This is a continuation of the Creating A CLI App. At that point I stopped at only implementing functionality to get either a specific comic or the latest one. I wanted to able able to also allow a user to be able to view a previous and next comic based on the current comic they are are viewing. Additionally, an added feature would be to get a random comic ranging from the initial comic to the most current one (1924 at the time of this post).

It seemed like it would be easy to implement (and it proved to be), but at that point I realized all those new options (random, next, and previous) were stringent on the current comic number being somehow referenced. As the most current number is updated 3 times a week, I had to find a way to be able to save it, store it, and update it quite easily. I thought about using an environment variable, however that would mean creating environment variables for users, which I did not want to do. Another approach would be using a database like postgreSQL, but I don’t believe that database is OS agnostic.

Today, while I was just perusing npmjs, I came across the perfect package: data-store. It was exactly what I needed! It was so easy to add the new functionality – just like I believed it would be.

IMPLEMENT PREVIOUS, NEXT, AND RANDOM

  1. Require data-store package: npm i data-store -S

    const store = require(‘data-store’)

  2. Add the new options in:

    program
  .version('0.1.0')
  .option('-c, --current', 'most current comic')
  .option('-p, --previous', 'previous comic from current')
  .option('-n, --next', 'next comic from current')
  .option('-s, --specific <value>', 'specific comic')
  .option('-r, --random', 'random comic')
  .parse(process.argv)

  3. In fetchComic function, get the num value from json. Use the num value to set the next and previous keys in the data store.

    async function fetchComic(url) {
  const response = await fetc(url)
  const data = await response.json()
  const { num, alt, img, title } = data

  store
    .set('current', num)
    .set('previous', num - 1)
    .set('next', num + 1)
}

  4. Add the cases for the new options:

    switch(process.argv[2]) {
...

case '-p': {
    return fetchComic(`https://xkcd.com/${store.get('previous')}/info.0.json`)
}

case '-n': {
    return fetchComic(`https://xkcd.com/${store.get('next')}/info.0.json`)
}

...
}

  5. As for the random comic feature, we could use a basic Math.random(), however we don’t want it to be just random, but also unique. Thankfully there’s a package for that: unique-random. This package ensures that you don’t get the same random comic twice in a row.

    npm i unique-random -S

    const rand = require(‘unique-random’)

Add the random option in your switch statement:

```js
 ...

 case '-r': {
   return fetchComic(`https://xkcd.com/${rand(1, store.get('current'))}/info.0.json`)
 }
 ...

```

NEXT STEPS

Prezto! We have the core functionalities completed, although there’s no testing included. Ideally we would start testing and work backwards to get the core features, but I am trying to find a new test runner and/or framework to experiment with, other than just being content with mocha and chai. Hopefully, by the end of the week, I will have made my decision and added some units tests in. As for now, I added a git tag on it (v0.1.0) and published it on npm as xkcli.