Move a module from devDependencies to dependencies in npm package.json

New Note: You probably don't want or need to do this. What you probably want to do is just put those types of command dependencies for build/test etc. in the devDependencies section of your package.json. Anytime you use something from scripts in package.json your devDependencies commands (in node_modules/.bin) act as if they are in your path.

For example:

npm i --save-dev mocha # Install test runner locally
npm i --save-dev babel # Install current babel locally

Then in package.json:

// devDependencies has mocha and babel now

"scripts": {
  "test": "mocha",
  "build": "babel -d lib src",
  "prepublish": "babel -d lib src"
}

Then at your command prompt you can run:

npm run build # finds babel
npm test # finds mocha

npm publish # will run babel first

New NEW Note: For awhile now we have had npx, which allows you to run the devDependencies commands without needing to add them to your scripts section (if you want). For example:

npx webpack

But if you really want to install globally, you can add a preinstall in the scripts section of the package.json:

"scripts": {
  "preinstall": "npm i -g themodule"
}

So actually my npm install executes npm install again .. which is weird but seems to work.

Note: you might have issues if you are using the most common setup for npm where global Node package installs required sudo. One option is to change your npm configuration so this isn't necessary:

npm config set prefix ~/npm, add $HOME/npm/bin to $PATH by appending export PATH=$HOME/npm/bin:$PATH to your ~/.bashrc.

Another, probably better option is to just use nvm to manage Node and you won't have that problem.

The npm install command will install the devDependencies along other dependencies when run inside a package directory, in a development environment (the default).

Use npm install --only=prod (or --only=production) to install only dependencies, and not devDependencies, regardless of the value of the NODE_ENV environment variable.

Source: npm docs

Note: you may also need --no-optional

Note: Before v3.3.0 of npm (2015-08-13), the option was called --production, i.e. npm install --production.