NPM

In the previous chapter we learned how to make our code more reusable by splitting it up into modules. But it doesn't stop there. Now, we want to be able to share modules with other developers.

To make something like that possible, we would need a couple of things:

• a way to gather all those packages
• a way to search them, get information about it
• a way to implement, use them in our project

You saw it coming, didn't ya? Off course there is something like that, it is called npm or Node Package Manager

We call the modules who are available on npm "packages". Often, they exist of multiple modules, and they can make use of other packages on their own.

Registry

You can compare the registry with a large database (in fact, it is) that keeps track of all the packages, their versions etc.

Everyone (including you) can publish a package to this registry.

Website

To have easy access to all those packages, one can use the npmjs site.

Let's say we need a short, random string to create the url for a new chatroom. Do a search on unique string id and you get a couple of results. Picking the right one can be tricky, have a look at the description, the time it was last updated is also a good parameter.

Take a look at nanoid You get some kind of overview, often you will find a readme here with instructions how to install and use the package.

Notice the Repository link in the right column. Often the repositories of these packages are open source (but they don't have to be) This comes in handy when you stumble upon an issue, and you need some help. In this case, the full readme is on the GitHub repository

CLI

To interact (installing, updating and even publishing) with these packages, we use a command line tool npm

Node.js

You might have noticed the 'Node' in Node package manager, it won't come as a surprise that we need to install Node.js. Node.js is a JavaScript runtime to execute JavaScript on a server (i.e. not in a browser) This runtime is under continues development, so version updates arrive regularly. New versions mean new possibilities, but that implies that older packages aren't updated yet to newer Node.js versions. If we would just install a Node.js version system-wide, this would be problematic if we were working on two different project who require different Node.js versions.

nvm

Warning

Be sure to have a .zshrc file in your home directory. If you don't have one, create it with touch ~/.zshrc Otherwise, the installation of nvm will fail.

To handle different Node.js versions easaly, there is a tool called nvm (node version manager) Lets start by installing this one first. ¹ See the documentation for the most recent version, the command is something like this (but change the version number): curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.XX.X/install.sh | bash

To doule-check if everything went well, close every terminal instance and open a new window. Type nvm and you should get an overview with all the commands nvm has to offer.

Now the Node Version Manager is installed, but we still have to install a Node.js runtime. With the install command, we can install specific Node.js versions, but by using the alias node we simply install the latest stable version.

nvm install node

Have a look at the documentation to see which other options are possible.

¹ Assuming that the xcode command line tools are installed (run xcode-select –install otherwise)

npm

There is no need to install npm on its own, it comes with the installation of Node.js. Try it, just run npm on the command line.