Problem: inconsistent formatting in js files

[porcellus]

#225 is inactive and enforcing strict linting/formatting rules on PRs conflict with C4, but I still think the project would benefit from a consistent code style. I propose periodically cleaning our codebase, this way we don't block PRs and still get the benefits.
Using prettier to do the formatting would make it very simple to have a consistent look. (it mainly reformats whitespaces)