Install a package
SYNOPSIS
npm install (with no args in a package dir)
npm install <tarball file>
npm install <tarball url>
npm install <folder>
npm install <name> [–save|–save-dev|–save-optional]
npm install <name>@<tag>
npm install <name>@<version>
npm install <name>@<version range>
npm i (with any of the previous argument usage)
This command installs a package, and any packages that it depends on. If the package has a shrinkwrap file, the installation of dependencies will be driven by that. See npm-shrinkwrap(1).
A package is:
a) a folder containing a program described by a package.json file
b) a gzipped tarball containing (a)
c) a url that resolves to (b)
d) a <name>@<version> that is published on the registry with (c)
e) a <name>@<tag> that points to (d)
f) a <name> that has a “latest” tag satisfying (e)
g) a <git remote url> that resolves to (b)
Even if you never publish your package, you can still get a lot of benefits of using npm if you just want to write a node program (a), and perhaps if you also want to be able to easily install it elsewhere after packing it up into a tarball (b).
More info …
https://npmjs.org/doc/install.html