Added tests & normal function convertion

[Croustys]

Welcome to JavaScript community

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new JavaScript files are placed inside an existing directory.
• All filenames should use the UpperCamelCase (PascalCase) style. There should be no spaces in filenames.
  Example:UserProfile.js is allowed but userprofile.js,Userprofile.js,user-Profile.js,userProfile.js are not
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

[ruppysuppy]

I wasn't very clear about the arrow function part. I meant don't use a one liner as the aim of the repository is to help beginners. Break the ternary operation into

if (n === 0){
    return 1
}
return n * factorial(n - 1)

Rename the function as factorial.
Add comments about the algorithm/operation
Add tests (see example)

And from next time modify the branch you created and don't create a new pull request

[Croustys]

On last PR you required a change, which made me unable to edit those files and for some reason couldnt commit new changes to the PR either.

Regarding the one liner solution, you could’ve edited my PR with the solution you like, since you just typed it out in your last comment. About adding comments for beginners, probably easier for them to just google the problem and let other websites explain the code’s behaviour rather than reading comments randomly across the code trying to explain which line does what.

Also since this should be a beginner friendly code as you mentioned, im not entirely sure why tests are necessary.

Thanks 😌