npm (Node Package Manager) is on online repository used by Node.js developers. It contains multitudes of libraries of pre-packaged code that are used by millions of people across various applications. Much of it is free and open-source.
Usually you will use an npm package for something that is not unique to your app, meaning – there’s no need to reinvent the wheel. These could include things like email validation, a UI library like React or a debugging tool.
You can install both local and global dependencies:
Local packages are installed directly on your app in the node modules directory and are listed in the package.json file. They can be installed on your project with a simple npm install command. In order to make use of a local package in a particular code file, you will need to include require(‘package-name’).
When you install a package globally you don’t install it directly into your source files, but rather in a single place on your system so that it can be re-used across various applications. This can be done with an npm install -g command. Globally installed packages give access to a new command in the terminal and should really only be used for packages that you intend to utilize across a number of projects. For instance, the nodemon package will allow you to automatically restart your app whenever the code is updated. This is potentially helpful across a whole range of apps.
Do you have any favorite npm packages?
Ciara Anderson, PhD 