Format and lint

[SleeplessByte]

• enable eslint for all exercises
• format all files the same way
• fix a stub (simple-linked-list)

[tejasbubane]

@SleeplessByte This is so good! 💚

enable eslint for all exercises

Do we need the .prettierrc file? I am a little confused here because I don't see prettier anywhere in the codebase.

Will CI check for lint be added in separate PR?

[SleeplessByte]

I didn't yet decide if we wanted to add it by default, but first wanted to see your reaction hehehehe.

I'll add it to the maintainers workflow and I'll add the CI. We already have it for v3, so easy copy.

[SleeplessByte]

@tejasbubane

• It now checks formatting in CI
• It forces the same consistent version of prettier for formatting and checking it
• It adds npx babel-node scripts/format to run prettier
• It adds instructions in the docs about that new action
• It adds instructions in the docs about how to set-up your editor to "automatically" do it.

In reality, code formatted between version 2.x and 2.y is going to be very similar if not the same, so most of the time prettier will "just work" in editors. We just don't want to auto-install a version that has to be kept in sync with the repo unless that's necessary. We can later decide to add it as devDependency (but remove it in the exercises, like shelljs).

Bonus. On any future pr, add a comment with:

/format

and it will auto-format the code and commit it. No need to install/run anything.

EXAMPLE: #839 (comment)

[tejasbubane]

Amazing work @SleeplessByte 👍