Code A Node Module – Part #1

This is a six articles series for building and publishing a node module from scratch. You can find all these articles below:

• Code A Node Module – Part #1
• Node Module Testing – Part #2
• Refactoring a Node Module – Part #3
• Node Module Testing – Part #4
• Node Module Naming – Part #5
• Publish a Node Module – Part #6

If you are new to JavaScript then it can be a bit hard to write your first node module. You are in luck. I have published several of them. In this piece, I am going to walk you through how you can build one from scratch.

Let's do it in steps to make things simpler.

#→ STEP #1

The first thing is creating a new repository. Head over to repo.new and create a repo with your node module name. For the sake of this article, I am going to create a repo with cli-alerts name.

Once you are done, clone this repo by running the following command inside your terminal.

git clone $your_repo_url

Now open this repository in your code editor. I am going to use VSCode.

#→ STEP #2

Quickly initialize npm inside of this repository. For that, you can either create a package.json file and fill it with key/value pairs or you can run the following command in the terminal.

npm init

Now answer the questions and when you are done, a package.json file will be created in your project.

#→ STEP #3

For this cli-alerts package, I will need a couple of node modules. These will be the dependencies of my node module. I am going to run the following command in my terminal to install all of them in a single go.

npm install chalk log-symbols

#→ STEP #4

I am going to create an index.js and a test.js file now. In my index.js file, I am going to write the following piece of code.

/**
 * CLI Alerts
 *
 * Cross Platform CLI Alerts with colors
 * Works on macOS, Linux, Windows.
 * Alerts: `success`, `info`, `warning`, `error`.
 *
 * @author Awais <https://twitter.com/MrAhmadAwais/>
 */
const chalk = require('chalk');
const sym = require('log-symbols');
module.exports = () => {
    console.log(`WORKING`);
};

I have to write some code in the test.js now to test whether my node module is working or not. For that, I am going to open my test.js file and write the following code inside it.

const alert = require('./index');
alert({
    type: `success`,
    msg: `All done!`
})

Now add the following key/value inside the package.json file so you can run test.js with npm test.

{
    "scripts": {
            "test": "node test.js"
    }
}

Open your terminal and run npm test. It will display WORKING on your terminal.

#→ STEP #5

Let's write some code now for our node module. If you take a look at the code in test.js, you would see that I am sending in an object in the alert function. Let's handle this object in our index.js file.

/**
 * CLI Alerts
 *
 * Cross Platform CLI Alerts with colors
 * Works on macOS, Linux, Windows.
 * Alerts: `success`, `info`, `warning`, `error`.
 *
 * @author Awais <https://twitter.com/MrAhmadAwais/>
 */
const chalk = require('chalk');
const sym = require('log-symbols');
module.exports = options => {
    const defaultOptions = {
        type: `error`,
        msg: `You forgot to define all options.`,
    };
    const opts = { ...defaultOptions, ...options };
};

I am handling an edge case in this code. In case user forgets to provide options, my default options will be used.

I am also using the spread operator to overwrite the key/value pairs of my default options if the user is providing the object. Then I am storing it in an another variable called opts.

#→ STEP #6

Now it's time to display a message on the console depending upon the options object. For that, I have added the following piece of code in my index.js file.

/**
 * CLI Alerts
 *
 * Cross Platform CLI Alerts with colors
 * Works on macOS, Linux, Windows.
 * Alerts: `success`, `info`, `warning`, `error`.
 *
 * @author Awais <https://twitter.com/MrAhmadAwais/>
 */
const chalk = require('chalk');
const sym = require('log-symbols');
module.exports = options => {
    const defaultOptions = {
        type: `error`,
        msg: `You forgot to define all options.`,
    };
    const opts = { ...defaultOptions, ...options };
    const { type, msg } = opts;
    if (type === `success`) {
        console.log(`${sym.success} ${chalk.green(msg)}`);
    }
    if (type === `error`) {
        console.log(`${sym.error} ${chalk.red.bold(msg)}`);
    }
};

I am using object destructuring to extract the type and message from the opts object. Then I am using the conditional statements log a proper message according to the type.

#Wrapping Up

So this is a simple piece of code that I have written for my cli-alerts node module. There is still a lot to do which I am going to take care in the next piece.