Last week, I wrote an article about building a Node.js CLI using yargs. I introduced it saying we use cli tools everyday to simplify common tasks in our jobs. I made myself a couple of cli like gitmoji-changelog. It is a changelog generator for gitmoji commit convention.

I would like to share with you a few libraries I used on this project and while contributing to Gatsby. Gatsby is a good source of inspiration, consider contributing to it. I learned a lot while doing it (they give free swag to thank contributions 🤫).

yargs

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It is a library that helps you defining your tool's interface. It also parses arguments for you. The icing on the cake is that yargs generates automatically an help menu.

Here is a simple example that displays a message "Hello [something]" a certain amount of times.

require('yargs')
  .command('$0 [name]', 'say hello', (yargs) => {
    yargs
      .positional('name', {
        describe: 'hello\'s target',
        default: 'world'
      })
      .option('times', {
        alias: 't',
        type: 'number',
        default: 1,
        description: 'number of times to say hello'
      })
  }, (argv) => {
    for (let i = 0;i < argv.times; i++) {
      console.log(`Hello ${argv.name}!`)
    }
  })
  .argv

Result:

prompts

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A common use case in cli tools is asking user for information. Prompts is a lightweight library based on promises. It implements an exhautive list of question's types.

(async () => {
  const prompts = require('prompts')

  const response = await prompts({
    type: 'confirm',
    name: 'value',
    message: 'Can you confirm?',
    initial: true
  })

  console.log('Reponse: ', response.value)
})()

Result:

signale

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Standard console API provides only a few methods to display information. Signale comes with 19 built-in methods (logs are prefixed with emojies ❤️)! You can also implements custom loggers.

const signale = require('signale')

signale.success('CLI started');

const options = {
  types: {
    santa: {
      badge: '👽',
      color: 'magenta',
      label: 'alien',
      logLevel: 'info'
    }
  }
}

const custom = new signale.Signale(options);

custom.santa('E.T go home')

signale.complete('Call sent')

Result:

chalk

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It is a pain in the neck to add style to a cli output. Chalk provides an easy-to-use API to colorize logs. It also supports template literals!

const chalk = require('chalk')

console.log(`${chalk.blue('Welcome')} in the activity monitor${chalk.red('!')}`)

console.log(chalk.green(`Your computer seems in ${chalk.underline('great')} shape.`))

console.log(`
envinfo:
CPU: ${chalk.red('90%')}
RAM: ${chalk.green('40%')}
DISK: ${chalk.yellow('70%')}
`)

Result:

progress

🔗 repository

Another common use case is dealing with asynchronous operations. It is nice to give user a percentage of completion when your cli is doing a heavy computation. Progress is an highly customizable ascii progress bar. It comes with a bunch of options and standard information (percentage, total, estimated completion, ...) to display on the progress bar. You can also add your own information.

const ProgressBar = require('progress')

let ticks = 0

const bar = new ProgressBar(
  'Rocket launch :bar in :counter',
  { total: 10, width: 50 },
)

const timer = setInterval(function () {
  ticks++
  bar.tick({ counter: 10 - ticks })
  if (bar.complete) {
    console.log('\n🚀')
    clearInterval(timer)
  }
}, 100)

Result:

configstore

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Earlier we saw Prompts to ask user information. It is also nice to store its answer to avoid asking it again and again. Configstore is a library that persists data for you. It stores it in a json file on the user's disk. It handles well the dot notation!

const Configstore = require('configstore')
const packageJson = require('../package.json')

const config = new Configstore(packageJson.name)

config.set('answer', true);
console.log('answer:', config.get('answer'));

config.set('a.really.deep.config', true);
console.log('a.really.deep.config:', config.get('a.really.deep.config'));

config.delete('answer');
console.log('answer:', config.get('answer'));

Result:

envinfo

🔗 repository

As frontend developer I use user-agent to get information about my user device. It helps a lot to reproduce bugs for example. As cli developer you don't have access to this kind of information. envinfo is a library that generates reports that users can provide when opening issues on your project.

(async () => {
  const envinfo = require('envinfo')

  const environment = await envinfo.run(
    {
      System: ['OS', 'Shell'],
      Binaries: ['Node', 'Yarn', 'npm'],
      Utilities: ['Git'],
    },
    { markdown: true }
  )

  console.log(environment)
})()

Result:

Alternatives exist for these libraries but I used these ones and I enjoy working with them. In my opinion, they covers the majority of problems you might encounter while coding cli tools.

Hope it will help 🙌 Happy cli coding!

Feedback is appreciated 🙏 Please tweet me if you have any questions @YvonnickFrin!