[Node.js] Setup a Node.js CLI

Creating a CLI in Node.js just takes a extra step or two because they are really just an ordinary Node.js app wrapped behind a bin command. For this exercise, we'll create a CLI that opens a random reddit post in our browser. To start, we'll create a new folder and make it a package with npm init.

Once inside that folder, create a file reddit.mjs:

// reddit.mjs
#! /usr/bin/env node

console.log('hello from your CLI')

The fist line on that file is called a shabang or hashbang. It's needed to tell the machine where the interpreter is located that is needed to execute this file. For us, that will be Node.js.

Next we need to tell Node.js what the name of our CLI is so when can actually use it in our terminal. Just have to add a section to our package.json:

"bin": {
  "reddit": "./reddit.mjs"
}

Once installed, this package will have it's bin command installed into your machine's bin folder allowing us to use the reddit command.

Lastly, we must install our own package locally so we can test out the CLI. We could just execute the file with the node runtime, but we want to see the CLI actually work.

npm install -g

We can simply instll with no args which tells npm to install the current director. The -g flag means we want to globally install this package vs in a local node_modules.

You should now be able to run reddit and see your log print.