automate code formatting

[boneskull]

I've played with prettier a bit, and it seems like a reasonable solution (especially when combined with husky) to enforce a code style across the codebase.

This should prevent nitpicks about style in PRs.

We could also likely make the pre-commit hook run eslint --fix.

semver-patch because it should have no impact upon API or program output.

[boneskull]

A thing that will happen if we do this is pretty much every file will be touched, because there's no way to disable some of the disagreements between prettier and semistandard.

[boneskull]

to be more specific, prettier will remove the spaces after the function keyword and that's that. I don't really care. does anyone care?

fwiw, I'm cool with using a more unopinionated formatter if one exists. the killer feature here for Mocha is automatic application of a style--not the style itself--but prettier conflates the two. that's fine for FB and solves their problem, but it's not necessarily Mocha's problem.

[boneskull]

(because Mocha is not thousands of javascript projects, it's just one)

[ScottFreeCode]

I wouldn't at all mind losing the spaced between function and (. I've never seen that outside of JS projects that rely on Standard for their linting.

I believe XO is designed to work better with Prettier and to be less stubbornly opinionated, if I heard correctly in the past.

[bakkot]

Drive-by: it looks this issue was addressed by #3344?

[boneskull]

@bakkot totally missed it, thanks.