installation/

Changing Node path

You can set the NODE_PATH environment variable to your own value, and your application will by default look there, instead of the projects node_modules directory.

See here: http://nodejs.org/api/modules.html#modules_loading_from_the_global_folders