Building a Node JS interactive CLI

“A robot named Pepper holding an iPad” by Alex Knight on Unsplash

NodeJS can be very useful when it comes to building Command-line Interfaces also known as CLI’s.

In this post, I’ll teach you how to build a CLI that asks some questions and creates a file, based on the answers.

The final result

Getting started

Let’s start by creating a brand new npm package

mkdir my-script
cd my-script
npm init

NPM will ask some questions. After that, we need to install some packages.

npm install --save chalk figlet inquirer shelljs

What these packages do:

• chalk — Terminal string styling done right
• figlet — Figlet is a program for making large letters out of ordinary text
• inquirer — A collection of common interactive command line user interfaces
• shelljs — Portable Unix shell commands for Node.js

index.js file

Now create a index.js file with the following content:

Planning the CLI

it’s always good to plan what a CLI needs to do before writing any code.

This CLI will do just one thing: Create a file.

It should ask a couple of questions and after that, show a success message with the created file path.

The questions are: what is the filename and what is the extension.

The first function is the script introduction. Let’s use chalk and figlet to get the job done.

Now it’s time to write a function that asks questions.

Notice the constants FILENAME and EXTENSIONS that came from inquirer.

The next step is to create the file.

And last but not least, show the success message along with the file path.

Let’s test the script by running node index.js.

Yay! It works!

And here is the final code:

Using the script anywhere

To execute this script anywhere add a bin section in your package.json file and run npm link

After running npm link this script will be available anywhere.

That’s what happens when you run this command:

/usr/bin/creator -> /usr/lib/node_modules/creator/index.js
/usr/lib/node_modules/creator -> /home/hugo/code/creator

It links the index.js file as an executable.

This is only possible because of the first line of the script: #!/usr/bin/env node

Now you can run this script by just calling:

$ creator

Hope it helps :)

Keep reading:

Extracting a React JS component and publishing it on NPM

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