NPM, Modules and Dependencies


  • npm install <module> --save - install a module and save it as a dependency in package.json
  • npm install <module> --dev - install a module and save it as a devDependency in package.json
  • npm install <module> -g install a module globally
  • npm update <module> updates a module to latest version
  • npm init - create a package.json
  • npm install - install all dependencies listed in package.json

Node Package Manager, installing and managing dependencies.

install a module

npm install lodash
npm install async request express

-g = install globally --save = also save it as a dependecy in the package.json file.


It installs the modules in the node_modules folder in your project directory. If you are using Git, you don’t need to commit this folder, you just need to inslude the package.json file and the user will be able to install all dependencies on their own computer.

including a module in your project

install it with npm install and then in your code, do:

var async = require("async");
var _ = require("lodash");

What we did is use require() to include the module and saved it as a variable. Now we can call all related functions on the async keyword.


package.json file keeps track of all your modules, their version and basic project details. The easiest way to create one is using

npm init

entry point is usually the index file of your project. Node looks into your package.json file to figure out what file it should load.

Even if you init a file after you have already installed some modules, it’ll include all existing modules.

You need a package.json in order to use --save. Just a simple file with curly brackets should work.



  • follows Semantic Versioning (semver) for specifying version ranges
  • The tilde ~ matches the most recent minor version (middle number). It means approximately equivalent to version version
  • The caret ^ matches the most recent major version (first number). It means compatible with version read more
  • install –-save prepends a caret ^ instead of a tilde ~

There are about a dozen more ways of specifying versions, including but not limited to version, *, 1.2.x, >, <, >=, >=, http://.., path/path/path, range || range etc.

read more

In the simplest terms, the ~ matches the most recent minor version (the middle number). ~1.2.3 will match all 1.2.x versions but will miss 1.3.0.

The ^, on the other hand, is more relaxed. It will update you to the most recent major version (the first number). ^1.2.3will match any 1.x.x release including 1.3.0, but will hold off on 2.0.0.

install dependencies

If you have an existing package.json file, you can run:

npm install

to install all the dependencies mentioned in that file

installing globally

When you need project to run things on the command line and not just in your project, for example grunt or gulp, you install them globally with the -g flag

npm install grunt -g

The global installs are for the command line tools. But if you also require it in your project, you need to install it locally in your project as well.

finding modules

Do a search on