Packages are libraries that are included in your program.
Local packages must be installed in every project using them. While a global package needs to be installed in only one location.
To install a package globally, issue npm install with
the -g or --global option.
You can process global packages by
adding the -g option to most npm commands.
To view the installed global packages use the command npm ls -g.
To locate the global node_modules folder use the npm root -g command.
All of the NPM commands we have seen take an optional -g flag to indicate that you are working with global modules.
The following code installs the browserify package globally.
npm install -g browserify
This put browserify on the command line, which we used in the previous chapter.
To update global packages
npm update -g package-name
To list global packages
npm ls -g
To uninstall packages
npm rm -g package-name
For example, to uninstall Browserify, you would run
npm rm -g browserify
When installing modules globally, NPM does not modify your system configuration.
The global modules are placed in a location where they become available on the command line.
Modules installed globally should not be used with a require function in our code, although many packages that support the global flag also support being installed locally in our project (the node_modules folder).
If installed locally, that is, without the -g flag, we can use them with the require function as we have already seen.
A good and simple example of this is the rimraf module (www.npmjs.org/package/rimraf).
If rimraf is installed globally (npm install -g rimraf),
it provides a command line utility that you can use
cross platform for recursively and forcefully removing a directory.
To remove a directory myData after installing rimraf globally, run
rimraf myData
To do the same from your Node.js code, install rimraf locally (npm install rimraf), create an app.js as shown.
var rimraf = require('rimraf');
rimraf('./foo', function (err) {
if (err)
console.log('Error occured:', err);
else
console.log('Directory foo deleted!');
})